A multivariate study of pig carcass growth and composition: 1. production and Grading Characteristics

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Abstract
SUMMARY: Pigs from different companies (source populations) in years 3–5 of the Meat and Livestock Commission's Commercial Pig Evaluation were characterized in terms of eight production characteristics and grading measurements using canonical variates analysis in a multivariate general linear model. For pigs fed to a restricted scale, the first canonical variate was strongly associated with fat thickness measurements and the efficiency with which feed was converted into live-weight gain (FCR); the second canonical variate was associated with killing-out percentage. For pigs fedad libitum, a discriminant variate formed from the sum of the first two canonical variates was strongly associated with P2and loin fat thickness measurements and FCR, and a discriminant variate formed from the difference of the first two canonical variates was strongly associated with killing out, length and shoulder fat thickness. The first three canonical variates accounted for 88 and 90% of the variation between source populations for restricted andad-libitumfed pigs respectively. A graphical display of the source populations indicated that there were six to eight groupings depending on feeding regimen.In principal component analyses of residual variation, the first principal component on both feeding regimens was strongly associated with fat thickness measurements. The first three principal components accounted for 91 and 90% respectively of the variation for restricted andad-libitumfed pigs.