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炎热天气下日粮阴阳离子差和日粮粗蛋白对泌乳奶牛生产性能的影响。

Effect of dietary cation-anion difference and dietary crude protein on performance of lactating dairy cows during hot weather.

作者信息

Wildman C D, West J W, Bernard J K

机构信息

Department of Animal and Dairy Science, The University of Georgia, Tifton 31793-0748, USA.

出版信息

J Dairy Sci. 2007 Apr;90(4):1842-50. doi: 10.3168/jds.2006-546.

Abstract

Thirty-two lactating Holstein cows (225 +/- 63 d in milk) were used in a 6-wk trial to determine the effect of dietary cation-anion difference (DCAD) and dietary crude protein (CP) concentration on milk and component yield, acid-base status, and serum AA concentrations during hot weather. Treatments were arranged as a 2 x 2 factorial within a randomized complete block design to provide 15 or 17% CP and a DCAD of 25 or 50 mEq (Na + K - Cl)/100 g of dry matter (DM). A DCAD x CP interaction was detected for milk yield; milk yield was less for high DCAD than for low DCAD for the high-CP diets. No differences were noted at low dietary CP. Milk fat percentage was greater for high DCAD than for low DCAD, and high-CP diets supported greater milk fat percentage than low-CP diets. No differences were observed among treatments for dry matter intake or milk protein percentage. Serum total AA and essential AA concentrations and ratio of essential AA:total AA were greater for high DCAD. These results suggest that increasing DCAD improves AA availability for protein synthesis by taking the place of AA that would otherwise be used for maintenance of acid-base balance. A better understanding of the mechanisms behind this AA-sparing effect will improve management of protein nutrition in the lactating dairy cow.

摘要

选用32头处于泌乳期的荷斯坦奶牛(产奶225±63天),进行为期6周的试验,以确定炎热天气下日粮阴阳离子差(DCAD)和日粮粗蛋白(CP)浓度对牛奶及乳成分产量、酸碱状态和血清氨基酸浓度的影响。试验处理按2×2析因设计,随机完全区组排列,设置15%或17%的CP水平以及25或50 mEq(Na + K - Cl)/100 g干物质(DM)的DCAD水平。检测到DCAD×CP对产奶量存在交互作用;高CP日粮中,高DCAD组的产奶量低于低DCAD组。低日粮CP水平下未观察到差异。高DCAD组的乳脂率高于低DCAD组,且高CP日粮组的乳脂率高于低CP日粮组。各处理间在干物质采食量或乳蛋白率方面未观察到差异。高DCAD组的血清总氨基酸、必需氨基酸浓度以及必需氨基酸与总氨基酸的比例更高。这些结果表明,提高DCAD可通过替代原本用于维持酸碱平衡的氨基酸来提高蛋白质合成中氨基酸的利用率。更好地理解这种氨基酸节约效应背后的机制将有助于改善泌乳奶牛蛋白质营养的管理。

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