Methionine supplementation during late gestation in March calving Angus crossbred beef heifers and cows

Abstract The objectives of these two studies were to evaluate the impact of excess Met (methionine) supplementation during late gestation on intake, body weight (BW), average daily gain (ADG), reproductive performance, and subsequent calf performance in artificially inseminated heifers and naturally bred cows. In Exp. 1, a 3-yr study used 38 pregnant Black Angus crossbred heifers/yr (n = 113) in a Calan gate feeding system. There was a 20-d acclimation period before the 93 ± 6-d trial began 161 ± 6 d after artificial insemination. Heifers were assigned to one of three treatments and fed ad libitum hay with either no supplement (HAY1), 0.9 kg/d dried distillers’ grain (DDG), or 0.9 kg/d dried distillers’ grain with 30 g/d of a methionine hydroxy analog (MET1). In Exp. 2, a 3-yr study used 145 pregnant Red Angus crossbred cows/yr (n = 436) on upland winter range fed one of five treatments: no supplement (NS), ad libitum hay (HAY2), 0.45 kg/d of a distillers’-based cube (CAKE1), 0.9 kg/d of a distillers-based cube (CAKE2), or 0.9 kg/d of a distillers’-based cube plus 30 g/d of a methionine hydroxy analog (MET2). In Exp. 1, hay dry matter intake during the trial period was not different (P = 0.38) but final BW and ADG were greater (P < 0.01) in DDG and MET1 compared to HAY1 heifers. In Exp 2, NS cows had significantly lower body condition score (BCS) at the end of the trial period than other treatments (P < 0.01). Similarly, pre-calving and pre-breeding BW were also less in NS cows than other treatments (P < 0.01). Pregnancy rates for HAY2 (94%), CAKE1 (95%), CAKE2 (94%), and MET2 (94%) were significantly greater (P < 0.01) than NS (80%) cows. There was a tendency (P = 0.09) for calves from HAY2 cows to have greater marbling compared to NS. There were no other differences in calving performance or progeny carcass characteristics in either experiment. While late gestational protein supplementation impacted BW and ADG in heifers, and BW and BCS in cows, there were no significant differences in the dam or progeny due to Met supplementation.