INVESTIGATION INTO PRODUCTION AND REPRODUCTION SELECTION CRITERIA IN AFRINO SHEEP

M.A. Snyman

AIM AND OBJECTIVES

The aim of this project is to identify effective selection methods and criteria to increase efficiency of mutton and wool production under extensive grazing conditions.

The objectives of this study are:

·      To evaluate selection criteria to improve reproductive efficiency of dual purpose sheep breeds under extensive grazing conditions

·      To evaluate selection criteria to improve mutton and wool production efficiency of dual purpose sheep breeds

·      To maintain a comprehensive database for evaluation of selection criteria for mutton and woolled sheep in South Africa

·      To provide research animals for other projects, such as the parasite project (AP2/2) and the project on maternal values (AP2/7).

BACKGROUND

This is a co-operative project between the Northern Cape Department of Agriculture and Land Reform and Grootfontein Agricultural Development Institute (GADI). The project is continuing as in the past. Researchers and technicians from GADI are still responsible for data collection and capturing, linear scoring of subjective traits and selection of breeding sires and dams. This is done in collaboration with the farm personnel at Carnarvon Experimental Station. Lambs of the flock are also part of the projects on parasite resistance (AP2/2) and ultrasound scanning of Longissimus dorsi area (AP2/5). Ewes of the flock are part of the project on maternal values in sheep (AP2/7).

RESULTS AND DISCUSSION

Selection strategy

Selection in the flock is aimed at increasing reproductive performance, increasing body weight, decreasing fibre diameter, keeping wool weight constant and improving wool quality traits.

Productive performance

The average productive performance of the ram and ewe lambs over the past 15 years and production of 2004-born ram and ewe lambs, are summarised in Table 1. Productive performance of the ewe flock is presented in Table 2.

Table 1. Average productive performance (±SE) over the past 15 years, and production of 2004-born ram and ewe lambs in the Carnarvon Afrino flock

Table 2. Production of Afrino ewes over the past 15 years in the Carnarvon flock

Genetic trends

From the genetic trends it is evident that the selection objectives with regard to reproductive performance, body weight and fibre diameter have been obtained. A positive direct genetic trend was observed for birth weight, while a slightly negative maternal genetic trend was evident for birth weight, indicating a negative direct maternal genetic correlation. However, positive direct as well as maternal genetic trends were observed for 42-day body weight and weaning weight. Positive trends were also observed for the older body weights.

Too much emphasis on reducing fibre diameter, without considering wool weight, led to a slight reduction in clean fleece weight up to 2001. Furthermore, a reduction in the density of the fleece also occurred. The emphasis on crimp quality, together with the emphasis on fibre diameter, also led to a correlated increase in the appearance of creeping belly.  It was therefore decided in 2001 that less emphasis would in future be put on fibre diameter, especially with the selection of young ewes, and more emphasis on wool weight. As far as the other fleece traits are concerned, positive genetic trends were observed for staple length, evenness of fleece and staple strength.

CONCLUDING REMARKS

·      The project is running according to the project protocol and progress has been satisfactory. As this is a long-term project, which involves the evaluation of selection criteria, it will continue in its current form.

·      The data set collected on this research flock, is one of the most comprehensive data sets on productive and reproductive traits of woolled mutton sheep available worldwide.

·      Results of the project on maternal values could probably be implemented in the selection program in five or six years’ time.

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EVALUATION OF GENETIC FINE WOOL ANIMALS UNDER NATURAL CONDITIONS IN THE NON-TRADITIONAL FINE WOOL PRODUCING AREAS OF THE RSA

W.J. Olivier

AIM AND OBJECTIVES

The aim of this project is to evaluate genetic fine wool animals under natural grazing conditions in the non-traditional fine wool producing areas of the RSA.

The objectives of this study are:

·      To evaluate genetic fine wool animals in different environments

·      To compare the reproduction, growth and wool characteristics of genetic fine wool animals with that of strong wool animals in the non-traditional fine wool producing areas.

BACKGROUND

The worldwide tendency towards finer wool has lead to the establishment of a project in 1988 by the Department of Agriculture to improve the production of finer wool.  This project consisted of three phases, namely:

Phase 1: Establishment of a genetic fine wool flock

Phase 2: To improve and enlarge this flock

Phase 3: Evaluation of these fine wool animals under different environments.

Phase 1 was completed successfully in 1996 with the establishment of the fine wool flock at the Cradock Experimental Station. Phase 2 started in 1997 and was completed in 2003.

Phase 3 was initiated in 1990 with the establishment of the fine and strong wool Merino flocks at Grootfontein Agricultural Development Institute. Due to the fact that neither the farming conditions nor the grazing conditions at Grootfontein is representative of that of the RSA, a conclusion could not be made regarding the viability and sustainability of fine wool production in the non-traditional fine wool areas of the RSA. Therefore, in 1999 it was decided to initiate a project where animals from the Grootfontein fine wool flock would be compared to strong wool animals in four non-traditional fine wool areas of the RSA.

EXPERIMENTAL PROCEDURES

In August 2000, the 200 ewes of the Grootfontein fine wool flock, pregnant from rams from the Cradock fine wool Merino stud, were randomly divided into four groups. The four participants were identified by the NWGA and they collected their respective groups during August and September 2000. A group of the participant’s own ewes was also mated at approximately the same time as the fine wool ewes. The first lambs were born during October / November 2000. Grootfontein also supplied the replacement ewes (born in 1999 at Grootfontein) for the 2001 mating seasons. Rams from the Cradock fine wool Merino stud were used as sires in the respective fine wool lines. The ewes of the control line were mated to the rams of the respective participants. The 2004-born animals were the last groups of progeny that were evaluated and this was completed by the end of 2005.

RESULTS AND DISCUSSION

The profit per small stock unit (SSU) for the two groups at each locality is summarised in Table 1. This value for each individual animal was calculated by using the model of Herselman (2004).

Table 1. Profit per small stock unit (SSU)

^a,b,c,d - Values with the same superscript differed significantly for the same participant

It is evident from this table that the fine wool groups at all four localities had a higher (P<0.05) profit per SSU compared to their counterparts. The body weight of the respective groups did not have a large influence on the difference in profitability, due to the fact that the differences in body weight were relatively small or non significant. Therefore, these differences were the effect of the difference in wool production. Due to the fact that the fine wool animals produced less and shorter wool, it is can be deducted that the differences in profitability are probably due to the differences in mean fibre diameter between the respective groups.

CONCLUSION

It is evident from the results of this project that the fine wool animals produced less and finer wool compared to the control animals. This could be expected, as a decrease in fibre diameter would result in a decrease in the fleece weight, as these traits are positively correlated. However, the most important conclusion is that the fine wool animals’ reproduction and body weight is in the same range as that of the control animals. The differences in mutton production between these groups were relatively small and would therefore not have a major effect on the profitability of fine wool versus strong wool sheep farming enterprise. Thus, it is evident from the results of this study that fine wool can be produced in the non-traditional fine wool producing areas of the RSA, where it was thought that fine wool animals would not be able to produce or reproduce, without a negative effect on the profitability of a wool sheep farming enterprise.

ACKNOWLEDGEMENTS

The author want to express his gratitude to Cape Wools of South Africa for funding the project, Dr J.J. Olivier and officials from the NWGA, BKB and CMW for assisting in the execution of the project and the four participating farmers for their contribution to the success of the project.

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ESTABLISHMENT OF A GENETIC POOL OF DUAL PURPOSE SHEEP WITH PREMIUM QUALITY MEAT AND SUPER FINE WOOL UNDER EXTENSIVE CONDITIONS

M.J. Herselman

AIM AND OBJECTIVES

The objective of the study is to establish a genetic pool of dual purpose sheep with premium quality meat and super fine wool under extensive conditions for future evaluation and distribution to the industry.

The objectives of the study are:

·       To establish a genetic pool of dual purpose sheep (150 breeding ewes) which is superior with regard to wool quality (fibre diameter)

·       To increase the numbers of the pool to 400 breeding ewes

·       To improve the wool and meat quality while maintaining other production traits such as reproduction and growth.

INTRODUCTION

The project originated from a request by the wool industry for the establishment of a genetic pool of dual purpose sheep with super fine wool. The wool industry supplied the funds for the initial purchasing of the ewes, as well as the running costs for the first two years. A memorandum of agreement between the Department of Agriculture : Grootfontein Agricultural Development Institute (GADI), the Agricultural Research Council and the Grootfontein Research Trust formalized co-operation between the parties involved in the project. The project started in January 2001 with the screening, identification and buying of ewes for the nucleus flocks at Grootfontein. During 2001 and 2002 a total of 217 ewes were bought from 25 Dohne Merino breeders while 145 ewes were bought from 15 Letelle breeders.  A third group of 51 fine wool Merino sheep from the Cradock fine wool stud was also included and run together with the Dohne and Letelle flocks. The first mating took place during May 2001. Before the onset of the 2004 breeding season, all the original Merino ewes that were kept together with the Dohne and Letelle ewes from the beginning of the project in 2001, were replaced with stud ewes from the Cradock fine wool Merino Stud (Merino) as part of a new project which aims at evaluating an alternative selection index as selection criterion for wool sheep. Only the 40 own-bred Merino ewes (2001 and 2002 progeny) were retained and mated together with 60 Merino ewes from the Cradock fine wool Merino Stud. This report contains information and results that were collected since August 2005. In some cases the results of previous reporting periods are given together with the results obtained during this year for better interpretation.

