Productive and physiological performance of two local strains of chickens at early period of laying as affected by enzyme supplementation under summer conditions of Egypt

A total of 360 pullets at 22 weeks of age, from two local strains (Mandarah and Dokki-4) 180 birds each, were used to study the effect of dietary phytase supplementation on productive and physiological performance of two local strains of chickens during early period of laying under summer conditions. The experiment continued for 12 weeks from 22 up to 34 weeks of age. The birds were randomly distributed into six treatments, each of two replicates (fifteen of each strain).The experimental treatments were two levels of nonphytate phosphorus (NPP) 0.45% (control) and low-NPP (0.25°h), and three levels of microbial phytase (0 ,500 and 1000 u/kg of diet). The experimental treatments were as follows: 0.45% NPP- control diet. low NPP- diet (0.25%). 0.45% NPP- control diet supplemented with microbial phytase at a level of 500/kg. -low NPP-diet (0.25%) supplemented with microbial phytase at a level of 500 U/kg. - 0.45% NPP- control diet supplemented with microbial phytase at a level of 1000 U/kg. - low NPP- diet (0.25%) supplemented with microbial phytase at a level of 1000 U/kg. Studied criteria were: performance of egg production, egg quality, plasma Ca, P, cholesterol , total protein, albumin and globulin, and liver parameters (LDL, HDL and total lipids). The obtained results showed that: Hens fed 0.45%-NPP-diets supplemented with phytase (500 or 1000 u/kg of diet) gave higher final body weight , body weight gain and significantly improved feed conversion as compared with the hens fed 0.45% or 0.25%-NPP-diets without phytase supplementation. Hens fed 0.45%-NPP-diets supplemented with phytase (500 or 1000 u/kg of diet), showed an increase in egg number and egg weight and improvement in some egg quality parameters in Mandarah strain compared to Dokki-4 strain. However, hens fed 0.45%-NPP-diets performed better than those fed 0.25%-NPPdiets for egg production and feed conversion..