Effects of controlled seasonal breeding on reproductive performance traits of pastoral goat herds in northern Kenya

A systematic breeding programme in a herd of Small East African goats was initiated in Isiolo District, northern Kenya. The study was undertaken to assess the effect of controlled seasonal breeding on the biological productivity of pastoral goat flocks. This paper reports the results of statistical analyses of reproductive performance traits (conception, abortion, birth, prolificacy, fecundity and weaning rates) measured for six mating seasons of 2 months duration each. It is shown that environmental seasonality as it prevails throughout northern Kenya significantly impacts individual reproductive traits in goats. The most pronounced influence was detected in relation to prolificacy and fecundity rates. However, the experimental mating season treatment could not be shown to have a statistically significant influence on reproductive traits. It is concluded that inter-year variability in seasonal environmental conditions were too high to permit a clear expression of statistical differences between the six mating seasons with respect to the traits considered. Nevertheless, it appears that joining does just before the onset of the long rains could produce the largest number of offspring per doe exposed. However, estimated weaning rates indicated that this superiority is entirely lost due to high mortality of young kids during the long dry season following thereafter. Controlled seasonal breeding, therefore, is most likely to be an inefficient management tool to improve reproductive performance of pastoral goat herds. (C) 2003 Elsevier Ltd. All rights reserved.