Effect of Adding Phytase to Sheep Rations on in vitro Disappearance of Dry Matter and Organic Matter and Growth Performance

2 Abstract: The current study aimed to improve the utilization of phosphorus from different feedstuffs that contain high levels of phytate phosphorus by adding different levels of phytase enzyme. Two experiments were carried out to evaluate the effects of phytase supplementation on in vitro degradation of ingredients (1 experiment), in vivo performance of growing Rahmani lambs (2 experiment). 1 experiment, dry matter and st nd st organic matter disappearance (IVDMD and IVOMD) were determined for undecorticated cottonseed meal (UCSM), wheat bran (WB), rice bran (RB) and the concentrate feed mixture (CFM) that was composed of (46.5% yellow corn, 20% undecorticated cottonseed meal, 30% wheat bran, 1% sodium chloride, 2% limestone and 0.5% vitamins and minerals mixture). These four ingredients that contained high phytate phosphorus were incubated separately with phytase enzyme (Nutrase P 500®) at 5 levels (0, 500, 1000, 1500 and 2000 IU/ Kg DM) for estimation of IVDMD and IVOMD. Adding phytase enzyme at levels of 500 and 1000 IU/ Kg DM showed the highest values of IVDMD and IVOMD for all feed types. The difference between the two levels of phytase were not significant (P>0.05). In 2 experiment, 30% Berseem hay 70% CFM basal diet with no enzyme (G ), nd 1 basal diet plus 500 IU phytase/ Kg ration (G ) and basal diet plus 1000 IU phytase/ Kg ration (G ). The results 23 showed that a significant (P<0.05) differences in final body weight gain and feed conversion were observed among the experimental groups. The highest values were recorded by lambs in G compared to other groups. 2 These results indicate that phytase supplementation to growing lamb rations improved their performance and economic efficiency.