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

Milk yields of 66 nursing does recorded in Zaria, Nigeria were used to char acterize the lactation curve and study the influencing factors in Red Sokot o gents. Lactation curve parameters obtained by fitting the model: Yt = at( b)e(-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 increas ing in early lactation, attaining a peak at approximately 2 to 5 weeks post partum and thereafter declining slowly to the end of lactation. The observ ed 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); a nd parity only affected (P < 0.01) parameter 'a'. None of the factors signi ficantly influenced parameter 'b' (P > 0.05). The significant herd and seas on effects may have practical implications in determining optimal feeding m anagement and season of breeding to maximize total lactation yield.