| dc.description.abstract | The use of phytase in broiler production has increased since its adoption as a feed additive. Published information supports the use of phytase to improve the digestibility of Ca and P; however, sources are conflicted about the effectiveness of phytase to improve amino acid and energy digestibility. Therefore, the objective of this research program was to explore the opportunity for use of high levels of phytase to improve poultry production parameters through increased nutrient utilization. It was hypothesized that through dietary manipulation of Ca and P levels, phytase would have a positive impact on growth performance and egg production. In an experiment, broilers were fed diets with reduced digestible amino acid density and increasing levels of phytase. It was observed that as amino acid density was reduced, growth parameters suffered. However, increasing inclusion of phytase improved growth parameters and was able to recover growth performance lost with the reduction of amino acid density. The results of the experiment provide implications for industry nutritionists where elevating phytase inclusion can lead to improved breast yield and increased profits. Additionally, broiler production performance losses resulting from reducing feed costs through reduced amino acid density can be offset with a high level of phytase. In a series of 2 trials, broilers were fed diets with reduced nutrient density (amino acid density and metabolizable energy), Ca, P and 2 levels of phytase. It was observed that increasing the inclusion of phytase led to improved growth, while reducing amino acid density had a negative impact. Results identified the influence of Ca and P levels on the impact of phytase. In reduced nutrient diets, reducing Ca and P had a positive influence on broiler growth and allowed a high level of phytase to recover lost growth performance associated with reduced nutrient density. The implications of this data are that utilizing reduced nutrient densities to lower dietary cost, phytase can be positively influenced with a reduction of Ca and P through increased nutrient digestibility. The effect of a high level of phytase on egg production of laying hens was evaluated. Laying hens were fed an industry-type positive control, a negative control with reductions in Ca, P and Na, while a high level of phytase was supplemented in the negative control. It was observed that the reduction of minerals had a negative impact on egg production and size; however, phytase was able to improve egg production and egg size. Additionally, the inclusion of phytase was able to recover apparent metabolizable energy (AME) that was lost with the reduction of minerals in the negative control. These data imply that a high inclusion of phytase fed to laying hens can improve nutrient digestibility of AME, Ca, P and Na leading to improved production of laying hens. In conclusion, the use of high levels of phytase can improve poultry growth performance and production characteristics through improved nutrient digestibility. In broilers this is accomplished through increased breast yield, while in layers it is through increased egg production and size. This research program identifies the importance of adequate understanding of mineral and nutrient levels in poultry formulation with high levels of phytase. | en |
