Renal Phosphate Excretion in Goats

Widiyono, Irkham; Huber, Korinna; Failing, Klaus; Breves, Gerhard

doi:10.1111/j.1439-0442.1998.tb00810.x

Cited by 14 publications

(9 citation statements)

References 29 publications

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“…During normophosphataemia, about 98% to 99% of filtered P i is resorbed in the kidneys of ruminant species (Widiyono et al, 1998). The mean plasma threshold for renal P i excretion in goats lies around 4.3 mM (Widiyono et al, 1998). Filtered P i is reabsorbed mainly by the proximal tubule cells.…”

Section: Renal Handling Of Phosphorusmentioning

confidence: 99%

Review: Regulation of gastrointestinal and renal transport of calcium and phosphorus in ruminants

Wilkens¹,

Muscher-Banse²

2020

Animal

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In comparison to monogastric animals, ruminants show some peculiarities in respect to the regulation of mineral homeostasis, which can be regarded as a concerted interplay between gastrointestinal absorption, renal excretion and bone mobilisation to maintain physiological Ca and phosphate (Pi) concentrations in serum. Intestinal absorption of Ca or Pi is mediated by two general mechanisms: paracellular, passive transport dominates when luminal Ca or Pi concentrations are high and transcellular. The contribution of active transport becomes more important when dietary Ca or Pi supply is restricted or the demand increased. Both pathways are modulated directly by dietary interventions, influenced by age and regulated by endocrine factors such as 1,25-dihydroxyvitamin D3. Similar transport processes are observed in the kidney. After filtration, Ca and Pi are resorbed along the nephron. However, as urinary Ca and Pi excretion is very low in ruminants, the regulation of these renal pathways differs from that described for monogastric species, too. Furthermore, salivary secretion, as part of endogenous Pi recycling, and bone mobilisation participate in the maintenance of Ca and Pi homeostasis in ruminants. Saliva contains large amounts of Pi for buffering rumen pH and to ensure optimal conditions for the rumen microbiome. The skeleton is a major reservoir of Ca and Pi to compensate for discrepancies between demand and uptake. But alterations of the regulation of mineral homeostasis induced by other dietary factors such as a low protein diet were observed in growing ruminants. In addition, metabolic changes, for example, at the onset of lactation have pronounced effects on gastrointestinal mineral transport processes in some ruminant species. As disturbances of mineral homeostasis do not only increase the risk of the animals to develop other diseases, but are also associated with protein and energy metabolism, further research is needed to improve our knowledge of its complex regulation.

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Section: Renal Handling Of Phosphorusmentioning

confidence: 99%

Review: Regulation of gastrointestinal and renal transport of calcium and phosphorus in ruminants

Wilkens¹,

Muscher-Banse²

2020

Animal

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“…The calcitriol assay had a detection limit of 2 pg/ml. Both calcidiol and calcitriol assays had been used before to determine respective hormone concentrations in goats (10,17,30) .…”

Section: Biochemical Determinationsmentioning

confidence: 99%

Modulation of intestinal calcium and phosphate transport in young goats fed a nitrogen- and/or calcium-reduced diet

Elfers¹,

Wilkens²,

Breves³

et al. 2015

Br J Nutr

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Feeding ruminants a reduced N diet is a common approach to reduce N output based on rumino-hepatic circulation. However, a reduction in N intake caused massive changes in Ca and inorganic phosphate (P i ) homoeostasis in goats. Although a single dietary Ca reduction stimulated intestinal Ca absorption in a calcitriol-dependent manner, a concomitant reduction of Ca and N supply led to a decrease in calcitriol, and therefore a modulation of intestinal Ca and P i absorption. The aim of this study was to examine the potential effects of dietary N or Ca reduction separately on intestinal Ca and P i transport in young goats. Animals were allocated to a control, N-reduced, Ca-reduced or combined N-and Ca-reduced diet for about 6 − 8 weeks, whereby N content was reduced by 25 % compared with recommendations. In Ussing chamber experiments, intestinal Ca flux rates significantly decreased in goats fed a reduced N diet, whereas P i flux rates were unaffected. In contrast, a dietary Ca reduction stimulated Ca flux rates and decreased P i flux rates. The combined dietary N and Ca reduction withdrew the stimulating effect of dietary Ca reduction on Ca flux rates. The expression of Ca-transporting proteins decreased with a reduced N diet too, whereas P i -transporting proteins were unaffected. In conclusion, a dietary N reduction decreased intestinal Ca transport by diminishing Ca-transporting proteins, which became clear during simultaneous N and Ca reduction. Therefore, N supply in young ruminant nutrition is of special concern for intestinal Ca transport.Key words: Flux rates of calcium and phosphate: Goats: Na + -dependent P i transporter IIb: Transient receptor potential vanilloid channel type 6: Ussing chambersFeeding ruminants a N-reduced diet is preferable for economic and environmental reasons. Dietary crude protein (CP) concentrations of 11 − 12 % were recommended to meet the requirements of growing goats (1) . A reduced dietary N supply was associated with a significant reduction in urinary N excretion (2) due to increased expression of renal urea transporters, and thus greater renal urea re-absorption (3) in goats. In addition, the urea transporting capacity of the ruminal epithelium was increased due to dietary N reduction (4) . By possessing such efficient recycling mechanisms, ruminants such as goats are able to maintain rumen microbes' N supply, and therefore a sufficient synthesis of microbial protein as the most important source for host protein, provided that energy supply to the rumen flora is also adequate for microbial protein synthesis.As monogastric species do not have the similar potential to utilise N efficiently, a low-protein diet changes metabolic pathways seriously. A reduction of dietary protein leads to changes in Ca and inorganic phosphate (P i ) homoeostasis in monogastric animals and humans, including decrease in intestinal Ca absorption, reduced urinary Ca excretion and diminished plasma calcitriol and insulin-like growth factor 1 (IGF1) concentrations (5)(6)(7)(8) .Despite the N-rec...

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“…Calcitriol concentrations were measured by a commercial radioreceptor assay (Immundiagnostik AG, Bensheim, Germany). The calcitriol assay systems had already been used in other studies to detect caprine hormone levels [12,13]. The concentration of plasma carboxyterminal cross-linked telopeptide of type I collagen (CTX) was determined using the commercial kit Serum CrossLaps ® ELISA (Immundiagnostic Systems, Frankfurt, Germany).…”

Section: Biochemical Determinationsmentioning

confidence: 99%

Effects of a reduced nitrogen diet on calcitriol levels and calcium metabolism in growing goats

Muscher¹,

Huber²

2010

The Journal of Steroid Biochemistry and Molecular Biology

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Renal Phosphate Excretion in Goats

Cited by 14 publications

References 29 publications

Review: Regulation of gastrointestinal and renal transport of calcium and phosphorus in ruminants

Review: Regulation of gastrointestinal and renal transport of calcium and phosphorus in ruminants

Modulation of intestinal calcium and phosphate transport in young goats fed a nitrogen- and/or calcium-reduced diet

Effects of a reduced nitrogen diet on calcitriol levels and calcium metabolism in growing goats

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