Vazquez O P, Smith T R
Department of Dairy Science, University of Wisconsin-Madison, 53706, USA.
J Dairy Sci. 2000 Oct;83(10):2301-9. doi: 10.3168/jds.S0022-0302(00)75117-4.
We investigated the most relevant variables for estimating pasture intake and total dry matter (DM) intake in grazing dairy cows using 27 previously published studies. Variables compared were pasture allowance, days in milk, amount of forage, amount of concentrate and total supplementation, pasture allowance and supplementation interaction, fat-corrected milk, body weight (BW), metabolic BW, daily change in BW, percentage of legumes in pasture, neutral detergent fiber (NDF) contents of pasture, and NDF in pasture selected. The variables were selected using stepwise regression analysis for total DM intake and pasture DM intake. Variables selected in the total DM intake regression equation (R2 = 0.95) were pasture allowance, total supplementation, interaction of pasture allowance and supplementation, fat-corrected milk, BW, daily change in BW, percentage of legumes and pasture NDF content. Pasture DM intake regression equation (R2 = 0.90) was similar to total DM intake equation, but supplementation coefficient was negative, showing substitution effect in supplementing grazing cows. The intake of NDF as a percentage of BW was higher than 1.3% when considering NDF content of the pasture allowance. Low pasture allowance groups had values higher than 1.3%.
我们利用27项先前发表的研究，调查了用于估算放牧奶牛牧草摄入量和总干物质（DM）摄入量的最相关变量。比较的变量有牧草供应量、泌乳天数、粗饲料量、精饲料量和总补充量、牧草供应量与补充量的相互作用、脂肪校正乳、体重（BW）、代谢体重、体重日变化、牧草中豆科植物的百分比、牧草的中性洗涤纤维（NDF）含量以及所选牧草中的NDF。这些变量通过对总DM摄入量和牧草DM摄入量进行逐步回归分析来选择。在总DM摄入量回归方程（R2 = 0.95）中选择的变量有牧草供应量、总补充量、牧草供应量与补充量的相互作用、脂肪校正乳、BW、体重日变化、豆科植物百分比和牧草NDF含量。牧草DM摄入量回归方程（R2 = 0.90）与总DM摄入量方程相似，但补充系数为负，表明在补充放牧奶牛时存在替代效应。考虑到牧草供应量的NDF含量时，NDF摄入量占BW的百分比高于1.3%。低牧草供应量组的值高于1.3%。
