Intramuscular fat levels in sheep muscle during growth
M. J. McPhee A B , D. L. Hopkins A C and D. W. Pethick A D EA Australian Sheep Industry Cooperative Research Centre, Armidale, NSW 2350, Australia.
B NSW Department of Primary Industries, Beef Industry Centre of Excellence, JSF Barker Building, NSW 2351, Australia.
C NSW Department of Primary Industries, Centre for Sheep Meat Development, Cowra, NSW 2794, Australia.
D Department of Veterinary Biology and Biomedical Science, Murdoch University, South Street, Murdoch, WA 6150, Australia.
E Corresponding author. Email: D.Pethick@murdoch.edu.au
Australian Journal of Experimental Agriculture 48(7) 904-909 https://doi.org/10.1071/EA08046
Submitted: 22 January 2008 Accepted: 21 April 2008 Published: 20 June 2008
Abstract
A 5 × 4 factorial experiment was designed in which lambs representing five genotypes were slaughtered at four ages (110, 236, 412 and 662 days of age). The genotypes represented were Poll Dorsetgrowth × Border Leicester Merino, Poll Dorsetgrowth × Merino, Poll Dorsetmuscling × Merino, Merino × Merino and Border Leicester × Merino. Both sexes (ewes and wethers) were represented for each genotype and slaughter age combination. In total, 595 animals were slaughtered and the carcass composition and intramuscular fat were measured. Carcass composition [fat, ash and protein (lean)] was determined by dual energy X-ray absorptiometry, with the intramuscular fat percentage determined using near-infrared spectroscopy following removal and weighing of the entire longissimus thoracis et lumborum (LL) muscle. Analysis revealed that the proportion of intramusular fat in the loin relative to total carcass fat decreases as animals mature, thus indicating that intramusular fat deposition occurs early in the maturation of sheep. Furthermore, as animals became heavier and older the accretion rate of intramuscular fat in the LL muscle slowed down. Both genotype (P < 0.05) and sex (P < 0.001) were found to impact on this pattern, with Border Leicester × Merino animals exhibiting the largest increase in intramuscular fat proportion in the LL muscle (4.92 and 5.50% at 22 months of age for ewes and wethers, respectively). The Poll Dorsetgrowth × Border Leicester Merino animals were found to have the greatest absolute levels of intramuscular fat in the whole LL muscle (80.95 and 97.60 g at maturity for ewes and wethers, respectively). The amount of intramuscular fat significantly increased as the sheep became older and fatter; however, these differences were quantitatively small. As such, finishing prime lambs to high levels of total carcass fatness would have little effect on any eating quality benefits associated with increased intramuscular fat proportion.
Acknowledgements
Technical support for this study was provided by David Stanley, Leonie Martin, Edwina Toohey, Tony Markham, Jayce Morgan, Sally Martin, Brent McLeod, Steve Sinclair, Joe Brunner, Stuart McClelland and Amanda Lang (NSW Department of Primary Industries), Kirstie Martin and Kirsty Thomson (formerly University of New England), Peter Allingham (CSIRO) and Tracy Lamb and Rachel McGee funded by CSIRO, Drs Eric Ponnampalam, Danny Suster and Matt McDonagh, Matt Kerr, Dete Hasse, Oliver Fernando, Erin Rutty and Fahri Fahri (DPI, Victoria), Dr Greg Nattrass (SARDI) and Dr Martin Cake and Mal Boyce (Murdoch Uni). Testing of samples for IMF was undertaken by the meat science section at the University of New England. The excellent co-operation of employees and management from Junee and Hillside abattoirs is gratefully acknowledged. The study was funded by NSW Department of Primary Industries, Meat and Livestock Australia and the Australian Sheep Industry Cooperative Centre.
Cianzio DS,
Topel DG,
Whitehurst GB,
Beitz DC, Self HL
(1985) Adipose tissue growth and cellularity: Changes in bovine adipocyte size and number. Journal of Animal Science 60, 970–976.
|
CAS |
PubMed |
Díaz MT,
Álvarez I,
De la Fuente J,
Sañudo C, Campo MM , et al.
(2005) Fatty acid composition of meat from typical lamb production systems of Spain, United Kingdom, Germany and Uruguay. Meat Science 71, 256–263.
| Crossref | GoogleScholarGoogle Scholar |
Dunshea FR,
Suster D,
Eason PJ,
Warner RD,
Hopkins DL, Ponnampalam EN
(2007) Accuracy of dual energy X-ray absorptiometry, weight, longissimus lumborum muscle depth and GR fat depth to predict half carcass composition in sheep. Australian Journal of Experimental Agriculture 47, 1165–1171.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Fernandez X,
Monin G,
Talmant A,
Mourot J, Lebret B
(1999) Influence of intramuscular fat content on the quality of pig meat – 2. Consumer acceptability of m. longissimus lumborum. Meat Science 53, 67–72.
| Crossref | GoogleScholarGoogle Scholar |
Hood RL, Allen CE
(1973) Cellularity of bovine adipose tissue. Journal of Lipid Research 20, 605–610.
