ABSTRACT
Several studies have investigated the relationship between heterozygosity, genetic distance and production traits. The objective of the present study was to evaluate the influence of the degree of heterozygosity and genetic distance on growth, carcass and reproductive related features in F1 bovine crosses. We tested 10 polymorphic markers in 330 purebred cattle (Nelore, Canchim, Aberdeen Angus and Simental) and 256 crossbred cattle belonging to four crossbred groups. Individual heterozygosities (Hi) and multilocus genetic similarity (Dm) were estimated and used in correlation analysis against individual phenotypic measurements. Significant (p < 0.05) Hi effects occurred for birth weight, 15 to 18 month weight, hot carcass weight and longissimus rib eye area. The extent to which increased heterozygosity (deltaH) in F1 crosses can be predicted from the genetic distance of parental breeds was also investigated using Nei's standard genetic distance (Ds) and standard heterozygosity (Hs). High correlations were found between deltaHi, deltaHs and the Ds of the parental breeds. Our results suggest that heterozygosity of the ten molecular markers used in this study may affect live weight during at least one growth phase. Parental genetic distance was a suitable predictor of the degree of progeny heterozygosity.
Subject(s)
Animals , Cattle/genetics , Crosses, Genetic , Heterozygote , Food Production , Polymorphism, GeneticABSTRACT
Aberdeen Angus beef cattle from the Brazilian herd were studied genetically using restriction fragment length polymorphism (RFLP) of the kappa-casein - HinfI (CSN3 - HinfI), beta-lactoglobulin - HaeIII (LGB - HaeIII) and growth hormone AluI (GH- AluI) genes, as well as four microsatellites (TEXAN15, CSFM50, BM1224 and BM7160). The RFLP genotypes were determined using the polymerase chain reaction (PCR) followed by digestion with restriction endonucleases and electrophoresis in agarose gels. With the exception of the microsatellite BM7160, which was analyzed in an automatic sequencer, the PCR products were genotyped by silver staining. The allele and genotype frequencies, heterozygosities and gene diversity were estimated. The values for these parameters of variability were comparable to other cattle breeds. The genetic relationship of the Aberdeen Angus to other breeds (Caracu, Canchim, Charolais, Guzerath, Gyr, Nelore, Santa Gertrudis and Simmental) was investigated using Nei's genetic distance. Cluster analysis placed the Aberdeen Angus in an isolated group in the Bos taurus breeds branch. This fact is in agreement with the geographic origin of this breed