Influence of steam-flaked sorghum grain and supplemental fat on performance of dairy cows in early lactation.

Effects of sorghum grain processing and fat supplementation on milk yield and composition and nutrient digestibilities were studied. Thirty-six Holstein cows were assigned at 5 d of lactation for 91 d to treatment: 1) dry-rolled sorghum, no added fat; 2) dry-rolled sorghum plus Ca salts of long-chain fatty acids; 3) steam-flaked sorghum, no added fat; and 4) steam-flaked sorghum plus Ca salts of long-chain fatty acids. Fat increased ether extract in diets from 5.7 to 7.5% of DM. Milk yield was 4.0 kg/d (12%) higher for cows fed steam-flaked than dry-rolled sorghum. Fat tended to decrease milk yield because of lower DMI, and feed efficiencies increased 15%. Milk protein decreased .14% on dry-rolled sorghum with added fat, but only .01% on the steam-flaked diet. Milk protein yield was higher for cows fed flaked than rolled sorghum. Flaking decreased milk fat percentage, but not yield. Added fat decreased shorter chain fatty acids in milk (C4 to C14), but oleic acid increased. Flaking increased C10, C12, and C14, but decreased oleic acid. Digestibilities for DM, CP, starch, and ether extract were higher for flaked and fat-supplemented diets. Flanking of sorghum prevented the milk protein decrease reported for early lactation cows fed added fat.