Genetic Analysis of Growth Rates of Nellore Brown Sheep

The data on body weights at birth, 3, 6, 9 and 12 months of age recorded on 519 Nellore Brown lambs born during 2009 to 2013 maintained at Livestock Research Station, Mamnoor, Warangal district which is a constituent of Sri P.V. Narsimha Rao Telangana Veterinary University, Hyderabad, were utilized for the present study. The overall least squares means for average daily gains during 0-3(ADG1), 3-6(ADG2), 6-9(ADG3) and 9-12(ADG4) months of ages were 109.90±0.28, 84.80±0.23, 45.53 ± 0.20 and 31.29 ± 0.25 g, respectively. The growth rate decreased as the age advanced and was the lowest during 9-12 months. They ear of birth had highly significant (P≤0.01) effect on the average daily gains at 0-3 and 9-12 months of age. The effect of season of birth was non-significant (P≤0.05) on the average daily gains at all ages studied. Males recorded significantly (P≤0.01) higher average daily gains than the females at all ages studied. The estimates of heritabilities of ADGs ranged from 0.02±0.06 to 0.20±0.11.The estimates of heritabilities for ADGs indicated that non genetic factors play an important role and better feeding and management can help to improve these traits.