The influence of non-genetic factors on the shape of lactation curves in Red Sokoto goats

Abstract

AbstractMilk yields of 66 nursing does recorded in Zaria, Nigeria were used to characterize the lactation curve and study the influencing factors in Red Sokoto goats. Lactation curve parameters obtained by fitting the model: Yt = atbe –ct were subjected to statistical analysis, using herd, season, parity, litter size and litter composition of dams.The results indicate that the lactation curve of these goats was characterized by milk production increasing in early lactation, attaining a peak at approximately 2 to 5 weeks post partum and thereafter declining slowly to the end of lactation. The observed total yield, peak yield, peak day and the estimated persistency defined as c–( b + 1) was 79·3 kg, 1·2 kg, 20·5 and 143·2, respectively. Parameters ‘ a‘ and ‘ c‘ were strongly but negatively correlated ( r = –0·53; P < 0·01). The curve parameters ‘ a‘ and ‘ c‘ differed by herd and season ( P < 0·05); and parity only affected ( P < 0·01) parameter ‘ a‘. None of the factors significantly influenced parameter ‘ b‘ ( P > 0·05).The significant herd and season effects may have practical implications in determining optimal feeding management and season of breeding to maximize total lactation yield.