MATERIAL AND METHODS

All adult animals were shorn during the last week of July 2005. This data were not reported earlier as the analysis of wool samples was not completed in the previous reporting period. One week before the onset of lambing in September 2005, the ewes mated during April/May 2005 were brought in from the veld and placed in small pens (10 ewes/pen) and provided with a pelleted roughage diet. This was done to accommodate accurate parent-offspring identification. Ewes and their lambs were taken back to the veld within two weeks after lambing, except for triplets, which remained in the pens for approximately one month. Data collection on the 2005 progeny and the ewe flock was according to the project protocol. The 2005 lambs were weaned on 10 January 2006 and shorn on 16 January 2006. The 2004 progeny was provisionally classed on 4 November 2005, shorn on 7 November 2005 and the 12-month wool production data collected. Final inspection of the Dohne ewes was performed on 25 January 2006.

During the reporting period, Dohne stud ewes in the national flock with EBV’s for BW>0 kg, CFW>-0.1 kg and FD<-1.2µm were identified and 20 of them were bought from breeders, while more will be bought during the next reporting period. Twelve of these ewes (the other eight were pregnant) were placed in an embryo transfer program together with 18 of the Grootfontein Dohne ewes. These 30 donor ewes were laparoscopically inseminated with semen from ED020410, JG030232, US020134, GF031095 and GF041070. The 287 embryos recovered from the 30 donor ewes were implanted into 136 recipients on 28, 29 and 30 March 2006. A further 60 Dohne stud ewes from the Grootfontein stud were inseminated with semen from ED020410,  JG030232 and US020134, while the 70 remaining Dohne stud ewes were naturally mated to GF031095,  GF041070,  GF041077 and GF041086. In summary, of the 160 Dohne stud ewes, 30 were used as donors in an embryo transfer program, 60 were artificially inseminated, while 70 were naturally mated.

Eighty-seven Letelle ewes were naturally mated to four Letelle rams (032067, 042012, 042044 and 042058) from 30 March 2006, while 104 fine wool Merino ewes were artificially inseminated with semen of three rams (2323040034, 2323040238 and 2323040278) on 4 May 2006.

RESULTS

The number of lambs born alive per 100 ewes mated during the 2005 breeding season was 143, 122 and 129  for Dohne, Letelle and Merino groups respectively. However, mortality rate until weaning was exceptionally high, namely, 16.0, 20.9 and 31.0% for Dohne, Letelle and Merino groups respectively. The reason for these high mortality rates is not known. Body weights recorded for the 2005 progeny are shown in Table 1, while the production data of the adult ewes in the different flocks are shown in Table 2.

Table 1.  Growth results of the lambs born in 2005

Table 2. Production data of adult ewes in the nucleus flocks (2005 ewe flock)

The EBV’s for BW, CFW and FD of the 2004 progeny born in the GF flock were 0.3542 kg, 0.0123 kg and –0.3799 µm, respectively, while the respective EBV’s in the 2005 adult ewe flock were 0.09 kg, -0.004 kg and –0.12 µm. These EBV’s may, however, still contain a large element of inaccuracy as a relatively large proportion of the flock still consists of base population animals.  This is further supported by the unexpected EBV’s for the base population ewes that were estimated to be –0.99 kg, -0.1 kg and 0.48 µm despite the fact that the average selection differential of the ewes bought from the breeders were +2.41 kg and –1.94 µm for body weight and fibre diameter respectively. Furthermore, the average fibre diameter of the adult GF Dohne flock is currently 19.7 µm, which is well below the average of the breed (21.3 µm). An alarmingly high genetic correlation between staple strength and fibre diameter was reported in a congress paper after analysis of data collected in this project.  It was found that for one micron decrease in fibre diameter, staple strength will decrease by 5.2 N/Ktex.

SUMMARY

In general, good progress has been achieved with the project. The unfavourable relationship between fibre diameter and staple strength and the fact that it cannot be ignored in the type of sheep in this project, where average staple strength is relatively close to the lower limit, will severely impact on the genetic progress that might be achieved with regard to selection for fineness.

ACKNOWLEDGEMENTS

Cape Wools SA is acknowledged for their financial support to the project.

PUBLICATIONS

HERSELMAN, M.J., OLIVIER, W.J. & SNYMAN, M.A., 2006. Determining the relationship between staple strength and production and subjectively assessed wool traits. Proceedings 41th SASAS congress, Bloemfontein, 3 – 6 April 2006.

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DEVELOPMENT OF A METHOD FOR THE ESTIMATION OF BREEDING VALUES FOR RESISTANCE/RESILIENCE OF SHEEP TO INTERNAL PARASITES, WHICH WILL BE APPLICABLE UNDER ANY ENVIRONMENTAL CONDITIONS

M.A. Snyman

AIM AND OBJECTIVES

The aim of this study is to develop a protocol for the evaluation of internal parasite resistance of breeding sires, bred in the extensive sheep grazing areas of South Africa where the natural infection of Haemonchus contortus is limited.

The objectives of this study are as follow:

·       To identify effective selection methods for internal parasite resistance in small stock and to apply these methods in practice

·       To compare the natural and artificial challenge methods under intensive as well as extensive conditions in order to evaluate the latter in practice

·       To estimate genetic parameters for indicators of parasite resistance, and correlations of these indicators with production and reproduction traits under South African conditions

BACKGROUND

Internal parasite infection plays an important role in the ability of animals to produce and reproduce to their full capability. Despite various control measures, internal parasites remain one of the largest animal health problems in the small stock industry. To make matters worse, resistance of parasites to available anthelmintics increased drastically during the past decades. The possibility of selection for animals resistant to internal parasites has been investigated and selection programs based on faecal egg counts (FEC) have been implemented in Australia and New Zealand. However, not all questions concerning the practical use of FEC in breeding programs have been answered. For example, repeatability of FEC under various conditions has been shown to be highly variable. Furthermore, many of the ram breeders in South Africa are located in the drier, western parts of the country, with a lower natural parasite infection. As no breeding program will have parasite resistance as its sole objective, the genetic relationship of resistance with other production and reproduction traits should also be considered.

The project started during March 1998. Since then, each year, lambs in each of the following research flocks were infected with third stage Haemonchus contortus larvae at 6-8 months of age for the artificial challenge procedure:

·      Afrino flock at the Carnarvon Experimental Station (1997 to 2005)

·      Dorper flock at the Carnarvon Experimental Station (1998 to 2002)

·      Fine wool Merino stud at Cradock Experimental Station (1997, 1998, 1999, 2001)

·      Merino stud at GADI (1997, 1998, 1999, 2001)

·      SA Mutton Merino flock at Potchefstroom Livestock Centre (2002)

Faecal egg counts (FEC), haematocrit (HEMA) and Famacha©-scores (FAM) were done 28 days after infection.

It was decided to include the natural challenge method in the project from October 2000, in order to be able to compare results obtained with artificial challenge with those obtained with natural parasite infections. This part is done on lambs from the Fine wool Merino stud at Cradock Experimental Station, and since 2002 on the Potchefstroom Mutton Merino flock.

CONCLUDING REMARKS

At this stage of the project, the following conclusions could be made:

·     For the purpose of developing a protocol to evaluate breeding values for resistance of sires born in the extensive sheep grazing areas, the natural challenge procedure will definitely not be an option. This is largely due to the low and unpredictable rainfall, with the resultant variable parasite challenge, which makes this procedure unreliable for use at a specific time each year.

·     Furthermore, using breeding values for parasite resistance based on the Famacha©-system, will also not be feasible for the evaluation of breeding sires in the extensive areas. The reason for this is that the recording period is too long before differences between animals are expressed. Furthermore, employing the Famacha©-system after natural challenge is unfeasible, as mentioned in (1). To employ the Famacha©-system after artificial challenge would be unpractical, as faecal egg counts can already be recorded on day 28 after infection, after which the test can be finished. The data collected during this study, however, confirm that the Famacha©-system is an excellent management tool to identify animals that need anthelmintic treatment.

·     For the most important part of the study, where animals selected in a dry area (Carnarvon) are evaluated under a higher rainfall area (Potchefstroom), much more data still need to be recorded.

·     Although HEMA has a high genetic correlation with FEC, it is more difficult and expensive to measure, while other factors could also influence the anaemic status of an animal. Therefore, HEMA as such, would not be a feasible selection criterion as indicator of resistance.

·     For the purpose of developing a protocol to evaluate sires born in the extensive sheep grazing areas, FEC after artificial challenge procedure seems the best option as selection criteria for resistance against internal parasites. The following should be taken into account:

-         The availability of a viable, non-resistant strain of H. contortus is an important issue, which should be addressed as soon as possible.

-          Animals should receive a pre-test dose of larvae to activate their immune response.

-         The level of infection should be high enough to ensure that genetic differences can be expressed.

·     The part of the project that involves the natural challenge procedures with the fine wool Merino flock at Cradock and the Mutton Merino flock at Potchefstroom will be terminated.

·     That part which involves the evaluation of resistance in the two different environments (Carnarvon and Potchefstroom) will continue for at least another five years.

ACKNOWLEDGEMENTS

The project leader wants to convey her sincere appreciation to the following people for their valuable contribution in the execution of the project:

PUBLICATIONS

SNYMAN, M.A., VENTER, Y., VAN HEERDEN, M. & BUYS, T., 2006.  Internal parasite resistance of sheep evaluated in two different environments. Proceedings 41th SASAS congress, Bloemfontein, 3 – 6 April 2006.

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INVESTIGATION INTO THE SELECTION CRITERIA OF MERINO SHEEP

W.J. Olivier

AIM AND OBJECTIVES

The aim of this study is to evaluate the effect of two different breeding strategies on the wool production and wool characteristics of Merino sheep.

