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Holstein dairy cows with high phosphorus utilization efficiency fed a low phosphorous diet secreted less phosphorus with urine but more with milk and feces
Science of the Total Environment ( IF 9.8 ) Pub Date : 2021-05-17 , DOI: 10.1016/j.scitotenv.2021.147813
Carolin Beatrix Maria Müller 1 , Björn Kuhla 1
Affiliation  

The environmental pollution of phosphorus (P) from livestock farming is becoming increasingly problematic especially with regard to dwindling global P resources. Thus, a more sustainable handling of P resources, including improvements in P use efficiency and a reduction of P loss from farm animals, is necessary. Dairy cows may differ in milk P yield and P use efficiency despite receiving the same feed ration. The objective of this study was to elucidate inter-individual differences in P and closely linked nitrogen (N) excretions and the expression of P transport proteins in dairy cows with low and high P utilization efficiency. Twenty multiparous, late lactating German Holstein dairy cows were retrospectively assigned to either a high (HPeff; n = 10) or low (LPeff; n = 10) P utilization efficiency group. Cows were fed a diet low in P and crude protein (CP) content. During a 4-day balance study, feed intake, urine and fecal excretions, and milk yield were recorded to determine total P and N content in subsamples. Mammary gland, kidney and jejunal mucosa were sampled to analyze mRNA expressions of P transporters by real-time-PCR. A high milk P yield in HPeff cows strongly correlated with milk protein and milk N yield. HPeff cows excreted less urinary P, had a higher renal P reabsorption rate, and a higher renal sodium-P cotransporter 2 expression than LPeff cows. As HPeff cows channeled more P into milk, they mobilized more P from body reserves as indicated by their more negative P-balance. In addition, HPeff cows had higher fecal P excretion relative to ingested P, resulting in a lower apparent P digestibility. In conclusion, when fed a low P diet, HPeff cows channeled more endogenous P into milk and feces, which in the long-term, likely has adverse effects on animal health and the environment.



中文翻译:

用低磷饮食喂养高磷利用率的荷斯坦奶牛,尿液中磷的分泌较少,牛奶和粪便中磷的分泌更多

畜牧业对磷(P)的环境污染正变得越来越成问题,特别是在全球磷资源减少的情况下。因此,有必要对磷资源进行更可持续的处理,包括提高磷的利用效率和减少牲畜磷的损失。尽管饲喂量相同,但奶牛的磷产量和磷利用效率可能会有所不同。本研究的目的是阐明低磷和高磷利用效率的奶牛中磷和紧密相连的氮(N)排泄物的个体间差异以及磷转运蛋白的表达。回顾性地将20头产多,晚期泌乳的德国荷斯坦奶牛分配为高(HPeff; n = 10)或低(LPeff; n= 10)磷利用效率组。母牛饲喂的磷和粗蛋白(CP)含量低。在为期4天的平衡研究中,记录了采食量,尿液和粪便排泄物以及牛奶产量,以确定子样品中的总磷和氮含量。采样乳腺,肾脏和空肠黏膜,通过实时荧光定量PCR分析P转运蛋白的mRNA表达。HPeff奶牛的高P奶产量与牛奶蛋白和N奶产量密切相关。与LPeff奶牛相比,HPeff奶牛排泄的尿P少,肾P重吸收率更高,并且肾钠P共转运蛋白2表达更高。随着HPeff奶牛将更多的P引入牛奶中,他们从体内的储备中调动了更多的P,这是因为它们的负P平衡更弱。此外,相对于摄入的P,HPeff牛的粪便P排泄量更高,导致表观P消化率较低。

更新日期:2021-05-22
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