Abstract
A study was conducted to investigate the influence of an ionophore antibiotic and lipid saturation within a standard finishing diet on the conjugated linoleic acid (CLA) content of lambs’ meat. Two identical sheep grower diets containing 145 g CP, 282 g NDF and 45 g EE per kg DM were formulated. One diet contained no ionophore antibiotic and the other monensin-Na included at 165 g/ton. These two basal diets were supplemented, according to a 2 x 3 factorial design, with three lipid sources [i.e. 20 g/kg of either beef tallow, sunflower oil or a CLA oil concentrate] differing in saturation level and fatty acid profile. Sixty South African Mutton Merino lambs (31.15 ± 2.83 kg) were randomly allocated to the six treatments. After dietary adaptation of 10 days, the lambs received their respective treatment diets for the remaining period of 51 days. At the end of the study seven lambs (45.11 ± 2.99 kg) were randomly selected per treatment and slaughtered. Muscle and subcutaneous fat tissue from loin chops of each carcass were used for lipid extraction and fatty acid analysis. The supplementation of CLA oil in the diet resulted in a significantly lower vaccenic acid concentration of lamb muscle tissue. In contrast, supplementing sunflower oil increased the linoleic acid concentration of only the subcutaneous fat tissue significantly. Sunflower- and CLA oil supplementation increased the cis-9, trans-11 CLA isomer of both subcutaneous fat and muscle tissues, whereas only the CLA concentrate increased the trans-10, cis-12 isomer of both mentioned tissues significantly. The dietary inclusion of monensin-Na decreased the vaccenic-, linoleic- and CLA (cis-9, trans-11 isomer) concentrations of both lamb subcutaneous fat and muscle tissues significantly. The manipulation of the CLA content of lamb seems to be effective when adding either sunflower oil or a CLA oil concentrate to the finishing diet of lambs. However, this effect is inhibited by the addition of monensin-Na to the same diet.Keywords: Conjugated linoleic acid, cis-9, trans-11 CLA isomer, tallow, sunflower oil, subcutaneous fat
Highlights
The past few decades have been characterized by an increased awareness concerning the nutritional aspects and health implications of ruminant products for human consumption
The major fatty acids that play a role in the biohydrogenation pathway of conjugated linoleic acid (CLA) were included
The linoleic acid (C18:2 c9, 12 n-6) concentration was increased (P
Summary
The past few decades have been characterized by an increased awareness concerning the nutritional aspects and health implications of ruminant products for human consumption. There is recognition that human health benefits from the regular consumption of polyunsaturated fatty acids (PUFA). Wahle et al (2004) reported in a review that the trans-10, cis-12 CLA isomer could induce an increase in isoprostane secretion in the urine of humans, an indicator of non-enzymatic eicosanoid formation and of lipid peroxidation. This same isomer could elicit pro-carcinogenic effects on colon and prostate
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