Effects of Adding Different Levels of Phytase to Diet Containing Low Phosphorus on Performance, Shell Quality and Bone Parameters in Laying Japanese Quail

This experiment was carried out to determine the effect of addition of different levels of phytase containing low phosphorus diets on performance, eggshell quality and bone characteristics in laying Japanese quail (Coturnix japonica). In the experiment, a total of 162 7-week-oldlaying Japanese quail were fed two different diets containing 0.33 % available phosphorus (AP, control) and 0.15 % AP supplemented with phytase 0, 500, 1000, 1500, 2000 phytase unites/g feed. Each diet was feed to groups having three replicates, each cages nine quail, in completely randomized design. Feed and water supplied for ad-libitum. Light was provided 17 hours daily. Egg production, egg mass, average daily feed consumption, viability, fat-free dried tibia weight were improved, as phytase level increased in the diet. However, final live weight, carcass weight, body weight gain, feed efficiency, tibia ash (%) and deformed egg ratio (%), some eggshell quality parameters measured in eggs collected at the end of the first period, were not affected by treatments. With regard to measured parameters, the responses of laying quail, to the increasing phytase levels, were not linear. The performance and bone parameters of the group fed with 1500 units were very close to that of the control group, even higher than the control group in some traits. Decreasing in shell weight of eggs collected at last three days of the experiment were not prevented any of the phytase levels. At the same period, shell thickness and breaking strength of the eggs of groups fed with 1500 and 2000 units phytase, were significantly lower than that of the control group. Manure ash percentage of phytase added groups were significantly lower than the control group