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RESEARCH ARTICLE
Contents Vol 45(5)

Effects of animal age on the eating quality of sheep meat

D. W. Pethick A F , D. L. Hopkins B , D. N. D’Souza C , J. M. Thompson D and P. J. Walker E
+ Author Affiliations
- Author Affiliations

A Division of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia.

B New South Wales Department of Primary Industries, PO Box 129, Cowra, NSW 2794, Australia.

C Alltech, 68–70 Nissan Drive, Dandenong South, Vic. 3175, Australia.

D School of Rural Science and Natural Resources, The University of New England, Armidale, NSW 2351, Australia.

E Department of Primary Industries Victoria, Victorian Institute of Animal Science, Private Bag 7, Sneydes Road, Werribee, Vic. 3030, Australia.

F Corresponding author. Email: d.pethick@murdoch.edu.au

Australian Journal of Experimental Agriculture 45(5) 491-498 https://doi.org/10.1071/EA03256
Submitted: 22 November 2003  Accepted: 15 November 2004   Published: 27 June 2005

Abstract

The aim of this work was to test the effects of animal age on consumer perceptions of sheep meat quality. Experiment 1 tested eating quality scores (tenderness, liking of flavour, juiciness and overall liking) derived from untrained consumers of grilled M. longissimus lumborum (LL) or M. biceps femoris (BF) derived from Merino ewes ranging from 8.5 to 68.5 months of age. The ewes were derived from one farm and all received a pelleted diet (60% hay, 30% lupin grain and 10% barley grain) that sustained growth between 118 and 173 g/day for at least 22 days pre-slaughter. In experiment 2 consumer testing of grilled LL and roasted BF and M. semimembranosis (SM) was conducted on a commercial line of 12-month-old White Suffolk × Merino lambs (0 erupted incisor teeth) v. a line of Merino yearling sheep about 22 months old (with either 2 or 4 erupted incisor teeth). The results of experiment 1 showed a significant effect of muscle (LL>BF, P<0.001) and a cubic effect of animal age on the consumer scores for grilled steaks. The cubic relationship was due to meat from lamb (8.5 months) and hogget (20 months) having higher scores than those of older animals. There was a close relationship between the objective measures of tenderness and the consumer tenderness score (r2 = 0.53, P<0.001). Results of experiment 2 indicated no significant difference between the grilled LL for the crossbred lamb and 22-month-old (2–4 teeth) Merino yearling sheep. However, the consumer scores for the roasted BF and SM were significantly depressed in the 2–4 tooth yearling Merino categories. In conclusion, this work clearly underpins the current Australian definition of lamb, lamb having better eating-quality attributes than older animals with fully erupted permanent incisor teeth, particularly in muscles from across the carcass. However, this work also highlights the eating quality attributes of older sheep (6 or more permanent incisor teeth) particularly for the LL, and suggests that negative influences of flavour associated with older sheep meat are minimal when the product is served in the absence of subcutaneous and intermuscular fat. Finally, the results suggest the possibility of a new ‘yearling’ sheep meat category based on animals in the 2–4-tooth dentition category.


Acknowledgments

The manager and staff of Cosign are acknowledged for their skills in sample preparation for consumer testing. The skilled technical assistance and dedication of Mr Malcolm Boyce, Mrs Barbara Waldoch, Mr Ken Chong, Mr Robert Davidson, Mr Tim Hilder and Mr Andrew Blakey is gratefully acknowledged. Research students at Murdoch University are thanked for their generous help at slaughter: Ms Alexandra Pugh, Ms Kelly Pearce and Ms Jeisane Accioly. The Hewitt family is thanked for supply, managing and finishing the sheep on their farm near York, Western Australia. The manager and staff at Hillside Meats are gratefully acknowledged for their enormous cooperation during the slaughter and bone out periods.


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