Additive genetic, dominance and recombination effects in breedings among Santa Inês (SI), Brazilian Somali (So), Dorper (Do) and Poll Dorset (Po) breeds were estimated for growth, reproductive and maternal hability traits. Data were obtained from Gaasa e Alimentos LTDA, a company that participates on the Programa de Melhoramento Genético de Caprinos e Ovinos (GENECOC) coordinated by Embrapa Caprinos. Initially, 3,573 records were analyzed using the MIXED procedure of the statistical package SAS (1999). The analyses were carried out considering the effects of additive genetic difference among breeds, dominance and recombination effects. Birth weight was mainly influenced by additive genetic effects, while weaning weight and pre-weaning weight gain were influenced by non-additive genetic effects. Direct heritability estimates for birth weight was moderate indicating that there is genetic variability believable to be exploited by individual selection. In the same way, heritability estimates for the traits age at first lambing and litter total weight at birth indicated the existence of genetic variability to obtain genetic gains through selection. Genes of the Poll Dorset and Dorper breeds had an important role for a better growth performance, therefore, these breeds can be indicated as sires in the terminal breeds. The use of F1 Santa Inês x Brazilian Somali females on crossbreeding with Poll Dorset rams can lead to a better reproductive efficiency.
crossbreeding; epistatic effects; heterosis; productive performance
