Fatty Acid Profile of Omasum from Cattle Fed with Soybean Oil, Selenium and Vitamin E

The objective of this study was to evaluate the concentration of fatty acid in the omasum when diets with 6% soybean oil and with or without supplementation of organic selenium and vitamin E were fed. Five cannulated steers with an average initial body weight of 398 ± 28.7 kg were subjected to a 5 x 5 Latin Square with 21 days periods: 14 days of adaptation to diets and 7 days of sampling. Diets consisted of 65% concentrate and 35% corn silage formulated to be isonitrogenous (14.4% CP). Steers were assigned to dietary treatments: without additional oil; 6% soybean oil; 6% soybean oil plus vitamin E; 6% soybean oil plus selenium; 6% soybean oil plus vitamin E plus selenium. The additives were offered daily with 1500 IU vitamin E and 5 g selenium per animal. Digesta of the omasum were collected for long chain fatty acids analysis using gas chromatography. The model included the fixed effects of diet and period and animal as a random effect, and was analyzed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC). The soybean oil diet had lower concentration of lauric acid (C12:0) (0.13 and 0.35; P < 0.01), myristic (C14:0) (0.47 and 1.21; P < 0.01), pentadecanoic (C15:0) ( 0.20 and 0.60; P < 0.01), palmitic C16:0) (12.75 and 15.6; P < 0.01), palmitoleic (C16:1) (0.06 and 0.16; P = 0.01), heptadecanoic (C17:0) (0.22 and 0.34; P = 0.02), oleic (2.30 and 3.85; C18:1 c9) (P < 0.01), and linoleic (C18:2 c9,12) ( 2.11 and 3.09; P = 0.01) than the diet without additional oil. However, the soybean oil diet had higher concentrations of elaidic (C18:1 t9) (0.61 and 0.27; P = 0.02), CLA C18:2 t10, c12 (0.04 and not detected; P = 0. 01) and polyunsaturated fatty acids (PUFA) (2.66 and 3.75; P < 0.01) than the diet without additional oil. The supplementation with selenium tended to increase the concentration of C18:2 c9,12 (2.40 and 1.72; P = 0.07) and PUFA (3.0 and 2.33; P = 0.07) compared to the diet without selenium. In conclusion, supplementation with soybean oil and selenium can contribute to the increase concentration of PUFA in the digesta of the omasum, which may positively impact the concentration of PUFA in the subcutaneous and intramuscular fat of beef cattle.