Effects of reduced-fat modified wet distillers grains with solubles on the performance of limit-fed beef cows1

The objective of this study was to evaluate 3 inclusion rates for modified wet distillers grains with solubles containing 5.6 to 8.0% fat (WDGS) when limit-fed to beef cows during late gestation and early lactation. Angus × Simmental crossbred cows (n = 128) in the third trimester were blocked by parity (first parity and 2 or more parities) and stratified within parity by BW, subject to variation in BCS, to 16 pens. Four diets were fed until completion of a timed AI. Control cows were fed corn silage-, shelled corn-, and soybean meal-based diets to provide 12% CP [treatment (T) 1]. In the treatment diets, WDGS replaced shelled corn, soybean meal, and a portion of the corn silage to provide 12% (T2), 16% (T3), or 20% CP (T4). Analyzed CP values were 12.0, 12.5, 15.7, and 19.0%, for T1, T2, T3, and T4, respectively. Mean DMI per day was 7.80 ± 1.01, 7.96 ± 1.01, 8.55 ± 1.28, and 8.63 ± 1.11 kg for T1, T2, T3, and T4, respectively. No differences (P > 0.05) between treatments were observed for calving ease score, calf birth weight, calf BW, and cow BCS at the end of the feeding period. There was a linear (P = 0.03) increase in cow BW change in cattle fed increasing levels of WDGS and a quadratic response (P = 0.03) in milk production, with production increasing in T3 compared with T4 and T2 cattle. Cows fed increased levels of WDGS performed equally or superior to cows fed shelled corn- and soybean meal-based diets.