Oba M, Allen M S
Department of Animal Science, Michigan State University, East Lansing 48824-1225, USA.
J Dairy Sci. 1999 Jan;82(1):135-42. doi: 10.3168/jds.S0022-0302(99)75217-3.
The effects of enhanced in vitro neutral detergent fiber (NDF) digestibility of corn silage on dry matter intake (DMI) and milk yield were evaluated using 32 Holstein cows in a crossover design with 28-d periods. At the beginning of the experiment, cows were 89 d in milk and yielded 45.6 kg/d of milk. Experimental diets contained either brown midrib (bm3) corn silage or isogenic normal corn silage (control) at 44.6% of DM. The NDF digestibility estimated by 30-h in vitro fermentation was higher for bm3 corn silage by 9.7 units. Contents of NDF and lignin were lower for bm3 corn silage by 1.8 and 0.8 units, respectively. Diets were formulated to contain 19% crude protein and 31% NDF and to have a forage to concentrate ratio of 56:44. Daily DMI, milk yield (3.5% fat-corrected milk), and solids-corrected milk were 2.1, 2.6, and 2.7 kg higher, respectively, for cows fed bm3 corn silage. The milk protein and lactose contents were greater for bm3 treatment, but milk fat content was not. Individual milk yield responses of the cows to bm3 treatment were positively related to pretrial milk yield, and DMI response tended to be positively related to pretrial milk yield. Enhanced in vitro NDF digestibility was associated with higher energy intake, which resulted in increased milk yield.
采用交叉设计，以32头荷斯坦奶牛为试验对象，进行为期28天的试验期，评估提高玉米青贮体外中性洗涤纤维（NDF）消化率对干物质采食量（DMI）和产奶量的影响。试验开始时，奶牛处于泌乳89天，日产奶量为45.6千克。试验日粮中，干物质的44.6%为棕色中脉（bm3）玉米青贮或同基因正常玉米青贮（对照）。通过30小时体外发酵估算，bm3玉米青贮的NDF消化率高9.7个单位。bm3玉米青贮的NDF和木质素含量分别低1.8和0.8个单位。日粮配方含19%粗蛋白和31%NDF，饲草与精料比为56:44。饲喂bm3玉米青贮的奶牛，日DMI、产奶量（3.5%乳脂校正乳）和固形物校正乳分别高2.1、2.6和2.7千克。bm3处理组的乳蛋白和乳糖含量较高，但乳脂含量无差异。奶牛对bm3处理的个体产奶量反应与试验前产奶量呈正相关，DMI反应也倾向于与试验前产奶量呈正相关。体外NDF消化率提高与能量摄入量增加有关，从而导致产奶量增加。
