II. Quantitative aspects of phosphorus absorptionin ruminants

Bravo, David; Sauvant, Daniel; Bogaert, Catherine; Meschy, François

doi:10.1051/rnd:2003020

Cited by 28 publications

(41 citation statements)

References 58 publications

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“…The difference between intake and excretion of calcium was 12.20, 61.65, 74.22 and 64.10% for the doses 0.0, 0.8, 1.6 and 2.4%, respectively, whereas for the phosphorus levels, the excretion was greater than the intake, possibly because there was some imbalance between the minerals and also because of the greater amounts of endogenous phosphorus losses. Louvandini & Vitti (2007), Bravo et al (2003a) and Dias et al (2007) commented that the increase in the phosphorus content in the sheep diet increases its absorption and excretion through the feces, which is the preferential pathway for elimination. Louvandini & Vitti (2007) claimed that the phosphorus consumed and that present in the urine are associated with the stabilization of the endogenous fecal loss, associated with the excess material ingested and the type of feed ingested, since the greater the effective fiber content ingested, the more salivation and excretion of phosphorus through the feces (Bravo et al, 2003b).…”

Section: Resultsmentioning

confidence: 99%

Intake, performance and nutrient digestibility of sheep fed sugarcane treated and ensiled with calcium oxide or urea

et al. 2013

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-The objective of this study was to evaluate intake, performance and nutrient digestibility of sheep supplemented with sugarcane ensiled with four levels of calcium oxide (0.0, 0.8, 1.6 and 2.4%) and urea (1.5%), on a natural matter basis. Twenty castrated Santa Ines lambs with 24.09 kg average weight were housed in individual 1.5 m 2 pens, distributed in a completely randomized design. The diet supplied had a roughage:concentrate ratio of 70:30 and the experimental period lasted 77 days, of which 14 days were used for adaptation to the diet and three 21-day periods for data collection. No differences were observed for the average daily intake of dry matter, ether extract, neutral detergent fiber, neutral detergent fiber corrected for ash and protein, total carbohydrates, hemicellulose and total digestible nutrients. The treatment with urea showed differences for the intake (kg/day) of crude protein, acid detergent fiber and non-fibrous carbohydrates. There was no effect of diets on the digestibility of dry matter, ether extract, neutral detergent fiber, acid detergent fiber or total digestible nutrients, but there was a quadratic effect for total carbohydrates and increasing linear effect for non-fibrous carbohydrates. The calcium intake increased as the levels of calcium oxide in the sugarcane were elevated. The calcium:phosphorus ratio in the silage of calcium oxide was different from the silage with urea and control. No effect was observed for the performance characteristics of sheep. Sugarcane silages with calcium oxide levels of up to 2.4% or with urea do not improve the intake or weight gain of sheep.

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Section: Resultsmentioning

confidence: 99%

Intake, performance and nutrient digestibility of sheep fed sugarcane treated and ensiled with calcium oxide or urea

et al. 2013

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“…for examples). Because most of this higher fluid throughput stems from saliva inflow into the digestive tract, this system has an increased potential to provide gastrointestinal microbes with additional nutrients, such as recycled nitrogen or phosphorus (Lapierre and Lobley, ; Bravo et al., ), possibly making ruminants somewhat less dependent on the nutrient influx via food intake.…”

Section: Discussionmentioning

confidence: 99%

The effect of very low food intake on digestive physiology and forage digestibility in horses

