Feed enzymes: The science, practice, and metabolic realities

The use of exogenous feed enzymes in poultry diets is becoming a norm to overcome the adverse effects of antinutritional factors and improve digestion of dietary components and bird performance. In this paper, an overview of the science behind the use of feed enzymes and the current status of enzyme technology is provided. Responses to enzyme supplementation are often variable and the reasons contributing to the observed variability are discussed. Though there are opportunities to enhance nutrient utilization with enzyme supplementation, there will be physiological limits to achievable responses. These limits are imposed by the pH and digesta retention time within the digestive tract. Nutritional strategies to, at least partly, overcome these limits need to be explored; potential approaches include feeding to restore functionality of crop and gizzard as well as the use of unconventionally high doses of enzymes. Anticipated future development of better forms of feed enzymes will also lower the physiological barriers.