Crossbreeding of imported and native goats in a dry tropical environment. I. Survival and growth of kids

Three contemporary groups were formed for a mixed model analysis of body weights (kg) at successive ages of 1468 kids born between 1969 and 1978 in a crossbreeding experiment conducted at Loma de Leon Field Station in Venezuela. Group I (1969-1974) included: ¢ Nubian ¢ Native, ¢ Alpine ¢ Native, ¢ Toggenburg ¢ Native, 3/4 Nubian + Native, and 3/4 Alpine + Native. Group II (1971-1978): 3/4 Nubian + Native, and 7/8 Nubian 1/8 Native. Group III (1975-1978): ¢ Alpine + Nubian, + Native ¢ Nubian, + Alpine + Native, and ¢ Nubian + Toggenburg + Native. Birth, weaning (4 mo.), 6 month weights, and first year mortality rate for above breed groups were: Group I: 3.2, 11.3, 15.2, 26.5 percent; 3.4, 11.8, 17.0, 42.4 percent; 2.9, 11.8, 15.9, 39.9 percent; 3.1, 12.1, 15.3, 40 percent; and 3.4, 14.7, 18.1, 46.3 percent. Group II: 3.1, 11.8, 14.2, 40 percent; and 3.1, 11.9, 14.3, 41.3 percent. Group III: 3.2, 11.8, 14.8, 47.5 percent; 3.2, 12.6, 14.6, 38.3 percent; and 2.9, 11.5, 14.0, 37.0 percent, respectively. Phenotypic correlations between weights at birth and weaning, birth and 6 months, and weaning and 6 months were: Group I: 0.29, 0.30, 0.80; Group II: 0.24, 0.27, 0.75; and Group III: 0.28, 0.27, 0.84. All correlations were highly significant. Heritability for birth, weaning, and 6 month weights, calculated by intrasire correlation for the pooled data were: 0.15, 0.08, and 0.22. Repeatabilities were: 0.62, 0.64 and 0.49, respectively. Total litter weights at birth and weaning for the 3 groups were: 5.7, 15.1, 5.4, 14.7; and 5.6, 13.8. Repeatabilities were: 0.26, 0.036; 0.22, 0.053; and 0.16, 0.13, respectively. Significant positive relationships were found between litter weight at birth and postkidding weight of dams