Leonardi C, Giannico F, Armentano L E
Department of Dairy Science, University of Wisconsin-Madison, Madison, WI 53706, USA.
J Dairy Sci. 2005 Mar;88(3):1043-9. doi: 10.3168/jds.S0022-0302(05)72772-7.
The objective of this study was to determine whether adding water to a dry diet would reduce sorting and improve cow performance. Eighteen multiparous lactating Holstein cows were used in a cross-over design with 21-d periods. Treatments had the same dietary composition and differed only by adding water (WET) or not (DRY). Diets consisted of 10% alfalfa silage, 30% hay (approximately 80% grass and 20% alfalfa), and 60% concentrate [dry matter (DM) basis]. Dietary DM was 80.8% for DRY and 64.4% for WET. Both diets contained 16.9% crude protein and 24.3% neutral detergent fiber. Particle size was determined using the Wisconsin Particle Size Separator on the as-fed diets. The separator has five square-hole screens (Y(1) to Y(5)) with diagonal openings of 26.9 mm for Y(1), 18 mm for Y(2), 8.98 mm for Y(3), 5.61 mm for Y(4), and 1.65 mm for Y(5), and one pan. Sorting was calculated on a 60 degrees C DM basis (60DM). Predicted intake of Y(i) was calculated as the product of 60DM intake (60DMI) and the 60DM fraction of Y(i) in the total mixed ration for that screen. For DRY and WET, actual 60DMI by screen expressed as a percentage of predicted intake was 61.4% vs. 75.2% for Y(1), 83.8% vs. 98.6% for Y(2), 85.6% vs. 90.8% for Y(3), 95.2% vs. 96.0% for Y(4), 100.1% vs. 101.9% for Y(5), and 105.9% vs. 102.9% for pan, respectively. Adding water did not affect total DM intake (28.3 kg/d) or milk production (41.3 kg/d). Neutral detergent fiber intake was 6.42 kg/d for WET and 6.15 kg/d for DRY. Milk fat percentage tended to be higher (3.41% vs. 3.31%) when cows consumed WET vs. DRY. No differences in ruminal pH, NH(3), and volatile fatty acids were observed. Cows sorted against long particles in favor of shorter particles on both diets. Adding water to dry diets reduced sorting and tended to increase neutral detergent fiber intake and milk fat percentage.
本研究的目的是确定向干饲料中添加水是否会减少挑食现象并提高奶牛的生产性能。18头经产泌乳荷斯坦奶牛用于采用21天周期的交叉设计。各处理的日粮组成相同，仅在是否添加水（湿饲）方面有所不同（干饲）。日粮由10%的苜蓿青贮、30%的干草（约80%的禾本科牧草和20%的苜蓿）以及60%的精料组成（以干物质计）。干饲日粮的干物质含量为80.8%，湿饲日粮为64.4%。两种日粮均含有16.9%的粗蛋白和24.3%的中性洗涤纤维。使用威斯康星粒度分离器对饲喂状态下的日粮测定粒度。该分离器有五个方孔筛网（Y(1)至Y(5)），Y(1)的对角线开口为26.9毫米，Y(2)为18毫米，Y(3)为8.98毫米，Y(4)为5.61毫米，Y(5)为1.65毫米，还有一个底盘。挑食情况以60℃干物质为基础（60DM）进行计算。Y(i)的预测采食量计算为60DM采食量（60DMI）与该筛网在总混合日粮中Y(i)的60DM比例的乘积。对于干饲和湿饲，各筛网实际的60DMI占预测采食量的百分比，Y(1)分别为61.4%对75.2%，Y(2)为83.8%对98.6%，Y(3)为85.6%对90.8%，Y(4)为95.2%对96.0%，Y(5)为100.1%对101.9%，底盘为105.9%对102.9%。添加水不影响总干物质采食量（28.3千克/天）或产奶量（41.3千克/天）。湿饲的中性洗涤纤维采食量为6.42千克/天，干饲为6.15千克/天。奶牛采食湿饲时乳脂率往往更高（3.41%对3.31%）。瘤胃液pH值、氨和挥发性脂肪酸未观察到差异。两种日粮下奶牛均会挑选较短颗粒而不选长颗粒。向干饲料中添加水可减少挑食现象，并往往会增加中性洗涤纤维采食量和乳脂率。
