title: Phosphorus net absorption in dairy cows subjected to abomasal infusion of inorganic phosphorus--a pilot study.
abstract: In this pilot study, the effects of phosphorus (P) supply on inorganic phosphorus (Pi ) net absorption in dairy cows were investigated. Three non-lactating, non-pregnant, rumen-fistulated Swedish Red breed dairy cows were studied in a 3 × 3 Latin square design. Monosodium dihydrogen orthophosphate dihydrate (NaH2 PO4 *2H2 O) was continuously infused into the abomasum for 4 days. The solutions provided 0, 14.4 or 28.8 g Pi /day. Rumen fluid volume and outflow rate were estimated at day four of each experimental period using cobalt-lithium EDTA as an external marker. Acid insoluble ash in feeds and faecal samples was used to quantify P faecal excretion. Concentrations of Pi in collected samples of rumen fluid, blood, faeces and urine were determined. Pi flow into the small intestine increased (p < 0.05) with Pi infusion. Pi net absorption tended to increase (p = 0.08) but proportion of absorbed Pi tended to decrease (p = 0.08). Urinary Pi excretion was negligible and did not affect P homoeostasis (p = 0.50). There was no change in plasma Pi concentration (p = 0.45) in response to Pi infusion. The increase in total faecal P excretion (p < 0.05) with increasing level of infused Pi was solely because of increased soluble faecal Pi (p < 0.05). It is suggested that at P overfeeding, intestinal Pi net absorption is saturable in dairy cows.
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Kungsängen Research Centre, Uppsala, Sweden. kamyar.mogodiniyai.kasmaei@slu.se
authors.forename: K
authors.initials: K
authors.lastname: Mogodiniyai Kasmaei
authors.forename: K
authors.initials: K
authors.lastname: Holtenius
mesh_terms: D000018:Abomasum / Q000502:physiology*; D000818:Animals; D001826:Body Fluids; D002417:Cattle / Q000097:blood / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005260:Female; D010758:Phosphorus / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D010865:Pilot Projects; D012417:Rumen / Q000737:chemistry
chemical_list: D010758:Phosphorus