The Effects of Phytase

Phytate phosphorus is the predominant form of phosphorus in plants and is poorly absorbed by the horse. Phytases are enzymes that break down phytate phosphorus. The use of phytase in species of livestock has shown an increase in bone strength, as well as nutritional efficiency. By potentially increasing the bone strength of young horses, fractures may become less prevalent. So UGA animal and dairy scientists conducted a project to see whether the use of phytase in young horses can increase bone mineral content, and perhaps prevent competitive horses from breaking down early. There was no change in bone composition due to the diets or phytase. However, this experiment has shown the difference between the composition of the third metacarpal and the splint bone of the horse. Phytase did increase bone calcium of the third metacarpal (cannon) bone in the horses on the adequate-P diet from 14.48 to 18.76 percent of wet weight, yet decreased bone calcium on the low-P diet from 19.17 to 16.23 percent. There was also a diet by phytase interaction within the adequate-P diet, with the addition of phytase causing P digestibility to increase from 9.48 percent to 26.04 percent. These results do not provide any support to the claim that phytase improves bone strength in horses.