Crop processing and chop length of corn silage: Effects on intake, digestion, and milk production by dairy cows

Effects of corn silage crop processing and chop length on intake, digestion , and milk production were evaluated. Corn silage treatments were harvested at one-half milkline stage of maturity (65% whole-plant moisture content) and at 0.95-cm theoretical length of cut without processing (control) or 0. 95-, 1.45-, or 1.90-cm theoretical length of cut with processing at a l-mm roll clearance. Twenty-four multiparous Holstein cows averaging 71 d in mil k at trial initiation were in a replicated 4 x 4 Latin square design with 2 8-d periods; one square was comprised of ruminally cannulated cows for rume n measurements. Corn silage treatments were fed in total mixed rations cont aining 50% forage (67% corn silage and 33% alfalfa silage) and 50% corn and soybean meal based concentrate (dry matter basis). Dry matter intake (25.9 vs. 25.3 kg/d) and milk (46.0 vs. 44.8 kg/d) and fat (1.42 vs. 1.35 kg/d) yields mere higher for the processed corn silage treatments compared with t he control corn silage. Within the processed corn silage treatments, there were no chop length effects on intake, milk production, or milk composition . Chewing activity was not different among the four corn silage treatments averaging 12 h/d. Total tract digestion of dietary starch was lower for con trol corn silage (95.1%) compared with fine, medium, and coarse processed c orn silage treatments, which averaged 99.3%. Total tract digestion of dieta ry NDF was reduced for fine-processed corn silage compared with control cor n silage and coarse-processed corn silage (28.4% vs. 33.9 and 33.7%, respec tively). Processing corn silage improved dry matter intake, starch digestio n, and lactation performance. Under the conditions of this study and with t heoretical lengths of cut ranging from 0.95 to 1.90 cm, length of chop effe cts were minimal in processed corn silage.