Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Joseph Moritz.


Due to depleting resources, high feed ingredient costs, and eutrophication, phosphorus nutrition in broilers has been a topic of concern for many years. The amount of damage being done to the environment by phosphorus runoff in some states has led to regulations that require broiler litter to have decreased phosphorous with the use of a phytase enzyme. There are many phytase products on the market, however, these enzymes are not all equally effective. Companies may rely only on feed manufacture retention data instead of conducting live bird performance research to test the actual efficacy of the enzyme. The first study addressed this problem by measuring in vitro retention of 9 enzymes with in vivo live bird performance variables. Results showed discrepancies between these two parameters, suggesting that enzyme efficacy should be assessed with both in vitro and in vivo studies. A second study was conducted to test the effect of poultry litter ash on feed manufacture variables as well as live bird performance variables. This study was based on the concept that poultry litter ash could replace rock phosphorus sources in the diet, therefore reducing diet cost while maintaining similar live bird performance and feed manufacture variables. Results suggested that the poultry litter ash may possess some pellet binding qualities and can increase pellet quality. Results also suggest that poultry litter ash provides utilizable phosphorus and calcium for bone mineralization, but may have some anti-nutritional factors that caused decreased live bird performance.