Hopkins DL, Fogarty NM
(1998) Diverse lamb genotypes- 2. Meat pH, colour and tenderness. Meat Science 49, 477–488.
| Crossref | GoogleScholarGoogle Scholar |
Hopkins DL,
Hegarty RS, Farrell TC
(2005a) Relationship between sire estimated breeding values and the meat and eating quality of meat from their progeny grown on two planes of nutrition. Australian Journal of Experimental Agriculture 45, 525–533.
| Crossref | GoogleScholarGoogle Scholar |
Hopkins DL,
Walker PJ,
Thompson JM, Pethick DW
(2005b) Effect of sheep type on meat eating quality of sheep meat. Australian Journal of Experimental Agriculture 45, 499–507.
| Crossref | GoogleScholarGoogle Scholar |
Hopkins DL,
Hegarty RS,
Walker PJ, Pethick DW
(2006) Relationship between animal age, intramuscular fat, cooking loss, pH, shear force and eating quality of aged meat from sheep. Australian Journal of Experimental Agriculture 46, 879–884.
| Crossref | GoogleScholarGoogle Scholar |
Hopkins DL,
Stanley DF,
Martin LC, Gilmour AR
(2007a) Genotype and age effects on sheep meat production. 1. Production and growth. Australian Journal of Experimental Agriculture 47, 1119–1127.
| Crossref | GoogleScholarGoogle Scholar |
Hopkins DL,
Stanley DF,
Martin LC,
Toohey ES, Gilmour AR
(2007b) Genotype and age effects on sheep meat production. 3. Meat quality. Australian Journal of Experimental Agriculture 47, 1155–1164.
| Crossref | GoogleScholarGoogle Scholar |
Johnson ER,
Butterfield RM, Pryor WJ
(1972) Studies of fat distribution in the bovine carcass I. The partition of fatty tissues between depots. Australian Journal of Agricultural Research 23, 381–388.
| Crossref | GoogleScholarGoogle Scholar |
Martínez-Cerezo S,
Sañudo C,
Panea B,
Medel I,
Delfa R,
Sierra I,
Beltrán JA,
Cepero R, Olleta JL
(2005) Breed, slaughter weight and ageing time effects on physico-chemical characteristics of lamb meat. Meat Science 69, 325–333.
| Crossref | GoogleScholarGoogle Scholar |
Okeudo NJ, Moss BW
(2007) Intramuscular lipid and fatty acid profile of sheep comprising four sex-types and seven slaughter weights produced following commercial procedure. Meat Science 76, 195–200.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Perry D,
Shorthose WR,
Ferguson DM, Thompson JM
(2001) Methods used in the CRC program for the determination of carcass yield and beef quality. Australian Journal of Experimental Agriculture 41, 953–957.
| Crossref | GoogleScholarGoogle Scholar |
Pethick DW,
Hopkins DL,
D’Souza DN,
Thompson JM, Walker PJ
(2005) Effect of animal age on the eating quality of sheep meat. Australian Journal of Experimental Agriculture 45, 491–498.
| Crossref | GoogleScholarGoogle Scholar |
Ponnampalam EN,
Hopkins DL,
Butler KL,
Dunshea FR, Warner RD
(2007a) Genotype and age effects on sheep meat production 2. Carcass quality traits. Australian Journal of Experimental Agriculture 47, 1147–1154.
| Crossref | GoogleScholarGoogle Scholar |
Ponnampalam EN,
Hopkins DL,
Dunshea FR,
Pethick DW,
Butler KL, Warner RD
(2007b) Genotype and age effects on sheep meat production 4. Carcass composition predicted by dual energy X-ray absorptiometry. Australian Journal of Experimental Agriculture 47, 1172–1179.
| Crossref | GoogleScholarGoogle Scholar |
Ponnampalam EN,
Butler KL,
Hopkins DL,
Kerr MG,
Dunshea FR, Warner RD
(2008) Genotype and age effects on sheep meat production 5. Lean meat and fat content in the carcasses of Australian sheep genotypes at 20‐, 30‐ and 40‐kg carcass weights. Australian Journal of Experimental Agriculture 48, 933–937.
Suster D,
Leury BJ,
Hofmeyr CD,
D’Souza DN, Dunshea FR
(2004) The accuracy of dual energy X-ray absorptiometry (DXA), weight, and P2 back fat to predict half-carcass and primal-cut composition in pigs within and across research experiments. Australian Journal of Agricultural Research 55, 973–982.
| Crossref | GoogleScholarGoogle Scholar |
Thompson JM
(2002) Managing meat tenderness. Meat Science 62, 295–308.
| Crossref | GoogleScholarGoogle Scholar |
Thompson JM
(2004) The effects of marbling on flavour and juiciness scores of cooked beef, after adjusting to a constant tenderness. Australian Journal of Experimental Agriculture 44, 645–652.
| Crossref | GoogleScholarGoogle Scholar |
Thompson JM,
Butterfield RM, Perry D
(1987) Food intake, growth and body composition in Australian Merino sheep selected for high and low weaning weight. Animal Production 45, 49–60.
