Neal K, Eun J-S, Young A J, Mjoun K, Hall J O
Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan 84322.
Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan 84322.
J Dairy Sci. 2014 Dec;97(12):7716-28. doi: 10.3168/jds.2014-8033. Epub 2014 Sep 26.
Due to the increasing cost of soybean meal and concerns of excess N being excreted into the environment, new protein supplements have been developed. Two products that have shown potential in increasing N utilization efficiency are slow-release urea (SRU; Optigen; Alltech Inc., Nicholasville, KY) and ruminal-escape protein derived from yeast (YMP; DEMP; Alltech Inc.). The objective of this study was to assess the effects of feeding these 2 supplements in alfalfa hay-based [45.7% of forage dietary dry matter (DM)] dairy diets on nutrient utilization, feed efficiency, and lactational performance of dairy cows. Twelve multiparous dairy cows were used in a triple 4 × 4 Latin square design with one square consisting of ruminally cannulated cows. Treatments included (1) control, (2) SRU-supplemented total mixed ration (SRUT), (3) YMP-supplemented total mixed ration (YMPT), and (4) SRU- and YMP-supplemented total mixed ration (SYT). The control consisted only of a mixture of soybean meal and canola meal in a 50:50 ratio. The SRU and the YMP were supplemented at 0.49 and 1.15% DM, respectively. The experiment consisted of 4 periods lasting 28 d each (21 d of adaptation and 7 d of sampling). Cows fed YMPT and SYT had decreased intake of DM, and all supplemented treatments had lower crude protein intake compared with those fed the control. Milk yield tended to have the greatest increase in YMPT compared with the control (41.1 vs. 39.7 kg/d) as well as a tendency for increased milk fat and protein yields. Feed efficiencies based on yields of milk, 3.5% fat-corrected milk, and energy-corrected milk increased at 10 to 16% due to protein supplementation. Cows fed protein supplements partitioned less energy toward body weight gain, but tended to partition more energy toward milk production. Efficiency of use of feed N to milk N increased by feeding SRUT and YMPT, and milk N-to-manure N ratio increased with YMPT. Overall results from this experiment indicate that replacing the mixture of soybean meal and canola meal with SRU and YMP in alfalfa hay-based dairy diets can be a good approach to improve nutrient utilization efficiencies in lactating dairy cows.
由于豆粕成本不断增加以及人们对过量氮排泄到环境中的担忧，已开发出新的蛋白质补充剂。两种在提高氮利用效率方面显示出潜力的产品是缓释尿素（SRU；Optigen；奥特奇公司，肯塔基州尼古拉斯维尔）和源自酵母的瘤胃逸出蛋白（YMP；DEMP；奥特奇公司）。本研究的目的是评估在以苜蓿干草为基础（占饲粮干物质的45.7%）的奶牛日粮中添加这两种补充剂对养分利用、饲料效率和奶牛泌乳性能的影响。12头经产奶牛采用4×4三重复拉丁方设计，其中一个重复由安装了瘤胃瘘管的奶牛组成。处理包括：（1）对照组，（2）添加SRU的全混合日粮（SRUT），（3）添加YMP的全混合日粮（YMPT），以及（4）添加SRU和YMP的全混合日粮（SYT）。对照组仅由豆粕和油菜籽粕按50:50比例混合而成。SRU和YMP分别按占干物质的0.49%和1.15%添加。试验由4个阶段组成，每个阶段持续28天（21天适应期和7天采样期）。饲喂YMPT和SYT的奶牛干物质摄入量降低，与饲喂对照组的奶牛相比，所有添加处理的粗蛋白摄入量均较低。与对照组相比，YMPT组的产奶量增加幅度最大（分别为41.1和39.7千克/天），乳脂和乳蛋白产量也有增加趋势。由于添加了蛋白质，基于牛奶、3.5%乳脂校正奶和能量校正奶产量的饲料效率提高了10%至16%。饲喂蛋白质补充剂的奶牛分配到体重增加的能量减少，但分配到产奶的能量有增加趋势。饲喂SRUT和YMPT可提高饲料氮转化为牛奶氮的效率，YMPT组的牛奶氮与粪便氮比值增加。本试验的总体结果表明，在以苜蓿干草为基础的奶牛日粮中用SRU和YMP替代豆粕和油菜籽粕混合物，可能是提高泌乳奶牛养分利用效率的良好方法。
