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与含玉米酒糟的高蛋白日粮相比,奶牛采食添加瘤胃非降解蛋白和瘤胃保护氨基酸的日粮混合物对产奶性能和氮代谢的影响。

Production performance and nitrogen metabolism in dairy cows fed supplemental blends of rumen undegradable protein and rumen-protected amino acids in low- compared with high-protein diets containing corn distillers grains.

机构信息

Animal, Veterinary, and Food Sciences Department, University of Idaho, Moscow 83844-2330.

H. J. Baker & Bro. LLC, Shelton, CT 06484.

出版信息

J Dairy Sci. 2021 Apr;104(4):4134-4145. doi: 10.3168/jds.2020-19697. Epub 2021 Feb 19.

Abstract

Feeding corn dried distillers grains with solubles (DDGS) in low crude protein (CP) diets could limit N waste in lactating cows. However, it also could possibly reduce metabolizable AA supply, especially Lys, and compromise milk production. Therefore, the objective of this study was to evaluate the effects of feeding supplemental blends of rumen undegradable protein (RUP) and rumen-protected (RP) AA in a low compared with high CP diet containing corn DDGS on milk production and selected measures of N utilization. Six multiparous Holstein cows (619.3 ± 49.8 kg of body weight; 26.8 ± 6.2 d in milk) were subjected to a split-plot, 3 × 3 Latin square design (21-d periods) with dietary CP content [low (14.6%; LP) or high (16.6%; HP)] as the whole-plot factor, and blend of RUP and RP-AA [control (CON), no supplement; blend A (0.11 kg/cow per d); or blend B (0.45 kg/cow per d)] as the sub-plot factor. All diets contained 10% corn DDGS; blends of RUP and RP-AA were top-dressed during morning feeding. There was no dietary CP content × supplemental blend interaction for all measured variables. Nutrient (dry matter, organic matter, neutral detergent fiber, acid detergent fiber, and CP), milk and milk component yields, and feed and apparent N efficiency did not differ for cows fed the low- compared with the high-protein diet. However, apparent total-tract CP digestibility, blood and milk urea-N concentrations, and urinary excretion (g/d) of N and urea-N were lower for cows fed the low-protein compared with the high-protein diet. There was no supplemental blend effect on nutrient intake and apparent total-tract digestibility, and milk and milk component yields. Except for a tendency for total urinary purine derivative excretion and microbial N flow to be lower for cows fed blend B compared with CON but not blend A, there was no supplemental blend effect on measures of N utilization. Both dietary CP content and supplemental blend of RUP and RP-AA had a marginal effect on the plasma free AA profile. In summary, reducing dietary CP content in diets containing corn DDGS had no effect on lactation performance, possibly accounting for the lack of a positive response following the provision of supplemental blends of RUP and RP-AA. However, reducing dietary CP content resulted in a decrease in blood and milk urea-N concentrations, and urinary excretion of N and urea-N, suggestive of an improvement in the efficiency of N use.

摘要

在低粗蛋白(CP)日粮中添加含有可溶物的干酒糟及其可溶物(DDGS)可限制泌乳奶牛的氮浪费。然而,它也可能降低可代谢氨基酸(AA)的供应,特别是赖氨酸,并影响牛奶产量。因此,本研究的目的是评估在低 CP 日粮中添加瘤胃未降解蛋白(RUP)和保护型(RP)AA 混合物与高 CP 日粮相比对产奶量和氮利用的某些指标的影响,该日粮含有玉米 DDGS。6 头经产荷斯坦奶牛(619.3 ± 49.8 kg 体重;泌乳 26.8 ± 6.2 d)采用 3×3 拉丁方设计(21 d 期),日粮 CP 含量(低(14.6%;LP)或高(16.6%;HP))为全部分区因素,RUP 和 RP-AA 混合物(对照(CON),无补充;混合物 A(0.11 kg/奶牛/天);或混合物 B(0.45 kg/奶牛/天))为亚区因素。所有日粮均含有 10%的玉米 DDGS;RUP 和 RP-AA 混合物在早晨喂食时进行顶料添加。对于所有测量变量,均不存在日粮 CP 含量×补充混合物的互作效应。与高蛋白日粮相比,低蛋白日粮对奶牛的养分(干物质、有机物、中性洗涤纤维、酸性洗涤纤维和 CP)、奶和奶成分产量以及饲料和表观氮效率没有影响。然而,与高蛋白日粮相比,低蛋白日粮的奶牛表观总肠道 CP 消化率、血液和牛奶尿素氮浓度以及氮和尿素氮的尿排泄量(g/d)更低。对于奶牛的养分摄入量和总肠道表观消化率以及奶和奶成分产量,补充混合物没有影响。除了奶牛采食混合物 B 时总尿嘌呤衍生物排泄和微生物氮流量趋于较低外,氮利用的其他测量指标均未受补充混合物的影响。日粮 CP 含量和 RUP 和 RP-AA 的补充混合物对血浆游离 AA 谱均有边际影响。总之,在含有玉米 DDGS 的日粮中降低 CP 含量对泌乳性能没有影响,这可能是由于添加 RUP 和 RP-AA 补充混合物后没有产生积极的反应。然而,降低日粮 CP 含量会降低血液和牛奶尿素氮浓度以及氮和尿素氮的尿排泄量,提示氮利用效率的提高。

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