Effect Of Available Phosphorus Levels And Crude Phytase On Performance, Nutrient Retention, Tibia Quality And Blood Criteria By Laying Hens

A study was conducted to determine the effects of available phosphorus levels and crude phytase on layer.Used 70 weeks old New Loman Laying Hens,study included feeding and metabolism experiments. Criteria used were performance, nutrient retention, tibia quality and blood criteria. The treatment diets were fed in a factorial arrangement of two levels of crude phytase(0,0.5%) and three levels available P(0.1%,0.2%,0.4%).the results are as follows: PerformanceResults of 6 weeks feeding experiment are as follows: 0.1% Ap diet with 0.5% crude phytase, resulted in increased egg production by 8.61 percentage points, increased feed consumption by 2g/2wk, improved average egg yield by 6.51g/(d · bird), descended feed egg ratio by 11.65%, reduced percentage of defective eggs by 1.22 percentage points, improved eggshell thickness by 1.62× 10-1mm 2.45× 10-1mm, 3.35× 10-1 mm and strength by 1.04 kg/cm2, 1.30 kg/cm , 1.63 kg/cm during 2,4,6 weeks of feeding experiment. Performance of hens fed 0.1 %Ap diet with 0.5% crude phytase attained or exceeded that of hens fed 0.4% AP diet without crude phytase. Nutrients RetentionResults of 1 week metabolism experiment are as follows: 0.1% Ap diet with 0.5% crude phytase made apparent retention of GE, CP, Gly, Ca, P, Fe, Mn, Zn significantly(P<0.05) improved by 3.55%, 5.21%, 1.72%, 60.02%, 329.88%, 11.49%, 15.72%, 40.51 percentage points respectively.0.2% Ap diet with 0.5% made these criteria improved by smaller range. When AP level depressed, crude phytase made apparent retention of Cu reduced significantly. 0.4% Ap diet with 0.5% crude phytase had a trend.to descend the apparent retention of Ca,Fe,Mn. There was no significant effects of AP and crude phytase in apparent retention of DM and all AA except for Gly (P>0.05.) . Tibia Quality and Blood CriteriaAP and crude phytase had no significant influence on tibia ash, ash percentage, Ca content of tibia ash, plasma Ca and P, AKP activity. 0.1% Ap diet with 0.5% crude phytase creased P content of tibia ash significantly(P<0.05). P content of tibia ash of Hens fed the 0.1 %Ap diet without 0.5% crude phytase was 10.97%,significant lower than that of hens fed 0.2%,0.4% AP diet with or without crude phytase. When 0.1 %Ap diet supplemented with 0.5% crude phytase, P content of tibia ash was 17.99%,have no difference with that of diet with 0.2%,0.4% AP diet with or without crude phytase (P>0.05 ) .