Lactation performance, nitrogen utilization, and profitability in dairy cows fed fermented total mixed ration containing wet corn gluten feed and corn stover in combination replacing a portion of alfalfa hay

摘要

To effectively use corn by-products for ruminants, lactation performance, nitrogen utilization, and profitability in lactating dairy cows fed fermented total mixed ration (FTMR) that contained wet corn gluten feed (WCGF) and corn stover in combination replacing a portion of alfalfa hay were studied. Thirty-six multiparous Holstein dairy cows (602 +/- 46.8 kg of body weight; 109 +/- 18.5 day in milk; 30.1 +/- 1.53 kg of milk production; and 2.44 +/- 0. 51 of parity; mean +/- SD) were blocked into 12 groups based on DIM, milk production, and parity and were allocated randomly to 1 of 3 diets for a 14-week period, with the first 2 weeks allowed for adaptation to the diets. The TMR was prepared with same mixed ration of concentrate mixtures and corn silage but different proportions of alfalfa hay, corn stover and WCGF. The treatments were designed as (1) TMR A containing 220 g/kg DM alfalfa hay; (2) TMR B containing 118 g/kg DM alfalfa hay, 68.8 g/kg DM WCGF, and 34.4 g/kg DM corn stover; and (3) Fermented TMR (FTMR) prepared with same ingredient as TMR B. The FTMR diet had higher crude protein (CP) and lactic acid contents content, the ratio of ammonia nitrogen to total N while decreased pH value, neutral detergent fiber (NDF), acid detergent fiber (ADF) and dry matter (DM) content compared to other two diets. The milk fat concentration, milk fat yield, DM and CP degradation, estimated microbial CP yield and feed efficiency were higher (P < 0.05) in the cows fed FTMR treatment but DM intake was lower (P < 0.05) in the cows fed the FTMR treatment than the cows fed the other treatments. The concentrations of rumen volatile fatty acids, except for butyrate, were highest (P < 0.0001) in cows fed the FTMR diet followed by cows fed TMR B and TMR A diets. The cows fed the FTMR diet had a higher molar proportion of acetate, total-tract apparent digestibility and ammonia-N concentration and a lower molar proportion of butyrate, organic matter, NDF, and ADF intakes than the cows fed the other diets. The cows fed the FTMR diet decreased fecal N excretion and retention N, increased the urea nitrogen concentration in the urine and milk and improved income over feed cost per cow per day compared with the cows fed the other diets. The results confirmed that FTMR prepared with WCGF and corn stover in combination replacing a portion of alfalfa hay is a suitable choice for improving lactation performance of dairy cows.