Clauss

Schiele

Ortmann

et al. 2013

Animal Physiology Nutrition

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Equid digestion is often conceptualized as a high-throughput/low-efficiency system, in particular compared with ruminants. It is commonly assumed that ruminants have an advantage when resources are limited; the effect of low food intake on digestive physiology of horses has, however, not been explored to our knowledge. We used four adult ponies [initial body mass (BM) 288 ± 65 kg] in two subsequent trials with grass hay-only diets [in dry matter (DM): hay1, mid-early cut, crude protein (CP) 10.5%, neutral detergent fibre (NDF) 67.6%; hay2, late cut, CP 5.8%, NDF 69.5%], each fed subsequently at four different dry matter intake (DMI) levels: ad libitum and at 75, 55 and 30 g/kg(0.75) /day. We particularly expected digesta mean retention times (MRT) to increase, and hence fibre digestibility to increase, with decreasing DMI. Ponies maintained BM on the first, but lost BM and body condition on DMI55 and DMI30. MRTs were negatively correlated to DMI and ranged (for particles <2 mm) from 23/31 h (hay1/2) on the ad libitum to 38/48 h on DMI30. Digestibilities of DM, nutrients and fibre components decreased from DMI75 to DMI30; apparent digestibilities of organic matter and NDF (hay1/2) dropped from 47/43% and 42/37%, respectively, on the ad libitum DMI to 35/35% and 30/28% on DMI30. Additional differences evident between the two hays included a higher estimated 'true' protein digestibility for hay1 and finer faecal particles on hay2; there were no differences in faecal particle size between intake levels. The results suggest that below a certain food intake threshold, the major digestive constraint is not fermentation time but nutrient supply to gut bacteria. The threshold for such an effect probably varies between feeds and might differ between ruminants and equids.

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“…According to Kebreab and Vitti (2005), 45% of the total rumen P is recycled in saliva and many studies have shown that salivary P is in the inorganic form (Tomas, 1973;Scott and Buchan, 1987;Bravo et al, 2003). Although salivary secretion rate is affected by diet, concentration of Pi in saliva appears to remain constant (Tomas, 1973).…”

Section: The Rumenmentioning

confidence: 99%

“…Several models have been created to examine changes in P metabolism with dietary changes (Vitti et al, 2000;Bravo et al, 2003;Dias et al, 2006). However, these models have been created to interpret in vivo tracer kinetic data from small ruminants.…”

Section: Introductionmentioning

confidence: 99%

A Model of Phosphorus Digestion and Metabolism in the Lactating Dairy Cow

Hill

Knowlton

Kebreab

et al. 2008

Journal of Dairy Science

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A dynamic, mechanistic, compartmental model of phosphorus (P) digestion and metabolism was constructed in the Advanced Continuous Simulation Language using conservation of mass principles and mass action kinetics. Phosphorus was assumed to exist in 3 forms: inorganic (Pi), phytic acid (Pp), and organic (excluding phytic acid; Po). All 3 forms were assumed to be present in the digestive tract with absorption of Pi into blood. Inputs to the model were total P intake; Pp, Po, and Pi as proportions of total P; milk yield; rate of salivation (fixed at 239 L/d); and rate of liquid passage from the rumen (fixed at 198 L/d). The model was fitted to 2 experiments from the literature. Derived parameters were well defined by the data. With a mean observed P intake of 75 g/d, total tract P digestibility was 38%. Phytic acid P digestibility in the rumen was 74%, with no additional Pp digestion in the lower tract. Inorganic P and Po digestibility in the lower tract were 48 and 89%, respectively. Flows of Po and Pi from the rumen were 2.4 and 3.0 times greater than intake, respectively. The increase in Po was apparently due to microbial growth. The increase in Pi arose primarily from secretion of Pi into the rumen via salivation where 65% of absorbed P was recycled to the rumen. Milk synthesis used 30% of absorbed Pi, and 1% was excreted in urine. This research suggested that the primary regulation points for maintaining blood P were bone deposition and resorption and absorption from the intestine. However, because bone P balance was related to both dietary P intake and ruminal phytase activity, it is critical to achieve a better understanding of phytate digestibility across several feeds if dietary P is to be reduced below current requirements.

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II. Quantitative aspects of phosphorus absorptionin ruminants

Cited by 28 publications

References 58 publications

Intake, performance and nutrient digestibility of sheep fed sugarcane treated and ensiled with calcium oxide or urea

Intake, performance and nutrient digestibility of sheep fed sugarcane treated and ensiled with calcium oxide or urea

The effect of very low food intake on digestive physiology and forage digestibility in horses

A Model of Phosphorus Digestion and Metabolism in the Lactating Dairy Cow

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