Epsilon Open Archive

Abstract

In this thesis we investigated the feasibility of breeding for phenotypes predicted from video image analysis (VIA). In meat factories in Ireland, digital images are routinely
taken after slaughter to derive EUROP conformation and fat grades. Two datasets (1,048 carcasses in total) on individual carcass dissections were made available for this
study, one by a research center and the other by a commercial partner. Dissection data consisted of eight and six primal cuts taken in the hind- and fore-quarter, respectively, and analyses revealed significant genetic variations in these data. Heritabilities of primal cut weights ranged from 0.03 to 0.83 in the fore-quarter cuts, and from 0.14 to 0.86 in the hind-quarter cuts. Primal cut weights were subsequently grouped into four wholesale cut weights according to their retail values: lower value cuts, medium value cuts, high value cuts, and very high value cuts. Equations to predict wholesale cut weights were subsequently derived from VIA image parameters. Accuracy of
prediction were >0.84 and >0.72 in the steer and heifer datasets, respectively.

Genetic analysis of the wholesale cut weights predicted in a large national dataset of steers and heifers revealed heritabilities of 0.18, 0.27, 0.40, and 0.17 for lower value
cuts, medium value cuts, high value cuts, and very high value cuts, respectively.
Genetic correlations among predicted wholesale cut weights ranged from 0.45 to 0.89 across genders. Predicted wholesale cut weights were also strongly genetically correlated with animal price at weaning age (0.37 to 0.66), as well as price at postweaning age (0.50 to 0.67) suggesting a benefit of indirect selection especially where
data on carcass cut weights were not yet available.

Including predicted wholesale cut weights in a selection criteria increased genetic gain for carcass traits over and above the current selection practice of selection on EUROP conformation score. Expanding knowledge on wholesale cut weights and extending it to meat quality traits is an attractive option for Ireland.