Influence of source of lipid in cattle finishing diets on growth, carcass characteristics, meat quality, and digestion

Feed conversion is typically improved and tissue fatty acid (FA) profile is altered when lipids are added to feedlot cattle diets; however, there is limited data comparing multiple sources of dietary lipid and their effect on performance, carcass characteristics, and meat quality of feedlot cattle. Additionally, increasing the concentration of oleic acid flowing to the duodenum reportedly improves small intestinal FA digestion, potentially increasing the feeding value of lipids. Five experiments were conducted to evaluate the effects that lipids added to high-grain diets have on performance, meat quality, and FA digestion. In Exp. 1, 376 crossbred steers were fed for 132 days to evaluate the effects of lipid sources (tallow, soybeans, or three varieties of sunflower seeds) on feedlot performance and carcass characteristics. This experiment demonstrated that lipid source and FA profile influenced feedlot performance and carcass characteristics. Steers fed diets containing added lipid sources had greater growth and gain efficiency compared with negative control. Whole sunflower seeds had a greater feeding value than cracked soybeans. In Exp. 2, 94 crossbred heifers were fed different sunflower varieties for the last 52-days before slaughter. In this experiment the feeding values of the sunflower seed varieties were similar. In Exp. 3, 108 rib sections were harvested from steers (sub-sample of steers in Exp. 1) that were fed multiple lipid sources. Two steers were selected from each pen to be representative of the pen mean for yield grade and fat thickness. Steaks cut from the rib sections were analyzed for FA content and sensory attributes. From these data, it was determined that dietary lipid source influences flavor intensity and FA content of steaks. In Exp. 4, the color of fat on steaks was measured. Steaks from steers fed soybeans had a greater potential for discoloration. In Exp. 5, six multi-cannulated steers were used in a replicated, 3 x 3 Latin square experiment to measure the effects of sunflower oil on FA digestion in steers fed high-grain diets. Ruminal biohydrogenation (BH) of C18 FA was not affected by oil variety. Quantity of unsaturated FA undergoing ruminally BH was greater for oil supplementation compared with control (BH of high-oleic sunflower oil greater than that of linoleic sunflower oil). Dietary concentration of oleic acid did not impede BH. Dietary lipids alter performance and meat quality. Oils supplemented to high-grain diets undergo extensive ruminal biohydrogenation.