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Effect of lamb growth rate and growth pattern on carcass fat levels

Published online by Cambridge University Press:  02 September 2010

D. M. B. Chestnutt
D. M. B. Chestnutt
Affiliation:
Agricultural Research Institute of Northern Ireland, Hillsborough, Co. Down BT26 6DR
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Abstract

A total of 252 lambs was subjected to two contrasting growth rates (high and low) for 7 weeks commencing at 6 weeks of age, factorially arranged with two contrasting growth rates (high and low) from 13 weeks to slaughter. Growth rate was controlled either by weaning lambs at 6 weeks and feeding indoors throughout on differing levels of a concentrate diet (84 lambs in experiment 1) or by grazing at differing sward heights up to weaning at 13 weeks after which weaned lambs were grazed at differing sward heights and where necessary housed from early October and offered differing levels of concentrate and silage (168 lambs in experiment 2). Lamb slaughter weights on each growth rate treatment covered the range 40 to 48 kg live weight.

Increasing the growth rate between 6 and 13 weeks from 213 to 320 glday in experiment 1 and from 191 to 291 g/day in experiment 2 did not significantly affect the fat depth measured at various locations throughout the carcass, the weight of perinephric and retroperitoneal fat, fat grade or the total lipid content of soft tissue dissected from the shoulder joint when lambs were taken to slaughter weights. Increasing the growth rate between 13 weeks and slaughter from 136 to 338 g/day in experiment 1 and from 99 to 146 g/day in experiment 2 significantly increased the depth of carcass fat and fat grade but, though lipid content of the tissue in the shoulder also increased, this difference was not significant.

Carcass fat depth, perinephric and retroperitoneal fat, fat grade and lipid content of the shoulder tissue increased as slaughter weight increased. The effect of carcass weight on carcass fat was greater on the high plane of feeding from 13 weeks than on the low plane. For example, mean fat depth increased by 0·52 mm/kg increase in carcass weight on the high plane compared with 0·13 mm/kg on the low plane.

Comparing the effect of plane of feeding and carcass weight on carcass fat depth the high finishing plane of feeding had an effect equivalent to an increase of 3·8 kg carcass weight. The equivalent figure for the depth of tissue over the 12th rib was 2·8 kg while in relation to fat grade the effect was smaller at 1·0 kg carcass weight.

Keywords

carcass fatgrowth ratelambsplane of nutrition
Type
Research Article
Information
Animal Production , Volume 58 , Issue 1 , February 1994 , pp. 77 - 85
Copyright
Copyright © British Society of Animal Science 1994

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References

Andrews, R. P. and Ørskov, E. R. 1970. The nutrition of the early weaned lamb. 2. The effect of dietary protein concentration, feeding level and sex on body composition at two live weights. Journal of Agricultural Science, Cambridge 75: 19–26.CrossRefGoogle Scholar
Black, J. L. 1974. Manipulation of body composition through nutrition. Proceedings of the Australian Society of Animal Production 10: 211–218.Google Scholar
Burton, J. H. and Reid, J. T. 1969. Interrelationships among energy input, body size, age and body composition of sheep. Journal of Nutrition 97: 517–524.CrossRefGoogle ScholarPubMed
Butler-Hogg, B. W. and Johnsson, I. D. 1986. Fat partitioning and tissue distribution in crossbred ewes following different growth paths. Animal Production 42: 65–72.Google Scholar
Doney, J. M., Milne, J. A., Maxwell, T. J., Sibbald, A. M. and Smith, A. D. M. 1988. The effects of live weight at weaning on growth rate and carcass composition at different stages of maturity in Scottish Blackface lambs fed on two different diets. Animal Production 47: 401–409.Google Scholar
Hodge, R. W. and Star, M. 1984. Comparison of the fat status of lambs during continuous growth and following nutritional restriction and subsequent realimentation. Australian Journal of Experimental Agriculture and Animal Husbandry 24: 150–155.CrossRefGoogle Scholar
Lawlor, M. J. and Hopkins, S. P. 1981. The influence of perinatal under-nutrition of twin-bearing ewes on milk yields and lamb performance and the effects of postnatal nutrition on liveweight gain and carcass gain and carcass compostion. British Journal of Nutrition 45: 579–586.CrossRefGoogle Scholar
Lee, G. J. 1986. Growth and carcass composition of ram and wether lambs fed at two levels of nutrition. Australian Journal of Experimental Agriculture 26: 275–278.CrossRefGoogle Scholar
Little, D. A. and Sandland, R. L. 1975. Studies on the distribution of the body fat in sheep during continuous growth and following nutritional restriction and rehabilitation. Australian Journal of Agricultural Research 26: 363–374.CrossRefGoogle Scholar
Morgan, J. A. and Owen, J. B. 1973. Nutrition of artificially reared lambs. 3. The effect of sex on performance and carcass composition of lambs subjected to different nutritional treatments. Animal Production 16: 49–57.Google Scholar
Murray, D. M. and Slezacek, O. 1976. Growth rate and its effect on empty body weight, carcass weight and dissected carcass composition of sheep. Journal of Agricultural Science, Cambridge 87: 171–179.CrossRefGoogle Scholar
Purchas, R. W. 1978. Some effects of nutrition and castration on meat production from male Suffolk cross (Border Leicester - Romney cross) lambs. 1. Growth and carcass quality. New Zealand Journal of Agricultural Research 21: 367–376.CrossRefGoogle Scholar
Theriez, M., Villette, Y. and Castrillo, C. 1982. Influence of metabolizable energy content of the diet and feeding level on lamb performance. 1. Growth and body composition. Livestock Production Science 9: 471–485.CrossRefGoogle Scholar