title: Absorption and secretion of calcium and phosphorus in the alimentary tract of lambs infected with daily doses of Trichostrongylus colubriformis or Ostertagia circumcincta larvae.
abstract: The flows of endogenous and exogenous calcium and phosphorus in the digesta at the abomasum, ileum and in the faeces were measured in growing lambs infected daily with 3000 T. colubriformis larvae (TC), 5000 O. circumcincta larvae or no larvae. The lambs were given 0.70 or 1.0 kg per day of a pelleted diet and the flow rates were measured by reference to soluble and particulate radioactive markers. The fraction of Ca and P in digesta of endogenous origin was measured by the method of isotope dilution involving a single intravenous dose of 45Ca or 32P. Ostertagia circumcincta infection was without effect on the absorption and secretion of Ca and P in the digestive tract, other than producing a small but significant increase in the endogenous faecal Ca excretion. There was, however, a striking increase in the flow of digesta at the abomasum, the DM and Na content of which was consistent with an increased secretion from the mucus-type cells in the abomasal mucosa. The extra digesta was absorbed in the small intestine. Trichostrongylus colubriformis infections reduced the absorption of exogenous P by about 30 per cent and increased losses of endogenous P due to the action of worms on the mucosa of the small intestine. The net effect of this was to induce a P deficiency in TC lambs, leading to a reduced flow of salivary P and a reduction in the plasma concentrations of P. The effect of TC on Ca metabolism was limited to an increase in endogenous faecal excretion.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D007408:Intestinal Absorption; D008297:Male; D010029:Ostertagiasis / Q000378:metabolism / Q000662:veterinary; D010758:Phosphorus / Q000378:metabolism*; D012756:Sheep; D012757:Sheep Diseases / Q000378:metabolism* / Q000469:parasitology; D014251:Trichostrongyloidea; D014253:Trichostrongylosis / Q000378:metabolism / Q000662:veterinary
chemical_list: D010758:Phosphorus; D002118:Calcium