The objectives of this study are:

·      To evaluate the effect of two different breeding strategies to decrease fibre diameter on the wool production and wool characteristics of Merino sheep

·      To increase body weight and staple length

·      To maintain or increase clean fleece weight

·      To make rams available to the wool industry through the annual ram sale of Grootfontein

·      To supply rams to the communal areas of the Eastern Cape

·      To use the animals from this study for the training of the students of the Grootfontein Agricultural College

INTRODUCTION

The increase in the demand for fine and super fine wool, as well as the price premium paid for fine wool during the 1990’s, caused a shift towards the production of fine wool in an increased number of flocks in South Africa. Fibre diameter can be decreased either through within flock selection or through the use of genetic fine wool rams.

One of the perceptions with regard to fine wool production is that the use of genetic fine wool animals on strong wool animals will have a negative effect on the quality of the wool. It is assumed that the progeny of these animals will have under-crimped wool, as well as a large variation over the fleece.

It is therefore important for the Merino industry of South Africa to quantify what possible effects these two breeding strategies may have on wool production and characteristics of Merino sheep. Two selection lines, namely a fine wool and a control line, were therefore established within the Grootfontein Merino stud in 2001. The same selection objectives are used in both lines. The only difference between the two lines is that genetic fine woolled rams from the Cradock fine wool Merino stud are mated to the fine wool line ewes, while the control ewes are mated to rams selected for fineness from the control line.

RESULTS AND DISCUSSION

The genetic trends for body weight, clean fleece weight, fibre diameter, staple length and relative economic value are depicted in Figure 1. The progeny of the C-line were heavier (P<0.01), while the F-line progeny produced finer (P<0.01) wool. There were no significant differences in clean fleece weight, staple length or relative economic value between the respective lines.

CONCLUSION

It is evident from the results of this study that the 2004 progeny of the F-line had a lower coefficient of variation compared to their contemporaries at 16 months of age. The F-line ram and ewe lambs had stronger staples than the ram and ewe lambs of the C-line. Furthermore, the results of this study support the negative relationship between coefficient of variation and staple strength.

The rams that were selected in 2005 for breeding purposes will have a positive effect on the breeding objectives of this stud with regard to body weight (C-line), mean fibre diameter and staple length. These rams will also increase the relative economic value of both lines.

Figure 1. Genetic trends for body weight, clean fleece weight, fibre diameter, staple length and relative economic value

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EVALUATION OF SELECTION CRITERIA FOR BOER GOATS UNDER EXTENSIVE CONDITIONS

W.J. Olivier

AIM AND OBJECTIVES

The aim of this study is to investigate and evaluate selection criteria currently used in the Small Stock Improvement Scheme (SSIS) of the Agricultural Research Council: Livestock Business Division: Animal Production (ARC:LBD Animal Production) for Boer goats under extensive conditions.

The objectives of this study are:

·         To determine whether selection based on the traits measured in the SSIS would result in increased lifetime production and reproduction efficiency in Boer goats

·         To linear assess subjective traits included in the breed standards and to estimate heritabilities and correlations of these traits with production and reproduction traits

·         To linear assess the number of teats and to estimate heritability and correlations of this trait with production and reproduction traits, in order to investigate the possible inclusion of number of teats as a selection criterion for ram selection

·         To construct a viable breeding plan for Boer goats based on the results of this project

·         To implement this breeding plan in the industry

·         To establish a database for the estimation of accurate genetic parameters for Boer goats

INTRODUCTION

Red meat is one of the most important sources of protein for the population of the RSA. Due to the limited natural resources in many of the small stock producing areas of the RSA, efficiency of meat production should be increased within the available resources, in order to utilise the existing resource optimally and also to simultaneously conserve it for future generations. In order to achieve this goal, selection should be aimed at increasing the efficiency of meat production and more specific goat meat production. The ARC:LBD (Animal Production) has established the SSIS in order to provide farmers with a selection tool with which the efficiency of goat meat production can be improved. The purpose of the SSIS is to improve the overall productivity of the breed through the identification of high producing animals and to select these animals as the parents of the next generation (SSIS: Boer goat performance testing plan, 1998). The SSIS incorporates the production traits, namely 100-day weaning weight and 270-day body weight, as well as reproduction traits. In other words, the producer will receive a growth and reproduction report from which he could make his selection on weaning weight, body weight and ewe productivity. One of the objectives of this study is therefore to investigate and evaluate selection criteria currently used in the SSIS for Boer goats under extensive conditions.

Furthermore, on several occasions the question was raised by breeders regarding the importance of number of teats when breeding rams are selected. The breed standards of the Boer Goat Breeders’ Society specify the different types of teat arrangements that are acceptable and not acceptable for both rams and ewes. It is therefore important to determine the heritability of the number of teats, as well as the correlation of this trait with production and reproduction traits, in order to decide whether it should be included in the performance testing scheme.

Stud breeders are responsible for the genetic progress made in any breed, as superior genetic material is distributed down to the commercial and small-scale farmers. A broad spectrum of Boer goat farmers (stud, commercial and previously disadvantaged or small scale farmers) will therefore benefit from the results of this study.

This project commenced in 2004 on the farms of six Boer goat breeders, Koopmansfontein Experimental Station and the Boer goat flock at Grootfontein Agricultural Development Institute.

RESULTS AND DISCUSSION

It is evident from the figure that the largest proportion of the animals in these flocks had only one teat or one teat with a non-functional teat on either halves of the udder. Furthermore, it is visible in these figures that there is variation with regard to teat score, especially in the Grootfontein and Koopmansfontein flocks.

Figure 1. Teat scores of the 2005-born kids of Boer goat flocks at Grootfontein, Daniëlskuil and Griekwastad and the adult does at Koopmansfontein

WAY FORWARD

The results obtained from this study will assist the Boer Goat Breeders’ Society in decision making with regard to the culling on certain teat types in both the rams and ewes. Furthermore, the correlations between the production, reproduction and type traits will also be of aid in constructing a breeding plan to improve the profit of Boer goat breeders and farmers.

The progress report will be discussed with the participants at the annual meeting that will be held in Kimberley in September or October 2006. The progress report will also then be discussed with the Society.

ACKNOWLEDGEMENTS

The author wants to express his gratitude to the Department of Agriculture and Land Reform of the Northern Cape Province and the participating farmers for their contribution to the success of the project.

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INVESTIGATION INTO THE RELATIONSHIP BETWEEN MILK PRODUCTION OF GRAZING EWES AND MATERNAL BREEDING VALUES FOR EARLY GROWTH TRAITS IN THREE SOUTH AFRICAN SHEEP FLOCKS

M.A. Snyman

AIM AND OBJECTIVES

The aim of this study is to evaluate the use of maternal breeding values for early growth traits as alternative or additional selection criterion for improved growth efficiency in slaughter lamb production enterprises.

The objectives of this study are as follows:

·       To determine milk production potential of woolled sheep ewes under different grazing conditions

·       To estimate genetic parameters for milk production of these ewes

·       To determine the relationship between milk production of ewes and direct and maternal breeding values, as well as actual weaning weight of their lambs in three sheep flocks, under different grazing conditions

·       To determine the relationship between maternal breeding values for early growth traits of sires and milk production of their daughters, as well as growth performance of the daughters’ lambs

BACKGROUND

Body weight has always been one of the important traits considered during selection of both replacement ewes and rams in many wool and mutton sheep breeding enterprises. Using body weight as the sole selection criterion for improved early growth rate in lambs, could have the following detrimental effects: Firstly, overall efficiency of pre-weaning growth could be negatively influenced due to a possible negative genetic relationship between additive direct and additive maternal components of traits affected by both direct and maternal effects. Early growth traits in sheep all fall within the latter category. Secondly, as body weight at all ages is highly genetically correlated, increasing body weight at an early age will also increase mature body weight. This will have a negative effect on overall profitability of the enterprise, if the increase in body weight is not accompanied by an increase in lambing percentage or a net increase in income from wool production.

It is therefore important that selection emphasis should be shifted from body weight to include some measure of maternal performance as well, be it direct maternal breeding values for early body weight, such as weaning weight, or milk production potential of the ewe.

The project commenced in 2004. During the first year of the study at each location, repeated milk recordings on a selected sample of the ewe flock were done, in order to obtain the average shape of the lactation curves for the ewes in each of the experimental flocks. During 2004, ewes in the Carnarvon Afrino flock, as well as the Dohne Merino flock at GADI, were milked.  Ewes in the Cradock fine wool Merino flock and the Merino ewes in the high and low reproduction lines at Elsenburg were milked during 2005 to obtain the average shape of the lactation curves of these two flocks. During the September 2005 lambing season, milk production of all ewes that lambed in the Carnarvon Afrino flock was determined at three and twelve weeks of lactation.

CONCLUDING REMARKS

Lactation curves for different woolled sheep flocks under different grazing conditions have been obtained. Differences in total milk production were evident among the flocks, which concurred with the different grazing conditions. The lactation curves obtained in this study are in line with those published for other grazing sheep ewes of various breeds.

As this project has just started, no reliable conclusions with regard to the other project objectives could be made at this stage. The following was evident from the data collected during the 2005 lambing season on the Carnarvon Afrino ewes:

·       Very large standard errors were obtained for most of the correlations, indicating large variation in the respective traits. More data are therefore needed to estimate accurate and reliable correlations.

·       Total milk production of the ewe was positively correlated with total weight of lamb weaned, individual weaning weight of lambs, EBV-weaning weight of lamb and maternal EBV-weaning weight of the lamb.

·       Maternal breeding value for weaning weight of the dam has a positive correlation with individual weaning weight of her lambs, as well as direct and maternal EBV-weaning weight of her lambs.

The project will continue at Carnarvon, Cradock and Elsenburg with the yearly recording of milk production of all ewes that lambed in each flock.

