Effect of phytase enzyme on layers fed plant protein diets containing low levels of available phosphorus: 1- bone characteristics, mineral retention and nutrients digestibility [electronic resouce].

Includes references.

A trial was performed to study the effect of two levels of available phosphorus (0.23 and 0.13%), and four levels of phytase enzyme (0, 100, 300 and 500 FTU/Kg) on mineral retention, nutrients digestibility and bone characteristics of 40 wks old laying hens fed diets based on corn-soybean meal compared to control diet containing 0.32% available phosphorus (AP) without phytase addition. Reducing AP without phytase addition depressed tibia breaking strength by 22.4%. Supplemental phytase by 100, 300, and 500 FTU /kg diet improved tibia breaking strength by 17.9, 6.0, and 15.8% respectively. Adding phytase improved tibial and femoral wall thickness, but still behind those of control group. Reducing AP without phytase addition showed decreases in tibial wet weight, dry weight, free fat dry weight (FFDW), and ash weight by 10.79, 10.80, 10.12 and 12.37% respectively. Adding phytase up to 500 FTU/kg diet showed insignificant improvement. Phytase addition significantly (P<0.05) increased percentage of tibial and femoral fat free DM and total ash, and insignificantly increased percentage of tibial total P and calcium by 10.79 and 10.54%, respectively. Phytase level of 100 FTU/kg diet had attained the highest values of ME, and PE. This level attained also the highest digestibility of CP, NFE. The highest value of EE digestibility was attained by phytase level of 300 FTU/kg diet (81.87%), whereas control group attained lowest value (72.15%) that was not different (P>0.05) from zero phytase group. On the other hand, phytase addition had no effect (P>0.05) on digestibilities of NFE, OM, and DM. Decreasing AP without phytase addition significantly (P<0.05) decreased ME and PE. Phytase addition increased ME and PE to the level of positive control group. Decreasing AP without phytase addition reduced phosphorus retention (P<0.05) by 30.86%. Phytase addition (300 FTU/kg diet) improved this value significantly (P<0.05) by 32.89%. Phytase addition (100 FTU/kg diet) attained highest value (65.27%) of Ca retention. Phytase addition by 500 FTU/kg diet decreased fecal phosphorus by 27.15%.

Summary in Arabic.

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