Environmental and genetic causes of variation in production traits of Damascus goats. 2. Goat productivity

Abstract

ABSTRACTData on 1474 lactation records obtained from 1972 to 1978 were used to study environmental and genetic influences on production characters in the Damascus goat. Year and month of kidding had a significant effect on 90- and 150-day milk production after weaning, lactation length and litter weight at weaning (P < 0·01), but no influence on litter weight at birth. Milk production after weaning was not related to litter weight at birth or at weaning. Age of goat at kidding had a significant quadratic effect on milk production, and litter weight at birth and at weaning. No such effects were found for lactation length.Estimates of heritability, from paternal half-sib correlations, for 90- and 150-day milk production were similar (0·29 (s.e. 0·14)). The genetic correlation between 90- and 150-day milk yield (0·92 (s.e. 0·03)) was high, indicating that part and whole lactation yields are influenced by the same genes. The phenotypic correlations among milk yield traits and lactation length were also high and positive.