The role of rumen epithelial urea transport proteins in urea nitrogen salvage: A review

Zhong, Chongliang; Long, Ruijun; Stewart, Gavin

doi:10.1016/j.aninu.2022.01.008

Cited by 6 publications

(1 citation statement)

References 89 publications

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“…In addition, ruminal UT-B and AQP3 expressions are upregulated when calves are transferred from milk replacer to solid feed feeding 53 , as well as in cows receiving a diet formulated for the pre-partum compared to post-partum requirements 55 . Overall, it seems that the regulation of the ruminal urea transporters is mainly due to dietary fermentable carbohydrates affecting ruminal conditions, such as pH, CO 2 , and short-chain fatty acid concentration 56 , but not controlled by plasma urea or dietary CP concentrations.…”

Section: Discussionmentioning

confidence: 97%

Mammary gland, kidney and rumen urea and uric acid transporters of dairy cows differing in milk urea concentration

Prahl,

Müller,

Wimmers

et al. 2023

Sci Rep

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The milk urea concentration (MUC) serves as indicator of urinary nitrogen emissions, but at comparable crude protein (CP) intake, cows with high (HMU) and low (LMU) MUC excrete equal urea amounts. We hypothesized that urea and uric acid transporters and sizes of the kidney, mammary gland, and rumen account for these phenotypes. Eighteen HMU and 18 LMU Holstein dairy cows fed a low (LP) and normal (NP) CP diet were studied. Milk, plasma and urinary urea concentrations were greater with NP feeding, while plasma and urinary urea concentrations were comparable between phenotypes. Milk and plasma uric acid concentrations were higher with LP feeding but not affected by phenotype. The milk-urine uric acid ratio was greater in HMU cows. The mRNA expressions of the ruminal urea transporter SLC14A1 and AQP10, the mammary gland and rumen AQP3, and the mammary gland uric acid transporter ABCG2 were not affected by group or diet. Renal AQP10, but not AQP3, AQP7, and SLC14A2 expressions, and the kidney weights were lower in HMU cows. These data indicate that renal size and AQP10 limit the urea transfer from blood to urine, and that MUC determines if uric acid is more released with milk or urine.

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Section: Discussionmentioning

confidence: 97%