Utilization of Distillers Dried Grains Plus Solubles by Dairy Cows in Early Lactation

A concentrate mix containing 48% distillers dried grains with solubles was compared with isonitrogenous soybean meal-based mixes without (negative control) or with (positive control) supplemental fat in a feeding trial of 24 cows (16 Holsteins, 8 Jerseys) during the first 50 days of lactation. Jerseys fed distillers grains produced more daily fat-corrected milk per unit metabolic body size (.255 versus .196) than negative controls; response of Holsteins was opposite, causing a significant interaction of breed x treatment. Milk protein percent was decreased by distillers grains in both breeds but significantly only in Jerseys. Ratio of acetic/propionic acids in rumen content was higher in cows fed distillers grains than in those fed negative and positive controls (2.68 versus 2.15 and 2.17, respectively). Based on comparative blood amino acid profiles, unavailable protein of distillers grains may have limited milk protein content.