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Effects of dietary unsaturated fat and of protein source on melting point and fatty acid composition of lamb fat

Published online by Cambridge University Press:  27 March 2009

M. J. Gibney  and
J. L. L'estrange
M. J. Gibney
Affiliation:
Department of Agricultural Chemistry, University College, Glasnevin, Dublin 9
J. L. L'estrange
Affiliation:
Department of Agricultural Chemistry, University College, Glasnevin, Dublin 9
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Summary

Four groups of six store lambs were offered ad libitum a concentrate barley-based diet, supplemented with either 8% casein or 2% urea, each contributing the same level of nitrogen to the diet and each fed with or without a supplement of 5·8% sunflower oil. Daily food intake was significantly affected by treatment but there was no significant treatment effect on live-weight gain or food conversion efficiency. In rumen fluid the casein supplement resulted in more total volatile fatty acids and a greater proportion of valeric acid, while the sunflower oil supplement significantly increased the proportion of propionic acid. Sunflower oil supplementation decreased the melting point of perinephric fat by about 3 °C, associated with an increase in the proportions of palmitoleic, oleic, linoleic and linolenic acids and a decrease in the proportions of palmitic and stearic acids. Sunflower oil resulted in a smaller and nonsignificant decrease in the melting point of subcutaneous fat which was associated with an increase in the proportions of linoleic and linolenic acid and a decrease in the proportion of palmitic acid. Melting point of both fats was not affected by source of dietary nitrogen supplementation but in subcutaneous fat the urea supplement resulted in a small increase in the proportion of oleic acid and a decrease in the proportions of palmitic and palmitoleic acids. The proportions of branched-chain and oddnumbered n-acids in both fats were not affected by treatment.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 84 , Issue 2 , April 1975 , pp. 291 - 296
Copyright
Copyright © Cambridge University Press 1975

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