Effects of phytase supplementation in mature horses fed alfalfa hay and pelleted concentrate diets.

This research investigated phosphorus (P) digestibility in mature horses using diets with and without phytase supplementation. The researchers found that the mature horses could maintain their P balance whether or not the diet was supplemented with phytase, meaning that the enzyme did not appear to improve the horses’ ability to digest and extract P from their food.

Objective and Importance of the Research

• The main objective of this study was to examine the digestibility of phosphorus (P) in mature horses, specifically regarding the potential benefits of supplementing their diets with the enzyme phytase.
• This research is particularly important because of existing environmental concerns related to phosphorus runoff. Therefore, understanding how to optimize phosphorus usage can lead to reducing waste and negative environmental impact.
• Previous research on this topic largely focused on young and growing animals, or used ponies as a model. This study filled a gap in the research by focusing on mature horses.

Methodology of the Research

• The researchers tested six diets on six mature Arabian geldings over 12 weeks. Each diet was fed to each horse for 11 days, followed by a three-day total collection of feces and urine to assess P output.
• The diets included: a control group (concentrate and hay); high P group (greater P concentrate and hay); and a forage only group. Each of these diet variations was divided into a phytase-supplemented diet and a non-phytase-supplemented diet, making a total of six diets.
• The concentrates in the diets had soybean hulls, ground corn, wheat midds, broken rice, and beet pulp, with phytase added as needed before pelleting.

Key Results and Observations

• The study revealed no significant effect of phytase supplementation on phosphorus output in urine or feces, showing no changes in P apparent digestibility between the tests with and without phytase.
• Apart from this, an analysis of the feed and feces revealed an average 93% disappearance of phytate, suggesting the high capability of horses in degrading phytate independently. This implies that phytase supplementation isn’t beneficial in mature horses.
• The research concluded that mature horses are capable of maintaining a nearly equal phosphorus balance, with an adequate amount of phosphorus provided in the diet as phytate, even without phytase supplementation.
• Another key insight gleaned from this study was that an increase in phosphorus intakes above the requirement of the horses may lead to increased detrimental outputs to the environment, thereby reemphasizing the importance of an optimized diet.

Conclusion

• Overall, this study provides critical insights into phosphorus digestibility in mature horses, finding no advantages to supplementing their diets with the enzyme phytase. Therefore, the information gleaned will be crucial for equine diet formulation and management, assisting to balance the nutritional needs of horses whilst minimizing environmental impact.