Efeito da origem e da linhagem do DNA mitocondrial sobre características produtivas e reprodutivas de bovinos leiteiros da raça Gir

Abstract

The objective of this study was evaluate the mitochondrial DNA influence on yields and reproduction traits in Gir herd, 3385 registers of milk yields (MY), milk yields until the 305 days of lactation (MY305) and lactation lengths (LL); 2394 registers of calving interval (CI) and milk yields per day of calving interval (MYCI) and 618 registers of age at first calving (AFC) had been analyzed according to mitochondrial DNA origin (indicus or taurus) and cytoplasmic lineages (foundation cows). The mitochondrial DNA origin was include in the model as fixed effect for the age to the first calving, therefore, in previous analysis, demonstrated to be significant only for this traits. Estimate of genetic components variation, parameters and prediction breeding values had been carried fitting two models animals; with and without the inclusion of the citoplasmic lineages, using restricted maximum likelihood derivative free algorithm. The citoplasmic lineage was related the 1,6%; 1,5%; 1,2%; 0%, 0% and 0%, of the phenotypic variance for traits MY, MY305, LL, CI, MYCI and AFC, even so it did not present significant in the test of reason of maximum likelihood. The correlations of ranks between the breeding values from models with and without the inclusion of the cytoplasmic lineage had been next to the unit for all the traits, however bias had been identified between genetic trends of the two models for traits MY, MY305 and LL. The mitochondrial origin, indicus or taurus were only significant (P 0,05) for the variation of the age to the first calving. The cytoplasmic lineages did not contribute significantly for the phenotypic variance of any of the traits of this study.