ACKNOWLEDGEMENTS

The project leader wants to convey her sincere appreciation to the following people for their valuable contribution in the execution of the project:

PUBLICATIONS

SNYMAN, M.A., HERSELMAN, M.J., CLOETE, S.W.P., GRIESSEL, P.J., VAN HEERDEN, M., BUYS, T. & GREYLING, A.C., 2006. Milk production of grazing wool sheep ewes. Proceedings 41th SASAS congress, Bloemfontein, 3 – 6 April 2006

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ESTABLISHMENT OF A BIOLOGICAL BANK FOR THE ANGORA GOAT POPULATION IN SOUTH AFRICA

M.A. Snyman

AIM AND OBJECTIVES

The aim of the project is to establish a biological (DNA) bank for Angora goats in South Africa. A DNA bank is essential for the application of more recent techniques for studying genetic variation, identification of genetic disorders and the search for quantitative trait loci.

The objectives of the project are:

·       Collect blood samples from all animals in the participating flocks

·       Collect production and reproduction data on all animals in the participating flocks

·       Store blood samples in Eppindorf tubes and on FTA Classic cards

·       Extract DNA of all samples and store

·       Create and maintain a data base with all relevant genetic, production and reproduction data

BACKGROUND

This project is a combined initiative between Grootfontein ADI, the University of Pretoria and Angora goat producers. This project commenced in January 2005.

The selection of most farm animal species is practiced according to quantitative theory.  A relatively large and accurate system of performance records has been established over the years and proved to be essential for estimating breeding values.  The development of molecular techniques and the mapping of the genomes of most farm animals have created new means for research regarding genetic diseases and disorders, as well as performance traits. Advances in biotechnology, especially in the molecular field, have provided new opportunities for animal geneticists and breeders.  Since the initiation of the Human Genome Project 13 years ago, projects have been established to map the genomes of most farm animal species, including the goat.  At present 262 genes, 694 loci and 1104 DNA markers are available on the goat map.  Quantitative trait loci (QTL) are referred to as loci affecting quantitative traits.  In farm animals most of the performance observed in traits of economic importance is the result of quantitative variation.  In order to identify a QTL for a specific trait, many animals have to be genotyped for a large number of markers on different chromosomes.  Phenotypic data (which has already been collected) and genotypic data (which will be obtained from DNA) are combined for locating the most likely location on the chromosome responsible for the specific trait.

The search for QTLs is a long-term process and at least two to three generations of different families should be included.  It is therefore essential to start collecting DNA samples for DNA analyses. The goat genome map is under construction and as more markers become available, more opportunities arise for appropriate molecular research of the Angora goat.

RESULTS AND DISCUSSION

Participants

The following five Angora goat producers are participating in this project:

Jansenville fine hair flock – Jansenville Experimental Station, Jansenville

Cape Angora Top Tier – Mr Roelof Retief, Boksfontein, Murraysburg

Studs 116 & 217 – Mr Arthur Short, Wheatlands, Graaff-Reinet

Studs 142, 154 &  317 – Mr Ray Hobson, Baroe, Steytlerville

Stud 248 – Mr Deon Barkhuizen, Rooiklip, Uniondale

Blood sample collection and DNA extraction

During January 2006, blood samples were collected into 5 ml EDTA vacutainer blood collection tubes from all 2005-born kids on the farms of the participants. Blood samples were also collected at two farms during January 2006 of some ewes that were not sampled the previous year. The number of goats sampled to date at each participant is summarized in Table 1. A total of 4880 blood samples were collected. After collection, 1.5 ml blood from each goat was transferred to small Eppendorf tubes for storage for future use. These, as well as the remainder of the blood in the vacutainer tubes, were frozen. The remaining blood was taken to the University of Pretoria, where DNA was extracted, and another sub-sample (100 µl) transferred to Whatman FT Classic cards for storage.

Table 1. Number of blood samples collected to date

Production and reproduction data

Production and reproduction data collected on the same flocks over the past four years with the kid mortality project are also available for this project. The following production data were recorded on the participating flocks during the reporting year:

·      Full pedigrees

·      Body weight of ewes before mating

·      Reproduction data of all ewes

·      Birth weight of kids

·      Body weight of kids at weaning

·      Body weight of ram and ewe kids at 8 months of age

·      Fleece weight and fleece sample of ram and ewe kids at second shearing

·      Body weight, fleece weight and fleece sample of young ewes at third shearing at 16 to 18 months of age

·      Body weight, fleece weight and fleece sample of ewes at the winter shearing

These data will be entered, together with the genetic data, into the database created for this purpose.

CONCLUDING REMARKS

The project will continue for the next six years.

·      To date, 4880 blood samples have been collected, DNA extracted and DNA and additional blood samples stored for future analysis

·      All the relevant data of all the samples received have been entered into the database developed for this purpose 

·      A QTL search will be conducted on a ten-family, half-sib design, with each sire producing 120 offspring over a three-year period. A total of 56 markers will be tested for this purpose.

ACKNOWLEDGEMENTS

The following people / institutions are acknowledged for their contribution to the project:

·      Participating breeders

·      Mohair South Africa for funding of the project

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BREEDING MERINO SHEEP FOR INCREASED PROFIT PER SMALL STOCK UNIT

W.J. Olivier

AIM AND OBJECTIVES

The aim of this study is to evaluate profit per small stock unit (SSU) as a selection criterion in woolled sheep.

The objectives of this study are:

·       To evaluate profit per SSU as a selection criterion for woolled sheep

·       To breed Merino sheep for increased income per SSU

·       To supply the Eastern Cape Department of Agriculture Livestock Improvement Program with genetic material to improve the profit per SSU in the communal areas

·       To make animals available for student and farmer training.

INTRODUCTION

To ensure continued success of both commercial and communal wool farmers, it is important that the animals with the highest profit per SSU can be identified, rather than the animals with the highest gross income per head. This will result in the selection of animals that will increase the profit per hectare of a wool farming enterprise. Furthermore, it will also ensure that the wool industry of South Africa produce wool and mutton at optimal levels without increasing the pressure on the natural resources.

Two flocks are used for this experiment. One flock is kept under intensive conditions on irrigated pastures at Cradock Experimental Station (Cradock), while the second flock is kept under extensive conditions on natural pastures at Grootfontein Agricultural Development Institute (Grootfontein). Both these flocks are selected for increased profit per SSU, according to Herselman (2004).

GENETIC TRENDS

The genetic trends for body weight, clean fleece weight, fibre diameter, staple length and relevant economic value are depicted in Figure 1. It is evident from this figure that there is a positive trend in the relative economic value that includes reproduction.

CONCLUSION

The rams that were selected in 2005 for breeding purposes will have a positive effect on the breeding objective of both these flocks. The 2005 progeny will be performance tested at the end of 2006. The conception rate at both localities was lower than that of the previous year. The lower than normal rainfall during the first part of 2005 at Grootfontein could possibly have contributed to the lower conception. Despite the lower conception rates, the fecundity of both flocks was higher. This countered the effect of the lower conception rate on the number of lambs born to some extent in the Grootfontein flock, while more lambs were born in the Cradock flock compared to the previous year.  The low survival rate of the Grootfontein lambs can possibly be ascribed to the above average rainfall during the first part of 2006, especially during January and February. This will have a negative effect on the number of ewes available for replacement during 2007. This problem can possibly be solved by selecting replacement ewes from the Cradock flock, as more than ample replacement animals would be available due the higher fecundity in this flock during 2005. The project is running according to the project proposal.

ACKNOWLEDGEMENTS

The author want to express his gratitude to Cape Wools SA for funding of the project, the Department of Agriculture of the Eastern Cape, Dr J.J. Olivier and officials from BKB and CMW for assisting in the execution of the project and for their contribution to the success of the project.

Figure 1. Genetic trends in the Cradock fine wool Merino stud for body weight, clean fleece weight, fibre diameter, staple length and relative economic value

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INVESTIGATION INTO REPRODUCTION AND KID MORTALITY OF SOUTH AFRICAN ANGORA GOATS

M.A. Snyman

AIM AND OBJECTIVES

The aim of this study is to identify the factors contributing to a low reproductive rate and high kid mortality in South African Angora goats.

The objectives of the project are:

·       Collect data on body weight and reproduction of ewes

·       Collect data on growth performance and hair production of kids

·       Collect data on causes of kid mortalities

·       Collect data on fertility of rams

·       Collect data on all management aspects, such as management during mating and kidding, supplementary feeding practices, animal health practices and weather conditions

·       Analyze data and identify important factors contributing to a low reproductive rate and high kid mortality in South African Angora goats.

BACKGROUND

Reproduction and lamb survival rate are the most important traits influencing income in all small stock breeds, including woolled sheep and Angora goats. Kids and young goats produce the most expensive mohair and a high weaning percentage will ensure a large proportion of kid and young goat mohair. High reproductive and kid survival rates also contribute to higher selection intensity, i.e. when more young goats are available at selection age, selection could be stricter and genetic progress could be quicker.

The poor reproductive performance and high kid mortality rate of Angora goats are well documented. There are numerous factors that contribute to the actual number of kids born per ewe that was put to the rams. Factors influencing the number of kids weaned or the survival rate of kids, include birth weight of the kid, genetic influences, mothering ability and milk production of the dam, adverse environmental or feeding conditions, disease and predators.

Various surveys had been done in the South African Angora goat industry, which assessed different aspects of Angora goat farming (Van Rensburg, 1962; Terblanche, 1988; Geyer, 1996). While some of these studies dealt with possible reasons for kid mortality, they did not cover the possible causes of reproductive failure. The purpose of this study is to identify the factors contributing to a low reproductive rate and high kid mortalities in Angora goats. In order to determine the factors responsible for the unsatisfactory reproductive performance, it is essential that all possible contributing influences be investigated. Therefore, in order to assess the problem, an intensive study of Angora flocks varying in reproductive rate and management practices, was done. The study was done on 10 Angora goat studs and the two experimental flocks at the Jansenville experimental station. The project started with the September 2000 kidding season.

