Site of Phosphorus Absorption in the Sheep

Wright, Evan

doi:10.1038/176351a0

Cited by 19 publications

(8 citation statements)

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“…Absorption of phosphorus from the rumen has been discussed [15], and does not appear to be negligible [16][17][18] even though quantitative data are rare [19]. The abomasum does not absorb phosphorus [9] and the post-rumen absorption sites are distributed in the gut.…”

Section: The Mechanisms and Sites Of Phosphorus Absorptionmentioning

confidence: 99%

II. Quantitative aspects of phosphorus absorptionin ruminants

Bravo

Sauvant

Bogaert³

et al. 2003

Reprod. Nutr. Dev.

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-Phosphorus absorption in ruminants was analysed from a database described in a previous article. For common values of ingested phosphorus (2.5-5.0 g·kg -1 of DM), 0.73 of dietary phosphorus is absorbed. The remaining variability is probably due to phosphorus quality. Phosphorus absorbed from silage, cereal, cereal by-products and hay differs greatly. The current true absorption coefficient used to calculate daily phosphorus supply is a constant value in the current systems and often it underestimates the true absorption resulting in an excess of phosphorus being supplied in the diets. Adjusting the true absorption coefficient values requires better characterisation of the phosphorus supplied by each feedstuff. Dietary influences (phytate phosphorus, crude fibre, etc.) were investigated but trials assessing the ration effect on phosphorus absorption are lacking. Since rumen microbes have specific phosphorus requirements, particularly for cell-wall degradation, the feedstuff phosphorus availability for the rumen ecosystem is discussed.absorption / availability / phosphorus / quantitative aspect

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Section: The Mechanisms and Sites Of Phosphorus Absorptionmentioning

confidence: 99%

II. Quantitative aspects of phosphorus absorptionin ruminants

Bravo

Sauvant

Bogaert³

et al. 2003

Reprod. Nutr. Dev.

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“…For some time phosphorus balance was thought to be largely regulated by intestinal absorption (Wright, 1955;Hill, 1962). However, some recent studies have led to the suggestion that the salivary glands may represent the major site of control (Tomas, 1974a,b;Tomas & Somers, 1974) and a model has been proposed to explain how variation in faecal phosphorus excretion is achieved.…”

Section: Discussionmentioning

confidence: 99%

“…Until recently control of absorption was generally held to be the major regulator (Wright, 1955;Hill, 1962). Against this, however, some workers have suggested that the salivary glands by controlling phosphorus secretion into the gut may be more important (Tomas, 1974a, b).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Variation in Phosphorus Intake on Net Intestinal Phosphorus Absorption, Salivary Phosphorus Secretion and Pathway of Excretion in Sheep Fed Roughage Diets

Scott¹,

McLean

Buchan³

1984

Exp Physiol

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SUMMARYMature sheep fitted with rumen and duodenal cannulae and fed either pelleted hay or grass diets were given supplements of Na2HPO4 by continuous infusion into the rumen and the effects on salivary phosphorus secretion, intestinal phosphorus absorption and pathway of excretion were studied. Little phosphorus was excreted in the urine in control periods and little increase was seen in response to phosphorus supplementation, most of the extra phosphorus given being recovered in the faeces. Infusion of phosphorus into the rumen led to an increase in the flow of phosphorus to the intestine, an increase in absorption, a rise in plasma phosphate level and an increase in salivary phosphorus secretion while withdrawal of supplementary phosphorus was seen to have the opposite effects. In separate studies short sections of the upper small intestine temporarily isolated from the normal flow of digesta were perfused with solutions containing NaH2PO4 (5-50 mmol.1-1). Phosphorus absorption increased with increasing concentration though the relationship was curvilinear such that absorptive efficiency fell from around 0-7 at 5 mmol . 1-1 to around 0-35 at a concentration of 50 mmol. 1-1. The significance of these results in relation to the control of phosphorus balance in ruminants is discussed.

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“…Comparisons of P concentrations in rumen fluid and venous blood (Parthasarathy, 1952;Parthasarathy, Garton & Phillipson, 1952) and between arterial and venous blood draining the reticulo-rumen (Yano, Sekiya, Kawashima & Kumada, 1978) did not indicate any significant phosphate passage. Injection of the tracer 32P either into the rumen (Scarisbrick & Ewer, 1951;Parthasarathy et al 1952;Wright, 1955;Pfeffer, 1968) or intravenously Smith, Kleiber, Black & Baxter, 1955) showed that the rumen epithelium was permeable to phosphate in both directions though all authors agree that only insignificant amounts of phosphate appear to move across the wall.…”

Section: Introductionmentioning

confidence: 99%

FLUX OF INORGANIC PHOSPHATE ACROSS THE SHEEP RUMEN WALL IN VIVO AND IN VITRO

Breves¹,

Höller²,

Packheiser³

et al. 1988

Exp Physiol

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SUMMARYExperiments were done in vivo and in vitro to study the flux of inorganic phosphate (Pi) across the rumen wall in sheep. The technique of the temporarily isolated and washed reticulo-rumen was applied to measure Pi net flux at nine different Pi concentrations in the buffer solutions introduced into the reticulo-rumen for 1 h. Six sheep were either P replete (4-25 g P d-l) or in a P-depleted state (1-05 g P d-1). Under both dietary treatments Pi net secretion into the reticulorumen was found at Pi concentrations between 0 1 and 2-2 mmol 1-1 whereas Pi net absorption was observed at P, concentrations between 4-1 and 15 8 mmol 1-1. There

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Site of Phosphorus Absorption in the Sheep

Cited by 19 publications

References 2 publications

II. Quantitative aspects of phosphorus absorptionin ruminants

II. Quantitative aspects of phosphorus absorptionin ruminants

The Effect of Variation in Phosphorus Intake on Net Intestinal Phosphorus Absorption, Salivary Phosphorus Secretion and Pathway of Excretion in Sheep Fed Roughage Diets

FLUX OF INORGANIC PHOSPHATE ACROSS THE SHEEP RUMEN WALL IN VIVO AND IN VITRO

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