Last update: November 23, 2010 03:51:52 PM E-mail Print


An evaluation of production and reproduction of Boer goats

 II. Age specific replacement and net reproduction rate


P. G. Marais, J.C. Scheltema*


Grootfontein Agricultural College, Private Bag X529, Middelburg, 5900 Eastern Cape,  South Africa

 * P O Box 34253, Newton Park, Port Elizabeth, 6055, Eastern Cape, South Africa


Data from 1985 does and 3336 kids from a commercial Boer goat flock during the period 1978 to 1989 were used to investigate the age specific replacement and net reproduction rate as well as the intrinsic rate of the population increase. It is evident that out of 1000 does entering the flock at 1.5 years of age 351 would be alive for joining at 7.5 years of age and 301 at lambing at eight years of age. The number of does needed for replacement, to keep the flock size constant, decreased from 100% for 2 year old does to 25.5% for 7 year old does. The net reproduction rate increased from 0.48 to for 2 year old does to 2.33 for 8 year old does. The increase of the intrinsic rate reached unity at 4 years of age. It is evident that the reproduction rate of Boer goat does culminate at 4 years of age after which it stabilises. At the present reproduction rate, the Adelaide Boer goat flock cab be maintained with 3 doe age groups (doe age of 4 years).