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

Scott, D.; McLean, A. F.; Buchan, W.

doi:10.1113/expphysiol.1985.sp002888

Cited by 14 publications

(23 citation statements)

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“…Furthermore, P concentration in plasma was related to endogenous P excreted in feces (F"2e. "a; r = 0.71, P < 0.01), indicating greater P in plasma might have induced a greater secretion of endogenous P (Mañas-Almendros et al, 1982;Scott et al, 1984) and, consequently, a greater excretion in feces. In agreement with Preston and Pfander (1964) and Vitti et al (2005), endogenous (also called metabolic) fecal P increased with increasing dietary P. Endogenous fecal P can be derived either from inevitable fecal losses or from fecal excretion of surphis P (Pfeffer et al, 2005).…”

Section: P Intake Excretion and Secretionmentioning

confidence: 90%

“…Although it is considered negligible, P excretion in urine of ruminants contributes to P homeostasis. According to various studies (Field et al, 1983;Scott et al, 1984;Scott and Buchan, 1985), when plasma P increases above a concentration threshold (about 2 mmol/L), the reabsorptive capacity of kidney tubules is exceeded and extra P is excreted in urine. In this sttidy, plasma P concentrations were above this concentration (2.15, 2.55, 2.83, and 2.81 mmol/L for LP, MP, HP, and SP, respectively).…”

Section: P Intake Excretion and Secretionmentioning

confidence: 97%

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An extended model of phosphorus metabolism in growing ruminants1

Dias

López

Patino

et al. 2011

Journal of Animal Science

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A major objective of this study was to extend the Vitti-Dias model used to describe P metabolism in ruminants, by adding 2 new pools to the original model to represent the rumen and saliva. An experiment was carried out using 24 male sheep, initial BW of 34.5 kg, aged 8 mo, fed a basal diet supplied with increasing amounts of dicalcium phosphate to provide 0.14, 0.32, 0.49, and 0.65% P in the diet. Sheep were individually housed indoors in metabolic cages and injected with a single dose of 7.4 MBq of (32)P into a jugular vein. Feed intake and total fecal and urinary outputs were recorded and sampled daily for 1 wk, and blood samples were obtained at 5 min, and 1, 2, 4, 6, 24, 48, 72, 96, 120, 144, and 168 h after (32)P injection. Saliva and rumen fluid samples were taken on d 6, 7, and 8. Then, animals were slaughtered and samples from liver, kidney, testicle, muscle, and heart (soft tissue) and bone were collected. Specific radioactivity and inorganic P were then determined in bone, soft tissue, plasma, rumen, saliva, and feces, and used to calculate flows between pools. Increased P intake positively affected total P (r = 0.97, P < 0.01) and endogenous P excretion in feces (r = 0.85, P < 0.01), P flow from plasma to saliva (r = 0.73, P < 0.01), from saliva to rumen (r = 0.73, P < 0.01), and from lower gastrointestinal tract to plasma (r = 0.72, P < 0.01). Urinary P excretion was similar for all treatments (P = 0.35). It was, however, related to plasma P (r = 0.63, P < 0.01) and to net P flow to bone (accretion - resorption; r = -0.64, P < 0.01). Phosphorus intake affected net P flow to soft tissue (P = 0.04) but not net P flow to bone (P = 0.46). Phosphorus mobilized from bone was directed toward soft tissue, as suggested by the correlations between P flow from bone to plasma and net P flow to soft tissue (r = 0.89, P < 0.01), and P flow from plasma to soft tissue and net P flow to bone (r = -0.76, P < 0.01). The lack of effect of dietary P on net P accretion in bone suggests that P demand for bone formation was low and surplus P was partially used by soft tissue. In conclusion, the model resulted in appropriate biological description of P metabolism in sheep and added knowledge of the effects of surplus dietary P on P metabolism. Additionally, the model can be used as a tool to assess feeding strategies aiming to mitigate P excretion into the environment.

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Section: P Intake Excretion and Secretionmentioning

confidence: 90%

Section: P Intake Excretion and Secretionmentioning

confidence: 97%

An extended model of phosphorus metabolism in growing ruminants1

Dias

López

Patino

et al. 2011

Journal of Animal Science

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“…In sheep, the upper small intestine is the major absorptive site with both active transport and passive diffusion mechanisms (Care, 1994). With perfusion of the temporarily isolated upper small intestine with NaH 2 PO 4 (5 to 50 mmol/L), Scott et al (1984) reported a curvilinear relationship between P absorption and P concentration; absorption efficiency fell from 0.74 at 5 mmol/L to 0.35 at 50 mmol/L. It was also reported that in sheep, as dietary P increased from 2.5 to 5.0 g/kg of DM, total P absorbed increased but efficiency of absorption was constant (Bravo et al, 2003a,b).…”

Section: Digestion and Absorption Of P In The Digestive Tractmentioning

confidence: 99%

“…Salivary P was estimated as the difference between duodenal P flow and P intake (Scott et al, 1984(Scott et al, , 1985Scott and Buchan, 1987). In monogastrics, the kidneys are most important in removing excess P from the blood, whereas, in ruminants, the salivary glands play this role (Care, 1994).…”

Section: Salivary P Secretionmentioning

confidence: 99%

“…Whether similar processes are dominant in ruminants is unclear. The general form of the relationship between supply and absorption of P is that increasing P flow decreases absorption efficiency, suggesting that a carrier-mediated system might be involved, at least in sheep (Scott et al, 1984). Care et al (1980) indicated active transport was involved in P absorption in sheep based on the evidence that total P absorbed reached plateau when the P content of a perfusate was increased to 15 mmol/L.…”

