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首页> 外文会议>EAAP International Symposium on Energy and Protein Metabolism >Effects of oscillating dietary crude protein concentration on production, nutrient digestibility and nitrogen metabolism in lactating dairy cows
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Effects of oscillating dietary crude protein concentration on production, nutrient digestibility and nitrogen metabolism in lactating dairy cows

机译：辐射膳食粗蛋白浓度对哺乳酸奶牛生产，营养消化率和氮代谢的影响

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Our objective was to determine whether milk production, nutrient digestibility and N metabolism in dairy cows were altered when oscillating the crude protein (CP) content of a diet marginally deficient in metabolizable protein compared to feeding static CP content. In a randomized block design, 30 mid-lactation Holsteins were fed 1 of 3 diets: adequate CP fed continuously (CP+; 16.2% CP); marginally deficient CP fed continuously (CP-; 14.1% CP); or 24-h oscillations from adequate (16.2% CP) to deficient CP (11.9% CP) to be on average equal to CP- (OSC). Total output of urine and feces was used to measure nutrient digestion and balance on 24 cows. Compared to CP-, intake was lower for OSC but similar to CP+. However, milk yield for CP- was less thanCP+ and similar to OSC. Milk protein yield was similar among diets. Milk urea-N was higher for CP+ and tended to be higher for OSC than CP-. Cyclical patterns in milk production were found when oscillating CP and suggested production lags one day to changes in dietary CP. Diet had minimal effects on nutrient digestibility except for CP which was lower for CP- than CP+ and OSC. However, less of the N digested was partitioned into urine for CP- than CP+ and OSC, and less N tended to be retained for OSC. Overall, oscillating CP may improve N utilization through greater CP digestibility and enhanced urea recycling, but additional nutrients may be needed to compensate for reduced intake, enhance milk production and reduce urinary N.
机译：我们的目的是在与饲料静态CP含量相比，在饲料效果略微缺乏饮食的粗蛋白（CP）含量时，改变乳制品的牛奶生产，营养消化率和N代谢。在随机块设计中，喂养30个中哺乳期Holsteins的3个饮食：连续喂养的足够CP（CP +; 16.2％CP）;勉强缺乏CP持续（CP-; 14.1％CP）;或24-H振荡从足够的（16.2％CP）到缺陷CP（11.9％CP）平均等于CP-（OSC）。尿液和粪便的总产量用于测量24奶牛的营养消化和平衡。与CP-相比，OSC的摄入量较低，但类似于CP +。但是，CP-牛奶产量少于+，类似于OSC。饮食中牛奶蛋白质产量相似。 CP +的牛奶尿素-N更高，往往比CP-往往更高。当振荡CP时发现牛奶生产中的循环模式并有一天延迟延迟饮食CP的变化。除CP-CP +和OSC的CP除外，饮食对营养消化率的影响很小。然而，将少量消化较少被分配给尿液以与Cp +和OSC分配，并且较少的N倾向于保留OSC。总体而言，通过更大的CP消化率和增强的尿素回收率可以提高振荡CP可以改善n利用，但可能需要额外的营养素来补偿减少的摄入量，增强牛奶生产和减少尿液。

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