Prediction of marbling score and Warner-Bratzler shear force using live animal traits and carcass measurements of embryo transfer calves

摘要

This experiment involved 3/4 Angus x 1/4 Brahman, 3/4 Brahman x 1/4 Angus bovine families that were created utilizing embryo transfer together with backcross matings. Two different calf types were created from 32 families. A total of 399 carcasses were used in the marbling analysis and 298 were used in the Warner-Bratzler shear force (WBS) analysis. The individual sires and dams used in this project were selected to represent a diverse range of phenotypic traits. Birth, growth, feeding and slaughter measurements, in conjunction with class effects, were used to predict marbling (MARB) and WBS. A stepwise regression technique was utilized to determine the importance of growth and carcass measurement on marbling and WBS. An analysis of variance technique was used to determine the amount of variation in marbling that was attributable to class effects. Growth and carcass measurements where used in combination with class effects to determine the model that accounted for the highest level of variation in MARB. Ear length as a single predictor of marbling produced a R$sp2$ =.169, suggesting that if prior knowledge of genetics is not known, selecting against the phenotypic expression of Brahman inheritance, ear length, may improve marbling score. The three "best" single predictors of Warner-Bratzler shear force were gain on grass, days on grass and average daily gain on grass. Therefore, growth during the stocker period of production may prove to be a trait that producers can use to select cattle that may have more tender carcasses. The correlation coefficient for family within calf type as a single class effect for marbling was.480 indicating that 48% of the variation in marbling score could be attributed to family within calf type. Similarly, the correlation coefficient for family within calf type as a single class effect for WBS was.308. Therefore, cattle producers who are striving to increase marbling and tenderness should use sires and dams of known genetics. Heritability estimates were calculated for all traits and were similar to those seen in the literature. Genetic and phenotypic correlations revealed strong associations for growth traits and some carcass attributes.