Lactational performance of Holstein dairy cows fed 3 concentrations of full-fat corn dried distillers grains with solubles

Our objective was to evaluate production performance of lactating Holstein dairy cows fed 3 different dietary concentrations of full-fat dried distillers grains with solubles (DDGS; 13.6% fat, DM basis). Thirty cows were fed 0, 10, and 20% DDGS DM as a TMR in a 3 × 3 crossover. Cows were stratified into groups of 10 by parity and DIM and fed each of 3 diets in three 28-d periods. Based on our prior research, we hypothesized that feeding 20% DDGS (DM basis) would negatively influence production and feed efficiency of dairy cattle. Effect of DDGS on DMI was inconsistent; the control and 20% DDGS diets were equivalent and the DMI of cows fed 10% DDGS was lower than both. Milk yield was not affected by treatment, but there was a linear depression in milk fat percentage, milk yield, and yield of 3.5% FCM and energy-corrected milk (ECM) with increasing DDGS in the diet. Both protein and lactose percentages increased when cows were fed DDGS; neither protein nor lactose yield, however, was affected. Protein efficiency, a measure of the use of dietary protein for milk protein synthesis, decreased for cows fed 20% DDGS, possibly resulting from differing amounts of metabolizable lysine. All 3 measures of energetic efficiency [ECM/DMI, kg of ECM/NEl intake (Mcal), and GE of milk produced (Mcal)/NEl caloric intake (Mcal)] decreased when cows were fed 20% DDGS but not when cows were fed 10% DDGS. These results indicate that, with the exception of an approximate loss of milk fat by 0.5 percentage points, full-fat DDGS used in this study can be effectively fed at 10% without a loss in production performance when compared with a control diet not containing DDGS. Feeding the full-fat DDGS at 20%, however, is not advisable.