• Genetic relationships between carcass cut weights predicted from video image analysis and other performance traits in cattle

      Pabiou, Thierry; Fikse, W. F.; Amer, P. R.; Cromie, A. R.; Nasholm, A.; Berry, Donagh (Cambridge University Press, 2012-04)
      The objective of this study was to quantify the genetic associations between a range of carcass-related traits including wholesale cut weights predicted from video image analysis (VIA) technology, and a range of pre-slaughter performance traits in commercial Irish cattle. Predicted carcass cut weights comprised of cut weights based on retail value: lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC) and very high value cuts (VHVC), as well as total meat, fat and bone weights. Four main sources of data were used in the genetic analyses: price data of live animals collected from livestock auctions, live-weight data and linear type collected from both commercial and pedigree farms as well as from livestock auctions and weanling quality recorded on-farm. Heritability of carcass cut weights ranged from 0.21 to 0.39. Genetic correlations between the cut traits and the other performance traits were estimated using a series of bivariate sire linear mixed models where carcass cut weights were phenotypically adjusted to a constant carcass weight. Strongest positive genetic correlations were obtained between predicted carcass cut weights and carcass value (min rg(MVC)50.35; max rg(VHVC)50.69), and animal price at both weaning (min rg(MVC)50.37; max rg(VHVC)50.66) and post weaning (min rg(MVC)50.50; max rg(VHVC)50.67). Moderate genetic correlations were obtained between carcass cut weights and calf price (min rg(HVC)50.34; max rg(LVC)50.45), weanling quality (min rg(MVC)50.12; max rg(VHVC)50.49), linear scores for muscularity at both weaning (hindquarter development: min rg(MVC)520.06; max rg(VHVC)50.46), post weaning (hindquarter development: min rg(MVC)50.23; max rg(VHVC)50.44). The genetic correlations between total meat weight were consistent with those observed with the predicted wholesale cut weights. Total fat and total bone weights were generally negatively correlated with carcass value, auction prices and weanling quality. Total bone weight was, however, positively correlated with skeletal scores at weaning and post weaning. These results indicate that some traits collected early in life are moderate-to-strongly correlated with carcass cut weights predicted from VIA technology. This information can be used to improve the accuracy of selection for carcass cut weights in national genetic evaluations.
    • Genetic variation in wholesale carcass cuts predicted from digital images in cattle

      Pabiou, Thierry; Fikse, W. F.; Amer, P. R.; Cromie, A. R.; Nasholm, A.; Berry, Donagh (Cambridge University Press, 2011-06)
      The objective of this study was to quantify the genetic variation in carcass cuts predicted using digital image analysis in commercial cross-bred cattle. The data set comprised 38 404 steers and 14 318 heifers from commercial Irish herds. The traits investigated included the weights of lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC), very high value cuts (VHVC) and total meat weight. In addition, the weights of total fat and total bones were available on the steers. Heritability of carcass cut weights, within gender, was estimated using an animal linear model, whereas genetic and phenotypic correlations among cuts were estimated using a sire linear model. Carcass weight was included as a covariate in all models. In the steers, heritability ranged from 0.13 (s.e.50.02) for VHVC to 0.49 (s.e.50.03) for total bone weight, and in the heifers heritability ranged from 0.15 (s.e.50.04) for MVC to 0.72 (s.e.50.06) for total meat weight. The coefficient of genetic variation for the different cuts varied from 1.4% to 3.6%. Genetic correlations between the different cut weights were all positive and ranged from 0.45 (s.e.50.08) to 0.89 (s.e.50.03) in the steers, and from 0.47 (s.e.50.14) to 0.82 (s.e.50.06) in the heifers. Genetic correlations between the wholesale cut weights and carcass conformation ranged from 0.32 (s.e.50.06) to 0.45 (s.e.50.07) in the steers, and from 0.10 (s.e.50.12) to 0.38 (s.e.50.09) in the heifers. Genetic correlations between the same wholesale cut traits in steers and heifers ranged from 0.54 (s.e.50.14) for MVC to 0.79 (s.e.50.06) for total meat weight; genetic correlations between carcass weight and carcass classification for conformation and fat score in both genders varied from 0.80 to 0.87. The existence of genetic variation in carcass cut traits, coupled with the routine availability of predicted cut weights from digital image analysis, clearly shows the potential to genetically improve carcass value.