Comparative Acceptability and Nutritive Value of Barley, Wheat Mixed Feed, and a Mixed Concentrate Ration in Meal and Pelleted Forms for Lactating Cows1,2

Abstract

Grain rations consisting of 98% barley, 98% wheat mixed feed, and a control mixture of barley, wheat, peas, and cottonseed meal, fed in meal and pelleted forms, were compared in digestion, lactation, and acceptability trials. Alfalfa hay was fed as the only roughage with each grain mixture at a 55 :45 ratio in the lactation and digestion trials and at a 30:70 ratio in the acceptability trial.Digestibility of dry matter, energy, and total digestible nutrients content of wheat mixed feed rations were lower than barley or control rations. Fed as a meal, wheat mixed feed was consumed at a lower rate than all other grain rations (P<.05) in the acceptability trial.Cows fed pelleted grain rations in the lactation trial produced more milk, protein, solids-not-fat, fat, and fat-corrected milk than those fed meal rations (P<.10). Differences in production of fat-correeted-milk, percentage solids-not-fat, and percentage protein of milk among meal and pelleted rations were small (P>.10). Pelleting the grain rations resulted in the greatest depression of milk fat percentage for cows in the acceptability trial. Fat depression was not as great for cows on the acceptability trial fed wheat mixed feed, a result associated with greater fiber and lower nitrogen-free extract intake. Mean diurnal levels of rumen volatile fatty acids associated with pelleted rations resulted in an increase in molar percentage rumen acetate and a decrease in butyrate, with little change in propionate or valerate compared to meal rations.Cows fed wheat mixed feed as a meal lost weight; those on other treatments gained weight.Wheat mixed feed, fed in pelleted form, was comparable to barley or a mixed grain ration in meal or pelleted forms as the only concentrate for lactating cows.