Effect of non-genetic factors on body weights in Malpura sheep

Recorded data on body weights at birth, 3, 6, 9 and 12 months of age of Malpura sheep, over a period of 45 years (1975 to 2019) at ICAR-Central Sheep and Wool Research Institute, Avikanagar (Rajasthan) were used to study the effect of non-genetic factors on body weights. The overall least-squares mean for body weights at birth, 3, 6, 9 and 12 months of age were 3.06±0.01, 14.50±0.05, 21.92±0.08, 25.02±0.09 and 28.11±0.10 kg, respectively. Period of birth, season of birth, sex of lambs and parity of dam had significant (P<0.01) effect on body weights. An increasing trend in body weights was observed with increase in parity up to 3^rd parity. Lambs born in autumn achieved higher body weights at all the stages than lambs born in spring season. Males were heavier than females at all the stages and the sex differences were increased with age. Regression of dam's weight at lambing was a significant (P<0.01) source of variation for pre-and post-weaning body weights. The significant effect of non-genetic factors on growth warrants inclusion of these factors in mixed models used for genetic evaluation andestimationof breeding values.