The 2004 kidding season was the last one to be recorded. Management data, as well as data on post-weaning mortalities, growth performance and hair production of the 2004-born kids were recorded during the 2005/2006 report year. Data collected during the survey period are being analysed and a final report will be submitted at the end of 2006. Most of the analyses on body weights and growth rate of the kids, as well as kid mortalities, have been done and will be presented in this report. Data analyses on breeding values for growth traits, fleece weights, ewe age, body weight and reproduction, as well as management practices, are underway and will be reported on in another report.

CONCLUSIONS

The project is completed and the final report will be submitted at the end of 2006. Participating breeders were positive about the project and gave excellent co-operation.

Summary of growth performance of kids

The following conclusions can be made:

·       Pre-weaning growth rate of ram and ewe kids is satisfactory.

·       The effect of different pre-weaning treatments (supplementation) did not seem to be carried over to body weights at 12 and 16 months of age in most cases. The viability of this should, however, be investigated further, as no suitable control groups were present. For example, those groups that did receive supplementation could have performed much worse up to 16 months of age if they did not receive any supplementation.

·       Post-weaning growth rate of those kids (ram and ewe) that did not receive supplementary feeding after weaning, are unacceptable.

·       The poor growth rate of especially ewe kids after weaning till 12 months of age is a serious problem that should be addressed, as it directly influences the reproductive ability of the young ewes.

·       Data recorded during this study on the retarded growth of kids after weaning, have already led to an additional project on the investigation of different weaning practices for Angora kids.

Summary of kid mortalities

The following conclusions can be drawn:

·       It is clear that pre-weaning mortality rate in the Angora studs included in this study is not exceptionally high (average 11.5 %). In fact, it compares favourable with that recorded for most sheep breeds.

·       The most important single cause of kid mortalities was vermin (39.0%), while a combination of small, unthrifty kids who needed help suckling, ewes having little or no milk, thick teats and udder problems and ewes discarding their kids (problems due to mothering ability), was responsible for 35.7% of pre-weaning mortalities.

·       Despite large differences in mortality rate recorded between sires within flocks (0 to 50%), a heritability of 0.04±0.01 was estimated for pre-weaning mortality rate. This could probably be explained by the fact that many of the causes of mortality have no genetic background from the sire’s side. However, causes such as small, unthrifty kids, illness and deformed lambs have a genetic basis and should be addressed as such.

·       The relationship between birth weight and mortality rate in Angora goats are more curvi-linear than “U” shaped, although kids at the lighter as well as heavier ends of the scale tend to have lower survival rates, except for twin born kids.

·       More than 45% of kid mortalities, where ewes lost three kids over the recording period, were due to small, unthrifty kids who needed help suckling, ewes having thick teats and udder problems, ewes having little or no milk or ewes discarding their kids. This indicates that these problems will occur repeatedly in the same ewes. Ewes experiencing these kinds of problems should preferably be eliminated, especially ewes with teat or udder problems.

From the data collected over the past 5 years, the following problem areas have been identified:

·      The most important single cause of kid mortalities was vermin (39.0%), while a combination of small, unthrifty kids who needed help suckling, ewes having little or no milk, thick teats and udder problems and ewes discarding their kids (problems due to mothering ability), was responsible for 35.7% of pre-weaning mortalities.

·      Nearly 20% of the ewes did not reproduce. Of these, 9% had lost their fetuses between scanning and kidding. This aspect is usually not taken into account when the relatively poor weaning percentage of Angora goats is under discussion. High kid mortalities are usually blamed for the low weaning percentage.

·      The low reproductive rate of especially young ewes is an aspect that needs further investigation.

·      The poor growth rate of kids after weaning, and especially those of ewe kids from weaning till 12 months of age, is a serious problem that should be addressed, as it directly influences the reproductive ability of the young ewes.

·      Data recorded during this study on the retarded growth of kids after weaning, have already led to an additional project on the investigation of different weaning practices for Angora kids.

ACKNOWLEDGEMENTS

The following people / institutions are acknowledged for their contribution to the project:

·      Participating breeders

·      Mohair South Africa for funding of the project

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BREEDING PROGRAM FOR LIVESTOCK GUARDING DOGS

C. Stannard

AIM AND OBJECTIVES

The aim of this project is to breed livestock guarding dogs (LGD’s) for evaluation under South African conditions.

The objectives of this project are:

·       to obtain a breeding group of Anatolian Shepherd dogs

·       to supply puppies to be placed with farmers

·       to evaluate the puppies under working conditions.

BACKGROUND

Livestock losses as a result of predators, stray dogs and stock theft is a major problem facing small stock farmers throughout South Africa. Livestock losses in the small stock industry in South Africa due to predators amounts to approximately 1 million sheep per year (Bekker, 2001).  For the past few decades, this problem has been a discussion point on every forum in the small stock industry.  The National Problem Animal Policy Committee was established with the aim to guide the control of predators and to ensure that the control methods employed are correctly applied.  Through the years, different methods of control have been used such as poisoning, traps, hunting dogs and electric fences. From practice it is also evident that professional predator hunters and hunting clubs have limited success in the control of problem animals. 

An additional method for predator control is the LGD’s.  LGD’s are being used with great success against predators in the USA, Britain, Australia and Namibia, as well as the countries of origin of these dogs. There are eight different breeds of dogs that can be used as LGD’s.  Of these breeds, the Anatolian Shepherd dog is widely considered to be the best, owing to its size, aggressiveness, loyalty, braveness and working ability. The dogs protect the herd by the following methods: patrolling, barking, urine marking, chasing and attacking the predator if it threatens the herd.

RESULTS

The breeding program started at Grootfontein Agricultural Development Institute (GADI) in 2002 with five dogs.  At the end of the previous reporting period, there were eight animals in the program at GADI. During the past year one of the females was lost due to the parvo virus, while one male dog was donated to the program by RAMSEM.   Therefore, the project still has eight animals in its breeding program, three males and five females.  During the reporting period a few other breeders made use of Grootfontein’s males.  The numbers of puppies that were born, died and placed with farmers are summarized in Table 1.  It is evident from this table that four of the puppies died before placement.  These deaths were the result of the parvo virus.  Therefore, only fifteen puppies could be placed with farmers after vaccination and de-worming.  Each farmer received guidelines for raising and training the puppies. 

Table1.  Number of puppies born, died and placed with participants

The dogs placed with farmers during previous reporting periods were evaluated during this reporting period. The evaluation results are summarized in Table 2. It is evident from the evaluation results that most of the dogs are working as expected and only at one location major problems with the dog were experienced.  At this location the dog chased lambs, roamed and kept ewes away from their newborn lambs.  Differences in working performance of dogs among participants can possibly be ascribed to differences in the way that farmers raised and handled their dogs, as well as differences in bloodlines of the different litters.  Minor problems at some localities, such as  personality deviations of dogs as well as the time spent with the dog by the owners, occurred.

Table 2.  Evaluation results of dogs placed with farmers during previous reporting periods.

CONCLUSION

The changes made to the management of the dogs had led to an increase in the number of puppies placed with farmers.  This is a very positive outcome obtained during the reporting period. Due to the fact that not enough data is available, it is not possible to make any conclusive remarks from the evaluation of the dogs.  It is, however, possible to make some remarks with regard to the progress of the project.  It is evident from the results that participants should take care that the dogs be handled in accordance with the guidelines of the project.  Furthermore, bloodlines that consistently breed dogs with a poor working ability or behavioral problems should be identified and eliminated. The project is running to satisfaction and the results, be it positive or negative, is helping to establish a working knowledge of these dogs under South African conditions.

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A SURVEY ON THE EFFECTIVENESS OF DIFFERENT PROBLEM ANIMAL CONTROL METHODS IN THE SMALL STOCK PRODUCING AREAS OF SOUTH AFRICA

M.J. Herselman

AIM AND OBJECTIVES

The aim of this project is to investigate the extent of problem animals and the effectiveness of the control methods of problem animals in the small stock producing areas of South Africa and to investigate the use and effectiveness of livestock guarding dogs, as a method of problem animal control.

The objectives of the study are:

·      To record sheep and goat mortalities under farming conditions in South Africa

·      To determine factors that contribute towards losses of sheep and goats to problem animals

·      To determine the effectiveness of control methods of problem animals

·      To determine the impact of introducing livestock guarding dogs on the predation problem

BACKGROUND

Loss of livestock to predation remains one of the major problems experienced by sheep and goat farmers.  Many ways of dealing with the problem are practiced by farmers and new techniques are introduced on a regular basis.  The effect of these methods used by farmers differs from region to region and even from farm to farm.  The farmers also use there own methods for which there are no records available.  The use of livestock guarding dogs (LGD’s) is a proven technique in other parts of the world and is now also gaining popularity in South Africa. This project, to obtain reliable information on the extent of livestock losses from individual producers and for the evaluation of the impact of different problem animal control methods, started in 2003. In addition, Anatolian Shepherd dogs are also introduced into the project as they become available from the Grootfontein Research Trust breeding program.  Farmers buy these dogs at a subsidized price and integrate them into their flocks as prescribed.  The data on the effect of these dogs on stock losses are then integrated into the database.  In this way it is possible to study the efficiency of these dogs. Twenty-two Anatolian Shepherd dogs were already placed with participants during previous reporting periods.

EXPERIMENTAL PROCEDURES

Currently the survey covers 43 farms throughout South Africa.  For the purpose of this report, data collected during the third year of the survey (2005) are reported. Each farmer completed an annual questionnaire in which particulars of his farming enterprise, neighbouring farms, as well as livestock numbers were requested. Losses of livestock and predators killed were reported by means of completing a monthly questionnaire.  During the reporting period, 15 more puppies (8 weeks of age) were placed with participating farmers.

