Phytate and phosphorus movements in the digestive tract of horses.

The research article investigates how dietary phytate levels impact phosphorus absorption in the gut of horses. The study indicates that regardless of diet, the degradation of phytate phosphorus mainly occurs in the upper small intestine and lower large intestine, with most phosphorus absorption appearing to happen in the lower large intestine.

Methodology

• The study involved six Thoroughbred horses that were fed diets with varying levels of phytate – a low-phytate diet or a high-phytate diet – over the duration of 5 days.
• The diets provided to the horses were supplemented with Chromium Oxide (Cr2O3), which was used as an unabsorbable marker. This marker helps in tracing the movement of food in the digestive system.
• Three hours after the final feeding, the horses were euthanized and digesta collected from different segments of the intestine.

Findings

• Regardless of the diet, the daily passage of phytate phosphorus diminished in the upper small intestine and in the lower large intestine.
• The amount of phytate phosphorus passed in the lower large intestine showed no difference between horses on a low-phytate diet and those on a high-phytate diet.
• Despite these reductions, the passage of total phosphorus increased in the upper small intestine and upper large intestine for both dietary groups. However, its passage decreased in the lower large intestine.

Implications

• The reduced passage of phytate phosphorus in the upper small intestine and lower large intestine suggests that most phytate phosphorus is degraded in these areas, regardless of diet.
• Since phosphorus appears to be primarily absorbed in the lower large intestine, the results imply that phytate phosphorus is easily absorbed by horses. This hypothesis is supported by the finding that most phytate is degraded in the region of the intestine where the majority of phosphorus is absorbed.