The apparent digestibility of phytate phosphorus and the influence of supplemental phytase in horses.

The research study explores the digestibility of phytate phosphorus in horses and how it can be influenced by the addition of a dietary supplement called phytase. The experiment observed that phytase supplementation in foods may improve the digestibility of calcium in horses, particularly those consuming diets high in phytic acid.

Methodology and Experiment Setup

• The study was carried out on eight horses. They were put on four different diets according to a 4 x 4 Latin square design. These diets included one control diet and three high-P diets.
• The control diet had a low phosphorus level of 18.4g/d while the high-P diets contained phosphorus in different forms. The high-P diets included monocalcium phosphate (MCP; 43.7 g/d), myoinositol hexakisphosphate (MIHP; a compound similar to phytate present in wheat and rice bran; 41.8 g/d), and MIHP supplemented with microbial phytase (MIHPP; 42.5 g/d).
• The proportions of phytate-bound phosphorus in each diet were determined and ranged from 1% to 56%.
• The MIHPP diet was supplemented with 300 phytase units/kg to observe any influence this would have on the digestibility of phytate-bound P.
• Feces and urine were collected from the horses and analyzed for levels of phosphorus, calcium, and magnesium.

Results and Findings

• The study found that urinary phosphorus excretion was lower in horses on the control diet compared to those on the MCP diet.
• The MIHP diet had lower urinary phosphorus excretion suggesting lower phosphorus availability compared to the MCP diet. Despite this, the apparent digestibility of phosphorus did not differ significantly between these two diets.
• Apparent calcium digestibility was lower for the MIHP diet than the MCP diet, suggesting that the origin of the calcium in these diets could have influenced this result. The study found that phytase supplementation increased apparent calcium digestibility from 26.4% to 31.5%.
• The level of phytate in the diet did not influence the magnesium content.

Conclusion

• The results suggest that phytase supplementation has a more significant influence on calcium digestibility than phosphorus digestibility. This indicates that phytase supplementation could be beneficial in improving calcium digestibility for horses that are on a phytate-rich diet.