Genetic evaluation of Marwari sheep in arid zone: growth.

The data of Marwari lambs were analysed to study the effect of various factors on body weights. The overall least squares means were 2.77 ± 0.04, 11.78 ± 0.20, 16.45 ± 0.27, 18.74 ± 0.33 and 20.70 ± 0.31 kg, respectively for body weights at birth, 3, 6, 9 and 12 months of age. The year and season of birth significantly affected the body weights at all the ages except the effect of season of birth on 3 and 6 months body weights. The effect of sex and dam's weight at lambing on all the growth traits was also observed to be significant. The lambs born during spring months and the male lambs weighed heavier at all the ages. It was also observed that heavier dams at lambing gave birth to heavier lambs. The estimates of heritability for body weights at birth, 3, 6, 9 and 12 months of age were 0.117 ± 0.099, 0.169 ± 0.105, 0.084 ± 0.095, 0.129 ± 0.100 and 0.083 ± 0.095, respectively. All the genetic and phenotypic correlations were positive except the genetic correlation of birth weight with 9 and 12 months body weights. It was observed that a greater portion of variation in body weights was because of the environmental factors, however, the genetic correlation suggested that selection may be practiced on the basis of 3 or 6 months body weights to improve the subsequent body weights both on genetic as well as phenotypic scale.