RESULTS

The numbers of animals in the survey and livestock losses due to different causes are shown in Table 1. From Table 1 it appears that the predator problem is mainly associated with unweaned lambs and that the stock theft problem is small relative to the predation problem. The impact of introducing livestock guarding dogs on the losses to predators is depicted in Figure 1.

From Figure 1 it is evident that the introduction of livestock guarding dogs had a significant impact on the number of lambs caught by predators. On the 10 farms where livestock guarding dogs were introduced during 2004, the percentage of lambs caught before weaning decreased from 7.6% in 2003 to 2.6% in 2005. After weaning, the percentage of lambs caught decreased from 2.9% to 0.6% from 2003 to 2005.

Table 1.  Livestock numbers and the mortality rate (%) due to different causes on survey farms

Figure 1.                 The effect of introducing livestock guarding dogs on the number of lambs caught by predators before (left) and after (right) weaning

EVALUATION OF PROJECT STATUS

1.             Although individual cases of extremely high livestock losses occur, the extent of the predator problem appears not to be a general threat to small stock production in South Africa. Data collected so far indicate that predators kill approximately 4% of all lambs before weaning and another 1% after weaning.

2.             The most significant result from this study is the significant impact of livestock guarding dogs on the predation problem.

3.             A large proportion of the initial participants in the project ceased to send the monthly questionnaires back and on telephonic follow-up indicated that they are not interested anymore. Currently, 43 farmers are participating in the project. Due to the poor co-operation from farmers, the project will in future only be utilised for the evaluation of livestock guarding dogs. For this, a limited number of participants (current participants plus a few more) will be phoned monthly (as in the past) to obtain the relevant information. This project and the breeding program of the dogs will also be combined into one project.

ACKNOWLEDGEMENTS

The following people / institutions are acknowledged for their contribution to the project:

·                     Participating breeders

·                     Cape Wools SA for financial support

·                     Grootfontein Research Trust for providing the livestock guarding dogs

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INVESTIGATION INTO THE CAUSE, PREDISPOSING FACTORS AND EFFECTIVE TREATMENT OF SWELLING DISEASE IN SOUTH AFRICAN ANGORA GOATS

M.A. Snyman

AIM AND OBJECTIVES

The aim of this study is to identify the causative agent(s) responsible for swelling disease in South African Angora goats.

The objectives of this study are:

·       To carry out trials to investigate and identify the predisposing factors as well as the causative agent(s) responsible for swelling disease

·       To identify the most effective treatment for swelling disease.

BACKGROUND

During the early 1970’s Angora goat farmers reported a condition in their goats, characterized by the sudden onset of severe subcutaneous oedema of the lower body parts. Some goats died of the condition, while others seemed to recuperate spontaneously. According to various internal reports of the Regional Veterinary Laboratory at Middelburg (EC), numerous trials were conducted to investigate the cause of this disease. However, no conclusive evidence was found as far as the cause of the disease is concerned. Therefore, results of these trials were not published.

Outbreaks of swelling disease still occur periodically and some losses are still experienced by Angora goat producers. No definite cure is known; various farmers practice different treatments, not all of which are always successful. As a result, delegates at the 60^th Annual General Congress of the Mohair Growers’ Association of South Africa unanimously accepted a resolution that purposeful research should be carried out on the cause, treatment and prevention of swelling disease in various areas among all age groups of Angora goats in South Africa.

From all the information available on swelling disease in Angora goats, it is obvious that it is a complex condition, of which little is known regarding the mechanisms involved in the initiation and course of the disease. Results obtained thus far with the present study indicated that, although O. circumcincta infection has been listed as one of the predisposing factors for the disease, O. circumcincta infection alone does not cause swelling disease. The results of this study further indicated that higher dietary protein levels could possibly aid in the prevention of swelling disease. The possibility that there are different clinical forms of the disease should also be kept in mind, as reported cases differed considerably in the extent of oedema, as well as with regard to other associated parameters and the duration and outcome of the disease.

CONCLUSIONS

·      Part 1 of Phase 1 of the project is dependent upon swelling disease outbreaks and the reporting thereof by the farmers. For retrospective pathology, it is essential that affected goats should not be transported for a long distance and that samples be taken within 15 minutes of death. As suitable conditions for post mortem examinations are not present on most farms, most of the reported cases could not be used for this specific investigation. However, an outbreak of swelling disease occurred on a farm just outside Middelburg during March 2006. Samples from these animals were obtained for retrospective pathological investigations at Onderstepoort. The results of this study are not available yet.

·      A questionnaire, investigating the epidemiology of swelling disease was drawn up, and sent out to 500 Angora goat producers on 7 March 2005. Of all the questionnaires sent out, 32.2 % were returned (161 questionnaires). Of these, 65% or 100 respondents have encountered swelling disease on their farms, while 35% or 56 have never seen the disease. Five respondents did not farm with Angora goats anymore.

·      From the questionnaires, the following could be deduced:

-         The highest incidence of swelling disease was recorded for the Somerset East, Cradock, Uniondale, Jansenville, Middelburg, Cathcart and Prince Albert districts.

-         Of those respondents who had swelling disease on their farms, 55% reported a yearly occurrence of the disease, while at 45% of the farms it occurred only sporadically. It is furthermore evident that the highest incidence of the disease occurred during the summer and winter months, with the lowest occurrence during spring.

-         The morbidity rate, or percentage of animals affected and recovered, was 4.47% on average for all farms where swelling disease occurred. The mortality rate was low; 0.46% of affected animals succumb to the disease or its complications.

-         The highest incidence of swelling disease was recorded for the age groups weaning to 12 months of age (80%) and 12- to 18 months of age (73%).

-         The highest incidence of swelling disease occurred on planted pastures, followed by mixed veld, in “vleie” and on grass veld. It seems that veld types associated with higher moisture conditions and those with lower protein values, are those on which the highest occurrence of swelling disease was reported.

-         Only for the age group weaning to 12 months of age, did supplementation had a significant effect on the occurrence of swelling disease. According to the odds ratio obtained, farms where these kids received supplementary feeding had a  3.40  greater odds of having swelling disease than farms where they did not receive supplementary feed.

-         Supplying additives had a significant effect on the occurrence of swelling disease in all three younger age groups, where kids that received additives, had greater odds of getting swelling disease than kids that did not receive additives.

-         Kraaling strategy had a significant effect on the occurrence of swelling disease on the farm. The odds ratio obtained indicated that farms where goats were kraaled had a 7.72 greater odds of getting swelling disease than farms where goats were not kraaled.

-         The only source of rams that had a significant effect on the occurrence of swelling disease was where producers bred their own breeding sires. The possibility of a genetic link in the whole swelling disease scenario should therefore not be excluded.

·      Data on historical cases have been collected and will be analysed as soon as it has been captured in the required format.

·      The project is running according to schedule.

ACKNOWLEDGEMENTS

The project leader wants to convey her sincere appreciation to the following people for their valuable contribution in the execution of the project:

PUBLICATIONS

SNYMAN, M.A. & SNYMAN, A.E., 2005. The possible role of Ostertagia circumcincta, coccidiosis and dietary protein level in the development of swelling disease in Angora goat kids. J. S. Afr. Vet. Ass., 76(2) : 63-68

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AN INVESTIGATION INTO THE EFFECT OF DIFFERENT WEANING PRACTICES ON THE POST-WEANING GROWTH OF ANGORA KIDS

J.H. Hoon

AIM AND OBJECTIVES

The aim of the project is to find practical solutions for the problems generally associated with post-weaning stress in Angora goats.

The objective of the study is to determine the effect of different weaning methods on:

·                     the post-weaning growth of Angora kids,

·                     the body weight change of ewes from weaning until mating,

·                     the milk production of the ewes and

·                     the conception rate of the ewes in the next breeding season.

BACKGROUND

Weaning is normally a stressful period in the young kids’ life and is often characterized by a decrease in weight gain, total seize in growth and in some cases even weight loss. This response is referred to as weaning shock. The level or degree of shock depends on age and weight of the kids, as well as the feeding program before weaning. From studies with both goats and sheep, it appears that body weight at weaning is normally more important than age when attempting to minimize weaning shock. Other factors influencing the effect of weaning shock on the growth of Angora kids are, amongst others, the general health of the kids, sex and other stress factors.

Weaning shock and its subsequent negative effects, is one of the biggest problems in the Angora goat industry. The weaned kid goes through a very critical growth stage from weaning (4-5 months of age) until it reaches the young goat stage (2-tooth). The artificial, early separation process between mother and kid is very drastic and, therefore, farmers try to wean their kids as late as possible. In practice, however, farmers also want the mating season to start as early as possible since the perception exists that the earlier the kid is born, the healthier and stronger it will be. It means that kids cannot be weaned later than February, because the ewe needs a resting period of at least three to four weeks before the start of the next mating season. Farmers use different practical methods in an effort to limit the large negative effect of weaning shock on the post-weaning growth of the kids.

EXPERIMENTAL PROCEDURES

The project was started on a farm in the Middelburg district during the 2003/2004 kidding season. It was repeated at the same locality during the 2004/2005 kidding season and again during the 2005/2006 kidding season. The farmer’s own animals were used and the animals grazed on natural veld. The nucleus of ewes in each group consisted of ewes that were also used in the 2004/2005 kidding season. At the onset of lambing in September 2005, a flock of Angora ewes and their kids were randomly tagged with three different colour ear tags, namely red, orange and yellow and were also numbered individually.

