The role of phosphate on the rates of mineral absorption from the forestomach of sheep.

Phosphorus plays an important role in calcium and magnesium homeostasis in ruminants. In five trained sheep, each with a large rumen cannula, the isolated rumen wash technique was used to measure the magnesium and calcium absorption rates from the rumen. After one control period of measurement, the intra-ruminal phosphate concentration was increased from 2 to 10 mmol/L, and there was a significant increase in the calcium and magnesium absorption rates. The same technique was also used to demonstrate the effect of hyperphosphatemia on the absorption rates of magnesium and calcium from the forestomach. Although the absorption rates of magnesium and calcium tended to increase, the changes were not statistically significant. It is concluded that intra-ruminal phosphate concentration plays a role in the absorption of magnesium and calcium ions from the forestomach of sheep.