Effect of high oil corn in the diets of Nellore steers on growth performance, carcass characteristics, meat quality, and longissimus muscle fatty acid profile

The objective in this study was to evaluate the effects of substituting high oil corn (HOC) for typical corn (TC) on performance, carcass characteristics, meat quality, and longissimus muscle (LM) fatty acid profile of Nellore steers fed diets containing different amounts of corn. Forty-eight individually fed Nellore steers (441±32kg initial body weight) were allocated by body weight to four pens equipped with electronic gates in a randomized complete block design with six treatments in a 2×3 factorial arrangement of treatments, with two corn types (CT) and three corn levels (CL). Treatments consisted of diets containing 25, 40, or 55% TC or HOC on a dry matter (DM) basis. Animals were confined for 84 days so that DM intake and average daily gain (ADG) were measured individually. After the feedlot period, animals were slaughtered at a commercial slaughterhouse, carcass characteristics were evaluated, and LM samples were collected for further analyses of meat quality and fatty acid profile. Statistical analyses were conducted using the MIXED procedure of SAS. No differences among CL and CT were observed for DM intake, metabolizable energy intake, gain to feed ratio, and dietary net energy for maintenance and gain. Steers receiving HOC had greater ADG in comparison with those fed TC when CL was 25%, but no differences were observed when CL was 40 or 55%. Cooking loss and LM redness were linearly decreased (P≤0.05) with the increasing CL. No effects of CL and CT were observed for any other carcass characteristics and meat quality variables. The LM proportions of stearic, linolenic, and total omega-6 fatty acids, as well as omega-6 to omega-3 fatty acids ratio (n-6:n-3), were linearly increased (P≤0.04) as CL increased, whereas conjugated linoleic acid (CLA) proportions showed a quadratic response (P<0.01) to corn inclusion, with lower values observed for steers fed 40% corn. Longissimus muscle proportions of myristic and palmitic acids were decreased (P≤0.02), whereas proportions of CLA, total omega-6, and total polyunsaturated fatty acids, as well as n-6:n-3, were increased (P≤0.04) when TC was replaced with HOC. In conclusion, replacing TC with HOC in the diets of Nellore steers fed different corn levels had no effects on animal performance, carcass characteristics, and meat quality, but improved LM fatty acid profile, which suggests that the produced beef might be healthier for consumers.