Maximal Replacement of Forage and Concentrate with a New Wet Corn Milling Product for Lactating Dairy Cows

摘要

Three experiments were conducted to determine the maximal amount of concentrate and forage that could be replaced with a new wet corn milling product. The corn milling product contained 23.1/100 crude protein, 9.9/100 ruminally undegradable protein, 13.7/100 acid deter- gent fiber, 40.3/100 neutral detergent fiber, and 2.6/100 ether extract (/100 of dry matter, DM). In experiment 1, 16 Hol- stein cows were assigned to one of four diets in a repli- cated 4 x 4 Latin square design with 28-d periods. The fOur diets contained 54.3/100 forage (alfalfa:corn silages, 1t1 DM basis) with the wet corn milling product replac- ing 0, 50, 75, or 100/100 of the concentrate portion (corn and soybean meal) of the diet (DM basis). The diets containing wet corn milling product resulted in 7.8/100 lower DM intake, equivalent milk production (28.5 kg/ d), and 13.6/100 greater efficiency of 4/100 fat-corrected milk (FCM) production than the control diet. There was no effect of diet on ruminal pH. In experiment 2, 16 Holstein cows were assigned to one of four diets in a replicated 4 x 4 Latin square design with 28-d periods. The 100/100 concentrate replacement diet from experiment 1 was used as control diet. For the test diets, forage was re- placed with 15, 30, or 45/100 of the corn milling product (DM basis). Efficiency of FCM production (1.16) was not affected by diet. Rumination time was reduced for the 30 and 45/100 forage replacement diets, but ruminal pH was unaffected. In experiment 3, 30 Holstein cows were assigned at parturition to either a control diet (no corn milling product) or a diet containing 40/100 corn milling feed in place of both forage and concentrate (optimal levels from experiments 1 and 2) for 9 wk. The diet containing corn milling feed resulted in 21/100 greater effi- ciency of FCM production than the control diet. These results indicate that a new feed product based on wet corn milling ingredients has the potential to effectively replace all of the concentrate and up to 45/100 of the forage in the diet for lactating dairy cows.