Manipulating the fatty acid composition of muscle and adipose tissue in beef cattle

Scollan, ND Choi, NJ Kurt, E Fisher, AV Enser, M Wood, JD

Nd. Scollan et al., Manipulating the fatty acid composition of muscle and adipose tissue in beef cattle, BR J NUTR, 85(1), 2001, pp. 115-124

38

INGLESE

Article

Food Science/Nutrition","Endocrinology, Nutrition & Metabolism

BRITISH JOURNAL OF NUTRITION

0007-1145 → ACNP

85

1

2001

115 - 124

ISI

0007-1145(200101)85:1<115:MTFACO>2.0.ZU;2-Y

Enhancing the n-3 polyunsaturated fatty acid (PUFA) content of beef is impo rtant in view of the generally saturated nature of fatty acids in ruminant meats and the negative effect this can have on human health. This study exa mined the effects of different sources of dietary n-3 PUFA on the performan ce of steers and the fatty acid composition of m. longissimus thoracis musc le and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of four concentrates (60:40 forage:concentrate on a DM basis) containing differing sources of lipid: Megalac (16:0), lightly bruised whole linseed (18:3n-3), fish oil (20:5n-3 and 22:6n-3) and a mixtu re of linseed and fish oil (1:1, on an oil basis). Diets were formulated so that total dietary oil intake was 6 %, approximately half of which was fro m the experimental test oil. Linseed feeding not only increased the levels of 18:3n-3 in muscle phospholipid from 9.5 to 19 mg/100 g muscle but also e nhanced the synthesis of 20:5n-3, the level of which increased from 10 to 1 5 mg/100 g muscle. Linseed also increased the proportion of 18:3n-3 in musc le neutral lipid and in adipose tissue lipids by a factor of 1.64 and 1.75 respectively. Fish oil feeding doubled the proportion of 20:5n-3 and 22:6n- 3 in muscle phospholipids. The proportion of 18:1 trans in muscle neutral l ipid was higher on the n-3 PUFA diets than the control diet, 0.04 and 0.02 respectively. Despite the implied modification to rumen metabolism, lipid s ource did not affect feed intake, growth rate, cold carcass weight or carca ss fatness, but carcass conformation score was higher on fish oil treatment s (P < 0.05). However, total muscle fatty acid content was not different be tween treatments and ranged from 3.5-4.3 % of tissue weight. The increase i n n-3 PUFA in the meat produced by feeding linseed or fish oil lowered the n-6:n-3 ratio but had little effect on the P:S ratio.