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Effect Of Brown Midrib Corn Silage And Dried Distillers Grains Plus Solubles On Lactational Performance And Nitrogen Utilization By Dairy Cows, Hugo A. Ramirez

Department of Animal Science: Dissertations, Theses, and Student Research

Thirty six Holstein cows, four ruminally cannulated, (mean ± SD, 111 ± 35 DIM; 664 ± 76.5 kg BW) were used in replicated 4×4 Latin squares to investigate the effects of brown midrib (bm3) and conventional (DP) corn silages, and the inclusion of dried distillers grains plus solubles (DDGS) on milk production and N utilization. In each 28 d period cows were assigned to one of four treatments: DP plus 0% DDGS (CON); bm3 plus 0% DDGS (BMR); DP corn silage plus 30% DDGS (DP+DG); and bm3 plus 30% DDGS (BMR+DG). Dry matter intake was greater (P < 0.01) for cows consuming bm3 (25.8 VS 24.4 ± 0.47 kg), likewise for DDGS (24.3 and 25.9 ± 0.47 kg/d for 0 and 30%). Compared to DP hybrid, NDFD was higher (P < 0.01) for bm3 (32.5 VS 38.1 ± 1.79%). There was a hybrid × DDGS interaction (P < 0.01) for total concentration of volatile fatty acids (VFA) and rumen pH as the highly digestible treatment BMR+DG resulted in the highest VFA and the lowest pH. Milk yield was not affected by treatment and averaged 30.6 ± 1.09 kg/d. Milk protein yield (MPY) was greater (P < 0.01) for bm3 and DDGS treatments. There was a hybrid by DDGS interaction (P = 0.02) for milk fat yield (MFY) resulting in 1.03, 1.08, 0.84 and 0.78 ± 0.045 kg/d for DP, BMR, DP+DG and BMR+DG. Fat corrected milk (FCM) was affected by DDGS (P < 0.01) and averaged 30.0 and 26.4 ± 1.0kg/d (0% and 30% inclusions). Urinary N excretion was similar among treatments; however fecal N was lower (P = 0.03) for diets containing bm3 corn silage which caused lower (P = 0.02) manure N. These results indicate that bm3 corn silage and DDGS increase DMI, NDFD and MPY; however high inclusion of corn silage with 30% DDGS reduces FCM. Nitrogen excretion was reduced when cows consumed bm3.