Effect of supplemental fat from dried distillers grains with solubles or corn oil on cow performance, IGF-1, GH, and NEFA concentrations1

Research has demonstrated that supplemental fat and(or) changes in growth hormone (GH) or insulinlike growth factor-1 (IGF-1) concentrations may affect reproductive performance in beef females. Dried distillers grains with solubles (DDGS) contain approximately 10% to 15% fat; however, minimal research to date has investigated DDGS specifically as a supplemental fat source. The objective of this experiment was to investigate whether supplemental fat from either DDGS or raw corn oil impacts cow growth performance and plasma GH, IGF-1, or non-esterified fatty acid (NEFA) concentrations. Sixty open beef cows [body weight (BW) = 553.5 ± 38.7 kg; body condition score (BCS) = 5.4 ± 0.53] were stratified by BW and BCS and allotted to 15 pens (n = 4 per pen; 14.6 x 37.2 m). Pens were randomly assigned to one of three dietary treatments: 1) DDGS, 2) a combination of high-protein dried distillers grain, corn bran, and corn oil (OIL), or 3) a combination of high-protein dried distillers grain and corn bran (HPBRAN). The DDGS, OIL, and HPBRAN treatments each comprised 35% of the diet dry matter (DM). Thirty-five percent was selected based upon the sulfur (S) content of dietary ingredients in the DDGS treatment and water, estimated water intake, and the maximum tolerable S concentration for cattle on forage-based diets (0.5%). In addition to dietary treatments, cattle were provided grass hay [7.7% crude protein (CP)] and a pelleted supplement containing vitamins and minerals as part of a totally mixed ration. Cows were fed once daily, in the morning, for 60 d. All diets were iso-nitrogenous (15.3% CP from d 0 to 47 and 15.1% from d 48 to 60) and total fat concentrations were 5.1% for DDGS and OIL and 3.5% for HPBRAN. Weights and blood samples were recorded prior to feeding on d -1, 0, 28, 59, and 60. Dry matter intake, average daily gain, final BW, and gain:feed were not affected by treatment. Treatment had no effect on plasma GH, IGF-1, or NEFA concentrations. These results suggest that providing low concentrations of supplemental fat as DDGS or raw corn oil to a forage-based diet does not influence growth performance, plasma GH, IGF-1, or NEFA concentrations in open beef cows.