Phytate-bound phosphorus in horse nutrition: Digestive utilization, phytase supplementation, and environmental implications

Abstract

In equine nutrition, phosphorus (P) is a critical nutrient essential for bone development, energy metabolism, and various physiological functions. However, the bioavailability of phosphorus in common feedstuffs, particularly in the phytate form found in cereals, poses a challenge for efficient nutrient utilization by horses. This review delves into the distinctive digestive physiology of horses as monogastric herbivores, focusing on the utilization and digestibility of dietary phosphorus. It explores the mechanisms of phosphorus absorption in horses, the role of microbial phytase in the hindgut, and the influence of various factors, including feed composition, processing methods, and calcium-to-phosphorus ratios on phosphorus digestibility. Additionally, the review addresses the environmental implications of phosphorus excretion, particularly its potential to contribute to eutrophication and water contamination if not properly managed. This article also discusses strategies to enhance phosphorus utilization in horses, including the use of low phytic acid crops, precise ration formulation, and supplementation with exogenous phytase. These strategies have the potential to improve nutrient efficacy and reduce phosphorus excretion despite the limited research on phytate metabolism in mature horses. The review underscores the need for further research on phosphorus requirements across different life stages of horses and the implication of sustainable measures to regulate phosphorus emissions from equine farms. In conclusion, optimizing phosphorus utilization will not only enhance equine health and performance but also contribute to environmental sustainability by mitigating the ecological impact and pollution associated with phosphorus use.