Genetic analysis of milk production traits in Jamunapari goats

Data on 2612 lactations from 990 does kidding from 1993 to 2010 at the Central Institute for Research on Goats, Makhdoom (Uttar Pradesh) were analyzed for milk yield (MY) at 90 days, 140 days, total lactation milk yield (TMY) and lactation length. The corresponding least squares means were 78.30±0.68, 111.42±1.50, 117.19±1.24 litres and 156.37±1.21 days, respectively. Period of kidding, parity and weight of dam at kidding affected the lactation traits significantly (P<0.01). Seasons of kidding and type of kidding were also (P<0.05) significant sources of variation for 90 and 140 days milk yields. Lactation length was affected by season of kidding only. Goats kidding during spring yielded more (P<0.05) milk at 90 days whereas higher (P<0.05) lactation length was observed in autumn kidders. Goats which delivered multiple births produced more milk (P<0.05) than those delivered single birth. Goats with higher body weight at kidding (P<0.05) produced more milk. The genetic correlations among milk production traits were high and ranged from 0.451±0.557 (90d-MY and 140d-MY) to 0.866±0.128 (90d-MY and TMY). The estimates of h² for lactation traits were low. Small population size, low voluntary culling of females and lower intensity of selection for lactation traits might be the probable reasons for low genetic variability and inconsistent milk production performance in this flock.