Unravelling the complex interactions between genetics, animal age and nutrition as they impact on tissue deposition, muscle characteristics and quality of Australian sheep meat

Title
Unravelling the complex interactions between genetics, animal age and nutrition as they impact on tissue deposition, muscle characteristics and quality of Australian sheep meat
Publication Date
2007
Author(s)
Warner, RD
Pethick, David W
Greenwood, Paul
Ponnampalam, EN
Banks, Robert
Hopkins, DL
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/EA07229
UNE publication id
une:9262
Abstract
The combined effects of age and genetics and Poll Dorset sire and growth path were studied in two separate experiments (n = 595 and 627, respectively). In the first experiment, containing genotype crosses typically used in Australia (Merino, Poll Dorset, Border Leicester) and sires selected for growth or muscling, sheep were slaughtered at 4, 8, 14 and 22 months. The second experiment used Poll Dorset sires selected for high muscling, fat or growth with progeny having two levels of nutrition postweaning. Border Leicesters expressed higher levels of carcass fat percentage and intramuscular fat and produced the heaviest carcass. Merinos had the lowest subcutaneous fat depth and highest carcass lean percentage when compared at the same age. The progeny of Poll Dorset sires selected for high muscling (PDm) expressed a shift toward glycolytic fibres relative to those from Merino sires, and PDm sires produced progeny with reduced spine and limb length and higher carcass muscle : mineral ratios, suggesting skeletal stunting. Genotype meat quality differences were minimal except that PDm sire topsides were tougher and Merinos produced higher pH meat. With age (4-22 months), lambs became heavier and fatter, fibres shifted towards oxidative and away from glycolytic, muscle myoglobin increased, the meat became darker and redder and tenderness declined. Early weaning had no effect on the time to reach slaughter weight, provided nutrition was not restricted. The sire genetics influence on the carcass composition far outweighed the effect of nutrition postweaning. Lambs on a restricted diet tended to have less acceptable meat quality but this was not evident in lambs from sires selected for high fatness. Sensory tenderness was improved and intramuscular fat was higher in lamb progeny from sires selected for high fatness.
Link
Citation
Australian Journal of Experimental Agriculture, 47(10), p. 1229-1238
ISSN
1446-5574
0816-1089
1836-5787
1836-0939
Start page
1229
End page
1238

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