Magnesium in Digesta of Horses Fed Diets Containing Different Amounts of Phytate

Abstract

Approximately 70% of total plant phosphorus exists as inositol hexaphosphate (phytate). Phosphorus in phytate is generally considered to be poorly available in many mammals because 95% of phytate was recovered in the ileum of humans and dietary phytase improved phosphorus availability in pigs fed diets consisting of plant proteins rich in phytate. Phytate is also suggested to suppress magnesium absorption through making insoluble complex with magnesium because dephytinization of diets increased magnesium solubility in the small intestine and magnesium absorption (Hirabayashi, et al., 1995). On the other hand, Hintz et al. (1973) suggested that phytate phosphorus was available in equine because there was phytase activity in the lower gut. Thus, phytate may not affect magnesium absorption in horses. This experiment was conducted to study apparent magnesium movement in the gastrointestinal tract of horses fed different contents of phytate.