Section: Introductionmentioning

confidence: 98%

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Effect of dietary phosphorus on intestinal phosphorus absorption in growing Holstein steers

Feng

Ronk

Hanigan

et al. 2015

Journal of Dairy Science

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The effect of dietary P intake on intestinal P absorption was evaluated in growing Holstein steers. Diets varying in P content (0.15, 0.27, 0.36, and 0.45%, DM basis) were fed to 8 steers (174±10kg of BW) fitted with permanent duodenal and ileal cannulas in a replicated 4×4 Latin square with 14-d periods. Ytterbium-labeled corn silage and cobalt-EDTA were used as particulate and liquid phase markers, respectively, to measure digesta flow. Duodenal and ileal samples and spot urine samples were collected every 9 h from d 11 to 14. Total fecal collection was conducted on d 11 to 14 with fecal bags. Blood samples were collected from the coccygeal vessel on d 14. Feed, digesta, and fecal samples were analyzed for total P and inorganic P. Data were analyzed using PROC GLIMMIX in SAS with a model including treatment, square, period, and interaction of treatment and square. Preplanned contrasts were used to evaluate linear and quadratic treatment effects. Results were reported as least squares means. Dry matter intake (mean=4.90kg/d, 2.8% of BW) and apparent DM digestibility (mean=78.1%) were unaffected by treatment. Duodenal and ileal flow of total P increased linearly with increasing P intake (13.4, 18.5, 23.0, and 27.4g/d; 6.80, 7.87, 8.42, and 10.4g/d). Increasing P intake increased the quantity of P absorbed from the small intestine linearly (6.96, 11.1, 14.6, and 17.2g/d), but absorption efficiency was unchanged (mean=59.6%). Phosphorus was absorbed on a net basis from the large intestine, but this was not affected by treatment and was a small proportion of total P absorption. Blood inorganic P increased linearly with increased dietary P (4.36, 6.31, 7.68, and 8.5mg/dL) and salivary P secretion was unchanged (mean=5.79g/d), suggesting that rumen function was prioritized during short-term P deficiency. These data showing an absence of change in absorption efficiency and salivary P secretion in the face of short-term P deficiency may be used to improve published models of P digestion, absorption, and metabolism.

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The effect of dietary intake of calcium and dry matter on the absorption and excretion of calcium and phosphorus by growing lambs

Field

Woolliams²,

Dingwall

1985

J. Agric. Sci.

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The isotope dilution technique was used to measure endogenous faecal excretion and absorption of dietary Ca and P by growing lambs. Groups of four lambs were given 0-8 or 1-2 kg/day of a pelleted barley and soya-bean diet containing 4-2 g P/kg D.M. and supplemented to contain 1-79, 3-52 or 4-67 g Ca/kg D.M.At the lowest dietary concentration of Ca, absorption of Ca was insufficient to meet the Ca required for deposition in the newly formed bone matrix of the skeleton; retention was 0-39, 1-16 and 1-12 g/day with increasing dietary Ca concentration. The proportion of dietary Ca absorbed decreased (P < 0-001) with increasing Ca intake, ranging from 0-85 to 0-44. Endogenous faecal excretion of Ca was independent of the absorption of dietary Ca, but increased (P < 0-05) from 17-2 at the lower to 21-1 mg/kg live weight/day at the higher D.M. intake. Plasma concentration of Ca was higher for the female (2-51) than the male (2-33 mmol/1) lambs and increased linearly (P < 0-001) with dietary concentration of Ca from 2-31 to 2-52 mmol/1.The retention of P increased with Ca and D.M. intake. On the other hand, the proportion of dietary P absorbed (0-85) was independent of Ca intake and hence of P retention. Increases in P retention were reflected by decreases in urinary P, but not in endogenous faecal excretion. Endogenous faecal excretion of P increased with D.M. or P intake from 17-9 at the lower to 33-5 mg/kg live weight/day at the higher intake.The results are discussed in relation to dietary allowances of Ca and the mechanism of P homoeostasis. TNTROTYTTPTTONmaintenance requirements consist predominantly of unabsorbed secretions of minerals into the digestive Two major difficulties exist in the factorial tract, any factor which alters the rate of secretion approach to the prediction of the dietary require-or the absorbability of the minerals in the secretions ments of ruminants for Ca and P . These are the will alter requirements. Many factors, including the choice of value for the coefficient of absorption of physical nature and quantity of feed (Bailey & dietary Ca and the maintenance requirements of Balch, 1961) are known to increase the volume of P. The difficulty with Ca is that ruminants absorb secretions and Braithwaite (1982,1983) has recently Ca according to needs (Agricultural Research shown experimentally that faecal excretion of endo-Council, 1980). Thus the wide divergence in the genous Ca varies directly with feed intake. Of published values for the proportion of dietary Ca greater concern is whether salivary P, the main absorbed (see Agricultural Research Council, 1980) source of secretion of P, is determined by the can be attributed to the fact that in many of these quantity of P absorbed surplus to requirements or studies Ca intake was rarely limiting and, for a by the actual quantity of P absorbed. The latter given net requirement, the proportion will vary would imply that maintenance requirements are inversely with Ca intake.not constant but vary with the requirements for In the factorial approach t...

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

Cited by 14 publications

References 0 publications

An extended model of phosphorus metabolism in growing ruminants1

An extended model of phosphorus metabolism in growing ruminants1

Effect of dietary phosphorus on intestinal phosphorus absorption in growing Holstein steers

The effect of dietary intake of calcium and dry matter on the absorption and excretion of calcium and phosphorus by growing lambs

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