Genetic parameters for performance and carcass traits in a paternal 1 lineage of broiler.

The objective of this study was to estimate variance components for performance and carcass traits in a paternal broiler line. The (co)variance components were estimated by the restricted maximum likelihood method applied to the animal model, including the fixed effect of group (sex and hatch) and additive genetic and residual as random effects. Estimated heritability for performance traits ranged from 0.09 to 0.42. The genetic correlations between traits ranged from -0.50 to 0.97. The heritability estimates of feed intake, weight gain, and feed conversion from 35 to 41 days of age were of low magnitude. The genetic correlations among them were favorable to genetic selection. These results suggest that moderate genetic gain can be obtained to the feed intake and weight gain when the selection criterion is the body weight and prime cuts traits. The feed conversion that had low heritability estimation and low genetic correlation with the body weight and prime cut traits needs to pay greater attention due to the economic importance in the high-meat production lineage breeding programs.

Genome-wide scan reveals population stratification and footprints of recent selection in Nelore cattle.

BACKGROUND: This study aimed at (1) assessing the genomic stratification of experimental lines of Nelore cattle that have experienced different selection regimes for growth traits, and (2) identifying genomic regions that have undergone recent selection. We used a sample of 763 animals genotyped with the Illumina BovineHD BeadChip, among which 674 animals originated from two lines that are maintained under directional selection for increased yearling body weight and 89 animals from a control line that is maintained under stabilizing selection. RESULTS: Multidimensional analysis of the genomic dissimilarity matrix and admixture analysis revealed a substantial level of population stratification between the directional selection lines and the stabilizing selection control line. Two of the three tests used to detect selection signatures (FST, XP-EHH and iHS) revealed six candidate regions with indications of selection, which strongly indicates truly positive signals. The set of identified candidate genes included several genes with roles that are functionally related to growth metabolism, such as COL14A1, CPT1C, CRH, TBC1D1, and XKR4. CONCLUSIONS: The current study identified genetic stratification that resulted from almost four decades of divergent selection in an experimental Nelore population, and highlighted autosomal genomic regions that present patterns of recent selection. Our findings provide a basis for a better understanding of the metabolic mechanism that underlies the growth traits, which are modified by selection for yearling body weight.