Adjustment for non-genetic effects on body weight and size in Angora goats

Data on 864 Angora goats, collected from 1988 to 2000, were used to study non-genetic effects on body weight and daily gain from birth to 24 months of age and body size at different ages. Non-genetic factors included birth year, birth month, sex, age of kids, age of dam, type of birth and rearing. Birth year, sex and type of birth and rearing were the major factors affecting growth of Angora goats. Age of dam influenced body weights at birth and weaning, early growth rate and height at withers. The unfavorable effects of young dams on their kids suggested that it was essential to strengthen the feeding and management of kids, especially in maintaining the body weight during mating and pregnancy. Growth rate of kids born from November to February was relatively slower during sucking period but more rapid after weaning than those born between March and July. This can result from seasonal change and suggests that it is necessary to plan the kidding season rationally by controlling the estrus and mating time. The kids born as twin had lower birth weight and slower early growth rate than those born as single, but had a higher post-weaning growth rate. The general trend was the differences between singles and twins decreased as the kids became older, possibly due to a decreasing maternal effect and a growth compensation of twin kids. Additive and multiplicative adjustment factors for body weights and growth rates were derived from least squares means of subclasses for birth month, sex, age of dam, type of birth and rearing. Subclass variances were tested for heterogeneity with Levene's test. The results were used to determine appropriate adjustment for non-genetic effects.