Central Sheep and Wool Research Institute, Avikanagar-304 501, Rajasthan
Least-squares analysis of the body wights and greasy fleece weight records of 556 Bharat Merino lambs, sired by 85 sires and extending over a period of 10 years (1982–92) constants. It revealed that the random effect of sires and fixed effect of periods were significant (p<0.05) sources of variation on all the traits. The effect of sex was significant on all the traits, except GFW2 and GFW3. The type of birth was not significant on any trait, except the weaning weight. The population means for body weights at weaning, six and twelve months of age were 16.65±0.21, 23.44±0.38 and 31.47±0.46 kgs, and those for first six-monthly, second six-monthly and third six-monthly greasy fleece wights were 0.86±0.03, 1.09±0.03 and 1.17±0.03 kgs respectively. The estimates of heritability, and genetic, phenotypic and environmental correlations were computed by the half-sib correlation method after adjusting the data for factors with significant effects. The heritability of body weights at 3, 6, and 12 months were 0.25±0.13, 0.58±0.16, 0.57±0.16 and for GFWl, GFW2 and GFW3 were 0.52±0.15, 0.18±0.13, and 0.38±0.14 respectively. The genetic, phenotypic and environmental correlations among body weights were positive, high and ranged from 0.62 to 0.90. Except for the low estimates of heritability of GFW2, rest of the estimates varied from fairly high to very high indicating that selection for any of the traits should prove effective in bringing about the genetic improvement in these traits. The results tend to conclude that for early selection body weight at six month of age which has high h} and bears positive correlation with GFW, should prove effective in bringing about genetic improvment.
