Pereira A B D, Whitehouse N L, Aragona K M, Schwab C S, Reis S F, Brito A F
Department of Agriculture, Nutrition, and Food Systems, University of New Hampshire, Durham 03824.
Schwab Consulting LLC, Boscobel, WI 53805.
J Dairy Sci. 2017 Aug;100(8):6239-6255. doi: 10.3168/jds.2016-12140. Epub 2017 Jun 7.
Previous research has shown that cows fed ≥24% of the diet dry matter (DM) as field peas decreased milk yield as well as concentration and yield of milk protein, possibly due to reduced DM intake and limited supply of Lys and Met. Twelve multiparous and 4 primiparous lactating Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design. The diets contained (DM basis) 34.8% corn silage, 15.2% grass-legume silage, 5.9% roasted soybean, 2.4% mineral-vitamin premix, 2.0% alfalfa pellets, and either (1) 36% ground corn, 2.4% soybean meal, and 1.3% urea (UR), (2) 29.7% ground corn, 9.8% soybean meal, 0.13% ruminally protected (RP) Lys, and 0.07% RP-Met (CSBAA), (3) 25% ground field peas, 12.3% ground corn, and 2.4% soybean meal (FP), or (4) FP supplemented with 0.15% RP-Lys and 0.05% RP-Met (FPAA). Our objective was to test the effects of FP versus UR, FPAA versus CSBAA, and FPAA versus FP on milk yield and composition, N utilization, nutrient digestibility, ruminal fermentation profile, and plasma concentration of AA. Milk yield did not differ across diets. Compared with cows fed UR, those fed FP had greater DM intake, concentration and yield of milk true protein, apparent total-tract digestibility of fiber, urinary excretion of purine derivatives, and concentrations of total volatile fatty acids in the rumen and Lys in plasma, and less milk urea N and ruminal NH-N. The concentration of milk urea N, as well as the concentration and yield of milk fat increased in cows fed FPAA versus CSBAA. Moreover, cows fed FPAA had greater ruminal concentration of total volatile fatty acids, increased proportions of acetate and isobutyrate, and decreased proportions of propionate and valerate than those fed CSBAA. The plasma concentrations of His, Leu, and Phe decreased, whereas plasma Met increased and plasma Lys tended to increase in cows fed FPAA versus CSBAA. Concentration of milk true protein, but not yield, was increased in cows fed FPAA versus FP. However, cows fed FPAA showed decreased concentrations of His and Leu in plasma compared with those fed FP. Overall, compared with the CSBAA diet, feeding FPAA did not negatively affect milk yield and milk protein synthesis. Furthermore, RP-Lys and RP-Met supplementation of the FP diet did not improve milk yield or milk protein synthesis, but decreased urinary urea N excretion.
先前的研究表明，日粮干物质（DM）中豌豆含量≥24%的奶牛，其产奶量以及乳蛋白浓度和产量会降低，这可能是由于干物质摄入量减少以及赖氨酸（Lys）和蛋氨酸（Met）供应有限所致。将12头经产和4头初产泌乳荷斯坦奶牛随机分配到4种日粮中的1种，采用重复4×4拉丁方设计。日粮（以DM计）包含34.8%的玉米青贮、15.2%的禾本科-豆科青贮、5.9%的烤大豆、2.4%的矿物质-维生素预混料、2.0%的苜蓿颗粒，以及以下几种情况之一：（1）36%的玉米粉、2.4%的豆粕和1.3%的尿素（UR）；（2）29.7%的玉米粉、9.8%的豆粕、0.13%的瘤胃保护（RP）赖氨酸和0.07%的RP-蛋氨酸（CSBAA）；（3）25%的豌豆粉、12.3%的玉米粉和2.4%的豆粕（FP）；或（4）添加0.15% RP-赖氨酸和0.05% RP-蛋氨酸的FP（FPAA）。我们的目标是测试FP与UR、FPAA与CSBAA、FPAA与FP对产奶量和组成、氮利用、养分消化率、瘤胃发酵概况以及血浆氨基酸浓度的影响。不同日粮间的产奶量没有差异。与饲喂UR的奶牛相比，饲喂FP的奶牛干物质摄入量更高，乳真蛋白浓度和产量、纤维表观全肠道消化率、嘌呤衍生物尿排泄量、瘤胃总挥发性脂肪酸浓度以及血浆中赖氨酸浓度更高，乳尿素氮和瘤胃氨氮更少。与饲喂CSBAA的奶牛相比，饲喂FPAA的奶牛乳尿素氮浓度以及乳脂肪浓度和产量增加。此外，与饲喂CSBAA的奶牛相比，饲喂FPAA的奶牛瘤胃总挥发性脂肪酸浓度更高，乙酸和异丁酸比例增加，丙酸和戊酸比例降低。与饲喂CSBAA的奶牛相比，饲喂FPAA的奶牛血浆中组氨酸（His）、亮氨酸（Leu）和苯丙氨酸（Phe）浓度降低，而血浆蛋氨酸增加，血浆赖氨酸有增加趋势。与饲喂FP的奶牛相比，饲喂FPAA的奶牛乳真蛋白浓度增加，但产量未增加。然而，与饲喂FP的奶牛相比，饲喂FPAA的奶牛血浆中His和Leu浓度降低。总体而言，与CSBAA日粮相比，饲喂FPAA对产奶量和乳蛋白合成没有负面影响。此外，在FP日粮中添加RP-赖氨酸和RP-蛋氨酸并没有提高产奶量或乳蛋白合成，但降低了尿尿素氮排泄量。
