The Effect of Dietary Microbial Phytase on the Utilization of Lysine and Methionine in Broilers

Abstract

This experiment was conducted to evaluate the ability of supplemental microbial phytase (500 kg FTU) to improve the utilization of essential aminoacid (lysine and methionine) that could be bound to phytate. The effect of microbial phytase in performance, dressing percentage and protein efficiency ratio (PER) of the broiler were investigated through the experimental period (6 weeks). A total of 72 one-day old, unsexed commercial chicks (ROSS 308 strain) were used in this experiment. On the 7th day of age chicks were weighed and allotted randomly to 3 treatments (24 birds for each treatment, 4 replicates "6 chicks for each replicates") and experimentally fed for 7 weeks on a ground brooding rearing system. Three types of diets were used: diet (A) the positive control diet which completed in essential amino-acid according to the requirements of the broiler, diet (C) negative control based on plant protein which deficient in both lysine and methionine, diet (B) similar to diet (C) but supplemented with microbial phytase. All were formulated to be isonitorgens (23 % crud protein) and isococaloric (3100 kcal/kg). Health of the experimental stock and mortality were closely observed. Records of feed intakes weight gains and feed efficiency were taken during the feeding period. Dressing percentages were calculated after slaughtering and eviscerating. The results indicated that the microbial phytase supplementation to broiler plant based diet deficient in lysine and methionine caused a significant (p< 0.05) improvement in body weight gain and hot and cold dressing percentages with increased in feed intake. This value still significantly (p< 0.05) lower than that achieved with positive control. Also the results included that the feed efficiency value were 6 improved insignificantly (p> 0.05) by the addition of microbial phytase. But the supplementation of phytase had beneficial effect on protein efficiency ratio. The economical evaluation of addition microbial phytase to plant based diet (negative control) in this study showed an increases in net profit/kg from 1090 to 3900 sp but this values still lower than that obtained by positive control 6640 sp. 7