Effects Of Phytase Products On Performance And Nutrient Utilization Of Layer Breeders

The experiments was conducted to assess the effects of adding phytases in diet with reduced P on egg production,hatchability and nutrient utilization of breeding hens.Experiment 1: Effects of phytases on egg production and quality of breeding hens fed diet with reduced phosphorusTotal of 840 parent stock hens of Loman brown shell line at 34 wk were divided into 5 groups with 8 replications of 21 layers. After two weeks of preliminary period, the five groups of birds were offered different dietary treatments up to the end of 48wk of age respectively. The treatments includeⅠ—positive control (Ca 3.44%, nonphytate P(NNP) 0.28%),Ⅱ—negative control(36~41 wk of age--- Ca3.34%, NNP 0.15%; 42~48 wk of age--- Ca3.23%, NNP 0.13%),Ⅲ—Ⅱ+ phytase A,Ⅳ—Ⅱ+ phytase B,Ⅴ—Ⅱ+ phytase C. All phytases were supplemented at a dose rate of 300 FTU/kg. The results showed that over 35~41 wk of age, hen housed egg production(%) and feed to egg ratio were not different among all treatments (P>0.05), all indexes of egg quality were within a normal range, with fertility and hatchability being similar for all groups. Over 42~48 wk of age, the egg production was lower(P=0.083)and mortality was higher(P=0.174) for treatmentⅡthan for treatment I. Feed intake was lower (P<0.05)for treatmentⅡandⅤthan for treatmentⅠ. The egg production and mortality were improved significantly by supplementing phytases, but was not restored to the level achieved by treatmentⅠ. It seems that phytase A and B were better than phytase C although more data is required before any conclusion can be made. It can be included that adding phytases to the diets with Ca 3.34%~3.23% and NNP 0.15%~0.13% can improve the reproduction performance of breeding hens for egg line.Experiment 2: Effects of phytases on nutrient utilization of breeding hens fed diet with reduced phosphorus.A metabolism trial was conducted to assess the effect of different phytases in deit(300FTU/kg feed) on utilization of nutrients by. 5 layer hens that body weight was similar were selected from each treatment group in 49 wk, repecsively (the diet and the treatments as trial one). After 4 days preliminary period, excreta from hen was collecteh for 8 days in dry matter digestibility and phosphorus,calcium,energy and nitrogen among different phytase products(P>0.05). The phosphorus retention of treatmentⅡtended to be lower than treatmentⅠ(P=0.109). The utilization of phosphorus was higher (P=0.011) and phosphorus,calcium excretion was lower (P=0.000) for treatmentⅢthan for treatmentⅡ,Ⅳ,Ⅴ. Ash content of tibia at the end of 48 wk was lower for treatmentⅡthan for treatmentⅠ(P<0.01). The addition of phytase(Ⅲ,Ⅳ,Ⅴ) improved tibia ash content(P<0.05). The result showed: phytase in diet with reduced Ca and P can improve the nutrient utilization.