New Zealand Journal of Agricultural Research abstracts

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Effects of pasture and high-concentrate diets on the performance of beef cattle, carcass composition at equal growth rates, and the fatty acid composition of beef

R. W. J. Steen^1,2,3 

N. P. Lavery^1,3D. J. Kilpatrick^2,3 

M. G. Porter¹

¹Agricultural Research Institute of Northern Ireland
Hillsborough
Co Down BT26 6DR
United Kingdom
email: raymond.s@btinternet.com

²Department of Agriculture for Northern Ireland

and

³Queen's University Belfast
Newforge Lane
Belfast BT9 5PX
United Kingdom

Abstract  Two experiments were carried out to examine the effects of high quality pasture and high-concentrate diets on liveweight and carcass gain of beef cattle, carcass composition at equal carcass gain, and the fatty acid composition of beef. Heifers of late-maturing breed type (406 kg initial liveweight; Experiment 1) and steers of late-maturing breed type (460 kg initial liveweight; Experiment 2) were finished on a ryegrass pasture or a high-concentrate diet at either (1) ad libitum, (2) 85% of ad libitum intake or (3) 70% of ad libitum intake. The high-concentrate diet consisted of 95% barley-based concentrate and 5% barley straw. Carcass gain of the animals finished at pasture (648 g day^-1) was 0.78 in Experiment 1 (P < 0.001) and 0.88 in Experiment 2 (P > 0.1) of that of the animals given the high-concentrate diet ad libitum. Gains in lean meat were similar for animals finished at pasture and those given concentrates ad libitum, whereas daily fat gains were 39% lower for the animals finished at pasture (P < 0.001). At an equal rate of carcass gain, animals finished at pasture produced carcasses with a higher lean content (P = 0.03) and a lower fat content (P = 0.03) than those produced from the high-concentrate diet. Muscle from pasture-finished cattle had higher concentrations of omega-3 polyunsaturated fatty acids (PUFA) (141 versus 49 ± 8.2 mg 100 g^-1 muscle) and long-chain omega-3 PUFA (58 versus 27 ± 3.8 mg 100 g^-1 muscle) than muscle from concentrate-fed cattle. These results highlight the potential of high quality ryegrass pasture for finishing cattle, and meat from pasture-finished cattle as a source of omega-3 PUFA.

Keywords  Keywords beef cattle; pasture; concentrate diets; omega-3 fatty acids

A01028; published 30 June 2003 Received 3 September 2001: accepted 5 November 2002
New Zealand Journal of Agricultural Research, 2003, Vol. 46: 69–81
0028-8233/03/4602-0069 $7.00/0 © The Royal Society of New Zealand 2003

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