At weaning (27/02/2006) the three treatments commenced as follow: Treatment 1 (Weaned) – Kids and ewes were separated, i.e. normal weaning took place; Treatment 2 (Swopped) – Kids were separated from their mothers, but were put with other mature ewes, i.e. normal weaning but weaned kids stayed with other ewes; Treatment 3 (Not weaned) – Kids and ewes remained together, i.e. no weaning took place. The on-farm layout was as follows: the ewes and kids of Treatment 3 (Not weaned) were kept with the ewes of Treatment 2 (Swopped); the ewes of Treatment 1 (Weaned) were kept with the kids of Treatment 2 (Swopped); the kids of Treatment 1 (Weaned) were kept separately.

Body weights of ewes were recorded at weaning (27/02/2006) and at the start of the mating period (03/04/2006). The mating season started on 03/04/2006 and ended on 08/05/2006. Body weights of the kids of all three groups were recorded at weaning (27/02/2006) and again at 7-month (03/04/2006), 8-month (11/05/2006), 9-month (13/06/2006) and 10-month age (11/07/2006). The conception and scanning percentages of all the ewes of the three groups were determined on 27/06/2006 by means of ultrasound scanning. The animals stayed in their respective groups from weaning (27/02/2006) until the final body weights of kids were recorded (11/07/2006). All the animals were subjected to the same management practices throughout the experimental period.

RESULTS AND DISCUSSION

The body weights of kids after weaning in 2003/2004 and 2004/2005 in general indicated that the kids that were not weaned (Treatment 3), performed better than the weaned kids (Treatment 1) and the kids that were kept with other mature animals (Treatment 2). The very high rainfall in 2006 contributed to the fact that kids experienced many health problems, including the occurrence of swelling disease, coccidioses, diarrhoea, etc. These negative effects were more profound in the kids grazing in larger flocks together with other mature animals (Treatment 2 and 3), explaining the higher body weights (P<0.05) of the kids that were weaned (Treatment 1).

In both 2003/2004 and 2004/2005, the ewes of Treatment 3 (Not weaned) had the smallest increase in body weight from weaning until the start of the mating period, followed by Treatment 2 (Swopped) and Treatment 1 (Weaned). It would therefore appear that the non-weaning of kids (Treatment 3) had a slightly negative effect on the body weight change of the ewes from weaning until mating. In 2005/2006, however, body weight changes of ewes from weaning of kids until mating differed very little (P>0.05). It is also noteworthy that the average body weights of the ewes at weaning of kids in 2005/2006 were higher than the corresponding weights in 2003/2004 and 2005/2006. This can probably be attributed to the above-average rainfall and subsequent good grazing conditions early in 2006.

In 2003/2004 and 2004/2005 the conception and scanning percentages of the ewes of Treatment 2 (Swopped) and Treatment 3 (Not weaned) were higher than that of Treatment 1, where kids were weaned. It would, therefore, appear that the non-weaning of kids did not have any negative effect on the reproductive rate of the ewes in 2003/2004 and 2004/2005, despite a small negative effect on body weight change from weaning until mating. In 2005/2006, the differences in conception and scanning percentages were relatively small and did not follow the same trend observed in 2003/2004 and 2004/2005.

The hair production of the kids of Treatment 3 (Not weaned) and Treatment 2 (Swopped) at second shearing in 2004/2005 were higher (P<0.05) that that of Treatment 1 (Weaned). These differences in average hair production concurred with differences observed in body weights. The fibre diameter of the kids of Treatment 3 (Not weaned) were also higher (P<0.05) than that of Treatment 1 (Weaned) and Treatment 2 (Swopped), possibly indicating better nutritional conditions.

CONCLUSION

The project procedures were repeated for a third year at the locality in the Middelburg district. The results from the 2004/2005 kidding season concurred to a large extent with the results obtained during the 2003/2004 kidding season with regard to the post-weaning growth of Angora kids, with higher body weights for kids that were not weaned (Treatment 3). This has changed somewhat in the 2005/2006 kidding season, mainly due to the higher incidence of diseases as a result of the abnormally high rainfall. The non-weaning of kids also did not have any negative effect on the conception and scanning percentages of the ewes in the 2003/2004, 2004/2005 and 2005/2006 kidding seasons. The higher conception and scanning percentages observed where kids stayed with ewes (Treatment 2 and 3) in 2003/2004 and 2004/2005, is a phenomenon that possibly needs to be investigated further. The average hair production of kids at the second shearing in 2004/2005 was also influenced positively by the practice of non-weaning, while the average fibre diameter of the fleeces of the non-weaned kids was higher.

A participant was identified in the Jansenville district and the project will start at this locality on 20 August 2006 when the kidding season starts. An effort will again be made to identify two more participants for the project, one from the western and one from the eastern part of the main Angora goat producing areas. The project will be repeated for three kidding seasons at each locality in order to minimize year effects and to obtain sufficient data to make sound recommendations to producers with regard to different weaning practices for Angora goats.

ACKNOWLEDGEMENTS

The following organizations and people supported and were involved in the execution of the project:

Department of Agriculture – GADI

Mohair SA

Mr Jannie Moolman (Rusoord, Middelburg)

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DEVELOPMENT OF SIMULATION MODELS FOR LIVESTOCK ENTERPRISES

M.J. Herselman

AIM AND OBJECTIVES

The aim of the project is to develop computerised models for simulating the biological and economic aspects of livestock enterprises.

The objectives of the project are:

·                To develop a model that describes the change in net economic return of livestock enterprises as a function of a series of physical, biological and economic parameters

·                To use the model as basis for economically sound advice to producers

·                To use the model to quantify economic realities of research findings and new technologies

·                To integrate models for different enterprises with financial data to conduct viability studies for farming businesses

INTRODUCTION

It is often expected from advisors to know all the economic realities of different aspects of small stock farming and its associated management practices. Due to the complexity of calculating these interrelationships, the economic implications of advice given by advisors are in most cases not known. As a result, the Grootfontein Agricultural Development Institute initiated a project in 1987, which would enable the then extension officers of the Department of Agriculture to give more informed advice to extensive sheep producers.  By 1988, several simulation models were released. These initial models were Lotus 1-2-3 spreadsheets. Minor improvements and upgrading over the years kept the models relevant and the SM2000 model, which was released in 2000, was a Microsoft Excel version of the models released in 1988. The SM2000 model has been used extensively in South Africa and is still frequently downloaded from the GADI website from around the world. The SM2000 model has been used frequently to calculate economic aspects of research results for publication in scientific journals. In 2000, the VIAPRO model was also launched as a tool for conducting viability analysis of farming businesses. However, this model could only accommodate one enterprise at a time and it is relatively difficult to use. During 2005, it was decided to upgrade existing models and to incorporate all the different stand-alone models into one model (SM2006) which would allow analysis of individual enterprises to the level of gross margin, but in which the integration of different enterprises with financial information would allow viability analysis of a farming business to the level of cash-flow projection.

PROGRESS TO DATE

Upgrades on the previous model (SM2000) include the following:

·       Inclusion of enterprise modules for wool sheep, mutton sheep, Angora goats, Boer goats, beef cattle and ostriches. Each one of these modules is the equivalent of the old SM2000 model.

·       Selection of enterprise modules through self-explanatory icons from main menu.

·       Each enterprise module now only consists of one screen (worksheet) for input of variables and for display of results.

·       Enterprise modules were made more flexible especially with regard to the mating systems which can be selected.

·       Selection from lists is now made by means of drop-down menus.

·       Animal health cost calculation has been refined in a user-friendly way.

·       Integration of enterprise modules into a farming business viability tool.

·       Projection of product prices and cost factors from historic trends for viability projection.

MODEL LAYOUT

A short description of the different input/output screens is given below.

Main Menu

The main menu page contains icons for selection of the different enterprise modules, as well as selection of the pages for viability analysis, sheep feedlots, farm information, prices of livestock medicine and the database with historic data on product prices. The information of the “Farm”, “Medicine” and “Trends” sheets are used in the enterprise modules and viability projection.

Farm sheet

Certain data required by the enterprise modules and the viability projection are entered in the Farm sheet of the model.

Medicine Sheet

The medicine sheet contains the names and prices of different animal health products. The prices that are currently in the model are fictitious and still needs to be obtained from the suppliers. These products and prices are carried forward to the animal health programs of the different enterprise modules. These prices need to be updated from time to time by the user.

Trends Sheet

This is an all new addition to the previous models developed by GADI. The information and results calculated from it are used in the sheet for projection of viability of the farm business, which replaced the old VIAPRO model. Historic prices of different items are typed into the table and year-on-year factors are then estimated by means of regression methods. For each one of these, the number of years on which the year-on-year values should be based, is selected from a drop-down menu. The data in the table are only updated once a year as time progresses. This sheet is still under development with the trends for producer price, feed price, animal health product price, packaging material price and fuel price still missing.

Enterprise modules

The basic layout of the different enterprise modules is the same. The left half of the screen is for input of data while the output is displayed on the right half of the screen. The most significant addition is the inclusion of more mating systems. The so-called “halfpaarstelsel”, contemplated as an accelerated mating system whereby the flock is divided into two groups and mated every eight months but one group lagging the other by 4 months, has also been incorporated as an option. Selection from lists is now made by means of drop-down menus. The analysis of an enterprise is done to the level of gross margin. This value is then carried forward to the viability projection sheet. To the left of the title of the page are different buttons that can be selected. The “Back” button will take the user back to the main menu. The “Recalc” button should only be clicked when prompted to do so. The “Health” button will take the user to the screen where the animal health program of the specific enterprise module is entered. The “Defaults” button will take the user to a sheet where certain variables that are normally kept constant, can be changed if required. The “Print” button will automatically print the page but without the background colours.

