Last update: November 26, 2010 10:25:49 AM E-mail Print


Supplementing protein. Is It economical?


Grootfontein ADI, Middelburg (EC)



In small stock farming, profitability is to a very large extent determined by ewe productivity. Ewe productivity has several components of which the most important are total mass of lamb produced, slaughter mass of culls and, in the case of Angora goats, also the production and quality (especially fibre diameter) of the mohair. The high price premium which kid and young goat hair receives, emphasizes the importance of increasing the number of kids in the flock in order to increase ewe productivity and, hence, profitability. Weaning percentages can be increased by increasing pregnancy percentages and multiple births, but the best option would probably be to decrease kid mortalities. Many kids die in the period just prior to birth up till approximately seven days after birth. Research has shown that up to 80 percent of these mortalities are associated with the ewe's nutrition during the last few weeks before kidding and the first few weeks after kidding. The quantity of colostrum available at kidding and milk production after kidding are the factors which play the most important part in kid survival as well as growth rate of kids.

The supply of sufficient protein during late pregnancy and lactation is important because it has an influence on both the quantity and quality of the milk produced. According to certain research results, it would seem as if the supply of a high level of bypass protein (non-degradable protein) is essential to increase the production of colostrum and milk in ewes.

Various role-players in the Angora goat industry expressed a need for an investigation into the economic advantage of supplementing various sources of protein in the veld during late pregnancy and lactation. For this reason an investigation is being conducted in the most important Angora goat areas which are also representative of the different types of veld. The purpose of this investigation is, therefore, to determine whether the effect of supplementing Angora goats, with various sources of protein, on production and reproduction has any economic advantages for the farmer.

This project is being carried out on a multi-disciplinary basis and a number of participants are involved. Officials of the National Department of Agriculture (Grootfontein ADI) are responsible for this project. The field officers of Cape Mohair & Wool (CMW) were responsible for identifying farmers who are prepared to participate in this project and they also act as co-ordinators in their respective service areas. Mohair South Africa is contributing financially towards the project.

The project is being conducted in the Cradock, Graaff-Reinet, Jansenville and Willowmore districts, which are representative of the different veld types, with one farmer in each district participating.


Experimental procedure

A flock of ewes (approximately 200 to 300 animals) of each participant is divided into three equal groups. Each group is marked with a different colour ear-tag and all the animals are also numbered. They are all weighed at mating and then ultrasonically scanned approximately 42 to 49 days after mating is completed. Those that are not pregnant are removed from the flock.

The ewes run together as one flock at all times. Four weeks prior to kidding they are separated into their respective groups and put into three different camps. One of the treatment groups receives a supplement with a high percentage of bypass protein, the other group a supplement with a low percentage bypass protein (Urea), while the control group receives no supplementation at all. The nutritional value of both supplements, in terms of protein and energy, is exactly the same. The only difference is the type of protein which is included (high vs low) degradability) in the supplement.

Supplementation is given at 300g/ animal/ day prior to kidding and 400g/ animal/day after kidding. The various camps which are used are relatively homogeneous in respect of the quantity and quality of plant material and the size of the camps are also approximately the same. The number of kids born are duly recorded in order to monitor kidding percentages, kid mortalities, etc, and to determine the average age of the kids. Depending on management, the kids are tagged with the same colour and number ear-tags as their mothers either during or at the end of kidding. Supplementation is maintained until eight weeks after the first ewe has kidded, which means a total feeding period of 12 weeks. When supplementation is discontinued, the ewes and kids of all three groups are run together again as one flock until weaning time.

The following data is collected:

* mating mass of ewes and mass of ewes when the kids are 42 days of age,

* the 42-day mass and weaning mass of kids,

* percentage pregnancies (at scanning),

* kidding percentage,

* weaning percentage,

* kid mortalities, and

* the fleece mass of individual animals will also be determined once.

The rainfall is also continuously monitored and an evaluation of the veld (quality and quantity) in each locality is done once. This information will be utilized in conjunction with the results to make more accurate deductions and conclusions. All aspects of management at each1ocality, during the duration of this investigation (animal health programmes, etc), are also recorded by the participants.

In order to reduce the effect of certain annual variations, the project with the four participants will continue for at least three kidding seasons. At the next kidding season the ewes will again be divided into the same groups. Old ewes and ewes with faults will be culled and young ewes (replacement ewes) will be divided equally among the three groups to make up the numbers again.


Present status of the investigation

The investigation commenced during the preceding kidding season (2000). Four participants were identified in the respective districts by field officers of CMW. At each participant a flock of 200 to 300 Angora goat ewes were divided into three equal groups. Supplementation in the four localities commenced in August 2000 (prior to kidding) after the ewes were placed in three different camps within their respective groups. Supplementation was terminated eight weeks after the ewes had started to kid and the 42-day mass of both kids and ewes were taken. The ewes and kids of the three groups were then run together as one flock until weaning time when the mass of the kids were again taken. Kidding and weaning percentages as well as kid mortalities were monitored.

Veld conditions were very good in all four localities during the mating season (March and April 2000). At two localities (Graaff-Reinet and Cradock) good rains fell during September and October 2000, the time when supplementation was given. This resulted in problems to maintain the recommended intake at these two localities. The results in Table 1 show the provisional results in respect of body mass which were obtained during the first year.

From this information it seems as if there were relatively small differences in respect of both ewe and kid mass between the control group and area group during the 2000 kidding season. However, the bypass group showed better mass gains.

As regards kidding and weaning percentages, and kid mortalities, there were no differences between the three groups.

It should be kept in mind, however, that this project is still in its infant stage and that insufficient data is available to be able to make meaningful deductions. Furthermore, it is also important to take into consideration that body mass, as such, does not make a very big contribution to the economy of Angora goat farming. The difference in reproduction performance of ewes and the survival rate of kids will be the most important criteria to influence the economy of the different supplementations.

These factors will be duly monitored during the present year (2001) in order to establish what the possible carry-over effects, of the treatment which the ewes received in 2000, will be on the same ewes during the 2001 kidding season.