Abstract:
The data on 1227 kids belonging to Malabari (309) Saanen x Malabari (389) and Alpine x Malabari (309) genetic groups born and brought up at the All India co – ordinated Research Project on Coats, Kerala Agricultural University, Mannuthy during the period from April 1974 to March 1979 were utilised to study the effects of various genetic and non genetic factors on body weight at different ages.
Crossbred goats, S x M and A X M, registered higher weights at birth, at one month, at four months and at one year than the local Malabari goats. District sexual dimorphism in body weights at different ages could be observed in crossbred goats. Litter size significantly affected birth weight and weight at one month. Sason of birth had only non significant influence on weights at birth and that at one month, though the effect was significant on 4 month’s and one year weights. Even though the effect of gestation length undergone by kids was a significant source of variation for weights at birth alone in Saanen x Malabari and Alpine x Malabari kids, the same had significant effect on body weights at birth and at one month in Malabari. Significant effects of dam’s weight at kidding on weights at birth, one month and four months in Malabari ; at birth and a one month in Alpine x Malabari and at birth alone in Saanen x Malabari could be observed. Sire effect was significant on body weights at one month, 4 months and one year in Malabari, at birth and one year in Alpine x Malabari and one year alone in Saanen x Malabari. The growth rate was found to be highest in A x M upto four months of age and afterwards upto one year S X M showed highest rate of gain. The effect of genetic group on growth rate was found to be significant during all the periods of growth.
The heritability estimate for weight at birth was near to zero. The h2 estimates were seen getting higher as the age advanced. Genetic correlations between body weights at different ages were found to be fairly high. But the phenotypic correlations between weight at different ages were found to be highly variable. Twins were more than singles in all the genetic groups and the secondary sex ratio was found to be 50:50.
The results of the study indicated that crossbreeding of local goats with exotic breeds, Saanen and Alpine, is the desirable breeding plan to accomplish the improvement of body weight in goats, at different ages.
