Dairy Science Department, South Dakota State University, Brookings 57007, USA.
J Dairy Sci. 2010 Jan;93(1):288-303. doi: 10.3168/jds.2009-2377.
The use of a solvent-extraction process that removes corn oil from distillers grains produces a reduced-fat co-product (RFDG). To determine the optimal concentration of RFDG in mid-lactation diets, 22 multiparous and 19 primiparous Holstein cows were used in a completely randomized design for 8 wk, including a 2-wk covariate period. The RFDG was included at 0, 10, 20, and 30% of the diet on a dry matter basis, replacing soybean feedstuffs. Increasing RFDG in diets had no effect on dry matter intake (23.1 kg/d) or milk production (35.0 kg/d). Milk fat percentage increased linearly from 3.18 to 3.72% as RFDG increased from 0 to 30% of the diet. Similarly, milk fat yield tended to increase linearly from 1.08 to 1.32 kg/d. Milk protein percentage (2.99, 3.06, 3.13, and 2.99% for diets with RFDG from 0 to 30%) responded quadratically, whereas protein yield was not affected by treatment. Milk urea N decreased linearly from 15.8 to 13.1mg/dL. The efficiency of N utilization for milk production was not affected by including RFDG (26.1%), whereas the efficiency of milk production (energy-corrected milk divided by dry matter intake) tended to increase linearly with increasing RFDG in the diet. Similarly, concentrations of plasma glucose increased linearly. Arterial Lys decreased linearly from 66.0 to 44.8 microM/L, whereas arterial Met increased linearly from 16.5 to 29.3 microM/L. Arteriovenous difference of Lys decreased linearly from 42.6 to 32.5 microM/L, whereas that of Met was unaffected. The extraction of Lys by the mammary gland increased linearly from 64.3 to 72.2%, whereas that of Met decreased linearly from 71.6 to 42.7%. Feeding up to 30% of RFDG in a mid-lactation diet supported lactation performance similarly to cows fed the soybean protein-based diet (0% RFDG).
使用溶剂萃取工艺从酒糟中提取玉米油会产生一种低脂副产物（RFDG）。为了确定中乳期日粮中 RFDG 的最佳浓度，22 头经产和 19 头初产荷斯坦奶牛在完全随机设计下进行了 8 周的试验，包括 2 周协变量期。RFDG 以干物质为基础，分别占日粮的 0、10、20 和 30%，替代豆科饲料。日粮中 RFDG 的增加对干物质采食量（23.1kg/d）或产奶量（35.0kg/d）没有影响。随着日粮中 RFDG 从 0 增加到 30%，牛奶脂肪百分比从 3.18%线性增加到 3.72%。类似地，牛奶脂肪产量也从 1.08kg/d 线性增加到 1.32kg/d。牛奶蛋白百分比（日粮中 RFDG 从 0 增加到 30%时分别为 2.99、3.06、3.13 和 2.99%）呈二次反应，而蛋白产量不受处理影响。牛奶尿素氮（MUN）从 15.8mg/dL 线性下降到 13.1mg/dL。包括 RFDG（26.1%）对牛奶生产的氮利用效率没有影响，而牛奶生产效率（校正能量后的牛奶产量除以干物质采食量）随着日粮中 RFDG 的增加呈线性增加。同样，血浆葡萄糖浓度也呈线性增加。动脉赖氨酸（Lys）从 66.0 微摩尔/升线性下降到 44.8 微摩尔/升，而动脉甲硫氨酸（Met）从 16.5 微摩尔/升线性增加到 29.3 微摩尔/升。乳糜静脉 Lys 差值从 42.6 微摩尔/升线性下降到 32.5 微摩尔/升，而 Met 差值不受影响。乳腺对 Lys 的提取量从 64.3%线性增加到 72.2%，而 Met 的提取量从 71.6%线性下降到 42.7%。在中乳期日粮中添加高达 30%的 RFDG 对泌乳性能的支持与饲喂基于大豆蛋白的日粮（0%RFDG）的奶牛相似。
