The U.S. Poultry & Egg Assn. (USPOULTRY) and the USPOULTRY Foundation announced the completion of a funded research project at Mississippi State University in which researchers investigated the response when broilers were fed phytase enzymes.

For the project — "Response of Broilers Fed Phytase Enzymes of Different Optimal pH Ranges Alone or in Combination" — principal investigator Dr. Kelley Wamsley and colleagues at the Mississippi State University poultry science department investigated how broilers respond when fed phytase enzymes of different optimal pH ranges alone or in combination.

Phytase is an exogenous enzyme that is commonly incorporated into commercial poultry diets to increase the digestibility of phytate phosphorus. This is significant because a large majority of the ingredients used for poultry feed are plant-derived and contain phytate, according to the announcement from USPOULTRY. Phytate hinders the nutritional potential of diets and bird growth performance, leading to unreached maximal economic gain.

Phytase inclusion in broiler diets provide production advantages, such as improved growth performance and better nutrient digestibility, the news release noted. Due to the expense associated with feed, it is common for poultry nutritionists to formulate diets on a least-cost basis to maximize profit. However, lower-priced ingredients typically contain higher amounts of antinutrients, like phytate.

The objective of this research project was to determine the effects of feeding combinations of phytases with varying optimal pH ranges. The researchers theorized that if combinations of different phytases are more effective than singular use, the nutritive quality of feedstuffs would be enhanced, thereby improving broiler production, lowering feed costs and reducing the environmental excretion of phosphorus.

Two experiments were conducted.

In experiment 1, broilers were reared in raised wire cages from zero to 14 days to investigate the potential synergy of three different phytase enzymes of varying biochemical properties when fed alone or in combination with low phytase activities of either 120 or 240 phytase units (FTU) per kilogram.

Data obtained demonstrated a potential synergy with the supplementation of two phytases combined at a higher phytase activity level (240 FTU/kg), as identified from the ileal IP6 lower ester concentration, increased digestibility (calcium, phosphorus and select amino acids) and tibia ash (indicating greater phytate degradation), USPOULTRY reported.

In experiment 2, the two higher-performing phytases from experiment 1 were used to address limitations recognized in experiment 1, including: (1) utilizing a broader and more practical range of phytase activity (250 or 1,500 FTU/kg), (2) implementing three diets varying in calcium and available phosphorus and (3) employing an entire growout of broilers within the experimental floor-pen facilities.

These data demonstrated that feeding diets lowest in calcium and available phosphorus along with 1,500 FTU/kg of a single phytase resulted in improved broiler performance, tibia ash (mg/chick and concentration of select minerals) and nutrient digestibility (calcium, phosphorus and select amino acids). This strategy also demonstrated improved thigh weight at processing and indicated greater phytate degradation.

Additionally, there was some indication of synergy for the use of combined phytase at 250 FTU/kg within diets of medium calcium and available phosphorus levels (relative to reduced nutrient diets alone); however, performance was not maximized.

Overall, data do not indicate that feeding multiple phytase enzymes will contribute to significant improvements for the commercial broiler industry, according to the USPOULTRY announcement. However, these data do suggest that more attention on calcium and available phosphorus ratios can further the efficacy of phytases.

Further research on multiple enzyme use in broiler diets is warranted and could provide valuable economic and environmental insight on the strategic use of exogenous enzymes for the commercial poultry industry.

The research was made possible, in part, by an endowing foundation gift from Peco Foods and is part of the association's comprehensive research program encompassing all phases of poultry and egg production and processing. A complete report is available through www.uspoultry.org.

USPOULTRY is an all feather association progressively serving its poultry and egg members through research, education, communications and technical services. Founded in 1947, USPOULTRY is based in Tucker, Ga.