The health program of each enterprise is entered into its own Health sheet. Each line in the table is for entry of a unique animal health treatment. The “Description” column is for user notes, while the “Product” column is selected from a list. The information comes from the Medicine sheet. The “Animal” column is also selected from a list.  In the “ml” column, the dose size of the specific treatment is entered while the number of treatments per year for the specific animal class is entered in. The “Cost” is calculated by linking the information in each line with the number of animals in that specific animal class, as calculated from the information entered into the enterprise module. The animal health sheet, together with the medicine sheet, is a new addition to the previous model (SM2000) and is viewed as a large improvement with regard to user-friendliness.

Viability projection

The viability sheet is the replacement for the previous VIAPRO model. This sheet combines the outputs of the enterprise modules and certain information from the “Farm” and “Trends” sheets, as well as other financial information that is entered into this sheet by the user. For user assistance, comments (red markers) have been inserted to many cells. When the cursor is moved over such a marker, help will be displayed automatically. The projection is made over a 20-year period. This sheet is viewed as a huge improvement on the previous VIAPRO model.

SUMMARY

Certain parts of the model are still under development and will be completed before the end of 2006. These include the regression analyses required for estimation of the year-on-year increases in production price index and of different input cost factors. The help page is also under construction and will only be finalized after all the other pages have been finalized. More comments will also be inserted in the different pages to assist the user when entering data. After finalization of the model, the first version will be extensively tested before it will be posted on the GADI website.

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ESTABLISHMENT OF RAM BREEDING FLOCKS FOR DIFFERENT COMMUNAL FARMING AREAS OF THE EASTERN CAPE

B.R. King

AIM AND OBJECTIVES

The aim of this project is to establish ram breeding flocks for different communal farming areas.

The objectives of the project are:

·      Improvement of woolled sheep flocks of rural communal farmers

·      Establishment of a group-breeding nucleus in each community

·      Community group-breeding flocks supply rams to neighbouring communities in the long term.

INTRODUCTION

This project forms part of the larger program for woolled sheep development in the communal areas of the Eastern Cape. This project started in August 2002 with the identification of 16 communities by the committee members of regions 20 to 24 of the NWGA, which represent the former Transkei and Ciskei areas. The layout of the woolled sheep development program consists of:

·       The annual supply of 3000 rams to communal farmers – managed by the NWGA

·       The evaluation of the impact of the rams that were introduced through progeny testing – performed by GADI

·       The establishment of 16 ram breeding groups in the communal areas, which will eventually supply rams to neighbouring communities – managed by GADI.

This specific report deals with the latter of the abovementioned aspects. The 16 communities, as well as their geographical location, are illustrated in Table 1 and Figure 1.

Table 1. The 16 communities in the Eastern Cape

Figure 1. The 16 communities in the Eastern Cape

RESULTS AND DISCUSSION

At a strategic planning session held with the different role-players, it was decided that some of the communities would be withdrawn from the project. The main reason was that these communities would never be able to breed good quality rams due to the fact that the sheep produce low quantities and below average quality wool. Lack of commitment to the project was another big factor in these communities. Roxeni community, situated near Alice, is a community where their sheep numbers were to small to conduct a ram breeding project. It was decided that all these communities would still get rams from the larger project, which is managed by the NWGA.

CONCLUDING REMARKS

·       Good progress was made with eight communities and these communities will receive more attention in future.

·       At least three communities should be able to breed their own rams and the evaluation of rams will start early next year.

·       One of the biggest problems experienced is sheep scab, which increased especially in the surrounding communities and causes a decrease in wool production.  

ACKNOWLEDGEMENTS

The following organizations supported / participated in the project:

Eastern Cape Department of Agriculture

National Wool Growers’ Association

Participating communities

Agricultural Research Council: Livestock Business Division - Animal Production.

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EVALUATION OF THE GENETIC POTENTIAL FOR GROWTH AND WOOL PRODUCTION OF TYPICAL TRANSKEI EWES AND RAMS

P.G. Marais

AIM AND OBJECTIVES

To determine the impact of the NWGA livestock improvement project in the communal areas of the Eastern Cape.

The objectives of this study are:

·      To evaluate the commercial rams bred for the NWGA project vs the communal rams in the communal areas of the Eastern Cape through  progeny tests

·      To evaluate the communal rams vs the commercial rams in the commercial areas of the Eastern Cape through progeny tests.

INTRODUCTION

This project forms part of a larger livestock improvement project for woolled sheep development in the communal areas of the Eastern Cape. The larger project of the NWGA includes a program whereby 3000 commercially bred rams are annually supplied to the communal farmers in the Eastern Cape. The aim of this project is to evaluate the impact of these rams supplied by the NWGA ram breeding project to increase the production potential of the wool sheep in the communal areas. This project was done in two phases, namely, 1) evaluating the progeny from communal and commercial bred rams under commercial conditions and 2) to evaluate the progeny of these rams under communal conditions. Results from the first phase were presented in the previous report. Therefore, only the results from the evaluation under communal conditions are discussed in this report.

To establish the communal part of the project, four communal areas were selected on the basis that they must represent the average farming conditions of the Transkei region. The four participating communities were Ncorga Inagatu Irrigation Scheme (Umgababa community, Engcobo), Quatsa New Mines Community (Mbheku shearing shed, Tsomo), Sokapasa Community (Ngqamakhwe) and Singinquni Community (Kentani). A number of ewes were randomly chosen at each community, divided in two groups and each group was individually tagged and numbered with different colour eartags. One group of ewes was designated to be mated to six rams which originated from commercial farmers. The other group of ewes was put to six typical Transkei rams. During the week of 11 – 14 October 2004 the identified ewes were synchronized with sponges (See number of ewes at each community in Table 1). During the week of 25 – 28 October 2004 rams were put to the ewes in the specific groups. Each group of ewes was mated by the designated ram group for 35 days. Hired shepherds were responsible to keep the groups separately for the mating period. After the mating period the ewes were allowed to return to their respective owners. The ewes started lambing on the 15^th March 2005. Tagging of lambs was done at each community on a weekly basis. During the week of 6 – 9 June 2005 the tagging, dosing of lambs and ewes as well as the castrating of ram lambs, were done. The following data were collected from all four communal farms: number of ewes mated, number of ewes lambed, number of lambs born, sex and body weight at weaning, 7 and 14 month of age.

RESULTS AND DISCUSSION

The number of ewes mated in each group at the different localities, together with the number of offspring available for weighing at the different ages, is shown in Table 1. The large variation obtained in reproduction among localities and groups cannot be explained, but could possibly be the result of differences in grazing conditions and the acclimatisation of commercial versus Trankei rams to the environmental conditions. Furthermore, the fact that some of the commercial rams were bred in non heartwater areas for the ram breeding project and moved to communal areas with a high incidence of heartwater, could also have contributed to the low reproduction rate observed among the commercial groups. Nonetheless, the aim of the project was not to evaluate the reproduction obtained in this part of the study, but to evaluate the production of the offspring born from mating commercial rams to communal ewes.  The average weaning weight, 7-month weight and 14-month weight of lambs in the different mating groups and communities are illustrated in Table 2.

Table 1. Reproduction data of ewes mated with commercial and Transkei rams at the different communities.

*Tran = Transkei                  **Com = commercial

Table 2 Average body weight of lambs from ewes mated with Transkei and commercial rams at different communities (kg± SE)

No significant differences in the weaning weight, 7-month weight and 14-month weight between the offspring of the two mating groups could be detected. The differences at weaning between the offspring of commercial and communal rams were 0.5 kg, at 7 months of age 1.2 kg and at 14 months of age 0.8 kg.

CONCLUSION

From the reproduction data collected from the four communities it is evident that low to very low reproduction results were reported. It is noteworthy that the weight advantage of lambs from the commercial versus communal rams was very small between weaning weight, 7 months of age and 14 months of age. These results demonstrated that by introducing commercial rams to communities in the Transkei, a small improvement in growth is possible. The impact of commercial rams on wool production and wool quality in the communal areas will be recorded during the next reporting period.

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DETERMINING THE OPTIMUM GRAZING CAPACITY IN THE EASTERN MIXED KAROO

T.P. Nengwenani

AIM AND OBJECTIVES

The aim of this project is to determine the optimum stocking rate for the Eastern Mixed Karoo veld.

The objectives of the study are:

·     To stock veld at different rates with different small stock types

·     To monitor impact on veld condition

·     To monitor the production of livestock at different stocking rates

·     To determine the optimum grazing capacity.

BACKGROUND

During the 1970’s to mid 1980’s it became evident that much uncertainty existed amongst pasture researchers and the farming community about the stocking rates that can be applied in different veld types.  The grazing capacity strategy was launched by the then Minister of Agriculture, Mr Sarel Hayward, but the Department was severely criticised by the farming community when the first grazing capacity map for South Africa was released during early 1981. This necessitated drastic measures to be undertaken and the so-called stocking rate trials came into being all over South Africa in all the provinces. One trial was initiated at Grootfontein, known as the Hereford/Afrikaner stocking rate trial.  Angora goats and Merino and Dorper sheep were stocked at three stocking rates.  The middle-stocking rate was at the recommended grazing capacity, one stocking rate was slightly higher and one was slightly lower.

Almost from the start the Angora goats did not produce well.  However, good production was obtained from the Merinos and Dorpers.  These animals grazed in a two paddock system with a period of grazing of four months, one of the systems that farmers were advised to follow.  However, the middle stocking rate of the Merino sheep, which were stocked at the grazing capacity norm, was duplicated. In this system the paddock for the four months were sub-divided into four even sized paddocks and the sheep are moved between paddocks on a two-weekly basis.

This experiment is being carried out on two blocks of veld at Grootfontein known as Afrikaner camp and Hereford camp.  The grazing period of four months results in the staggering of the grazing period, so that no paddock is grazed at the same time for two years running.

RESULTS AND DISCUSSION

The mass gained by animals in 2005/2006 for 238 day are presented in Table 1 and 2.

Table 1. The mass gained by the Merino sheep in the different treatments