Effects of dietary sesame oil on growth performance and fatty acid composition of muscle and tail fat in fattening Chaal lambs

• Sesame oil (SO) feeding did not affect lamb performance, but increased kidney fat.
• SO feeding increased the serum total cholesterol and high density lipoproteins.
• SO feeding decreased the molar ratio of ruminal propionate.
• SO feeding improved the concentration of CLA cis-9, trans-11 in meat and tail fat.

This experiment was carried out to study the effect of sesame oil (SO) supplementation on performance and fatty acid composition of meat and tail fat in Iranian Chaal lambs. Eighteen lambs were fed one of the three isocaloric and isonitrogenous diets containing 0 (control), 25 and 50 g SO per kilogram diet in a completely randomized design for 84 days. There were no substantial effects on animal performance and their carcass and non-carcass measurements, except for kidney fat weight which linearly increased (P = 0.05) by increasing level of SO. Supplementation of SO was resulted a decrease in the molar ratio of ruminal propionate (P = 0.01), whereas the ruminal acetate:propionate ratio (P = 0.03), serum total cholesterol (P = 0.01) and high density lipoproteins (HDL) were increased linearly (P < 0.01). The inclusion of SO up to 50 g/kg in diet linearly decreased concentrations of C15:0 (P = 0.02, P < 0.01), C16:0 (P = 0.04, P = 0.05), C16:1 (P = 0.02, P = 0.02), C17:0 (P = 0.03, P < 0.01) and C17:1 (P = 0.02, P < 0.01), and increased concentrations of C18:1 trans (P < 0.01) and conjugated linoleic acid (CLA) C18:2 cis-9, trans-11 (P ≤ 0.01) in both intramuscular and tail fat. Increasing level of SO in the diets had quadratic (P = 0.05) effect on C18:0 and linearly increased (P = 0.05) polyunsaturated fatty acids (PUFA), and decreased saturated fatty acids (SFA) (P = 0.03) as well as atherogenicity index (P = 0.05) in tail fat. Our results indicated that increasing level of SO up to 50 g per kg diet may improves tail fat and intramuscular CLA cis-9, trans-11 in young fattening Chaal lambs without affecting animal performance and with little effect on fat deposition.