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Differences in the composition and tissue distribution of pig carcasses due to selection and feeding level

Published online by Cambridge University Press:  02 September 2010

N. W. Godfrey ,
P. G. Frapple ,
A. M. Paterson  and
H. G. Payne
N. W. Godfrey
Affiliation:
Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151, Australia
P. G. Frapple
Affiliation:
Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151, Australia
A. M. Paterson
Affiliation:
Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151, Australia
H. G. Payne
Affiliation:
Department of Agriculture, Baron-Hay Court, South Perth, Western Australia 6151, Australia
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Abstract

A total of 96 Large White weaner pigs, comprising equal numbers of entire males and females, and of controls and eighth generation index-selected genotypes, were fed ad libitum until 40 kg live weight. From 40 kg until slaughter at 85 kg live weight pigs within genotype and sex groups were fed either ad libitum or 2·2 times maintenance. The left sides of the carcasses were divided into shoulder, middle and ham portions and the middles further divided into eye, wedge and belly dorso-ventral portions. Tissue dissection was performed on all portions separately.

Selected pigs yielded proportionately 0·15 less fat, 0·08 more muscle, a smaller muscle: bone ratio and 4·05 mm less P2 backfat depth than the controls. When the data were adjusted to the same mean P2 fat depth, the carcasses of selected pigs had 0·07 less fat and 0·03 more muscle. There were no appreciable differences between the genotypes in cranio-caudal tissue distribution. However, there were differences in dorso-ventral tissue distribution since the middles of selected pigs had proportionately and absolutely more of each tissue in the belly. There was no evidence that selection against fat at the P2 site had caused any increase in fat lateral to the m. longissimus.

Food restriction increased carcass muscle by 0·10 and decreased fat by 0·17, but had no effect on muscle: bone ratio or cranio-caudal or dorso-ventral tissue distribution. At the same carcass side weight and P2 fat depth, restricted feeding decreased fat by 0·10 and increased muscle by 0·06 in the carcass side.

It is concluded that carcasses of the selected pigs would be undervalued relative to the controls due to less fat and more muscle at the same weight and P2 fat depth. Also, restriction on food intake can cause carcasses to be undervalued relative to feeding ad libitum.

Keywords

carcass compositionfood intakepigsselection index
Type
Research Article
Information
Animal Production , Volume 53 , Issue 1 , August 1991 , pp. 97 - 103
Copyright
Copyright © British Society of Animal Science 1991

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