Effects of Phytase Supplementation of Low Protein Diets on Performance, Egg Quality Traits and Blood Biochemical Parameters of Laying Hens

Effects of phytase supplementation of low protein diets on performance, egg quality traits and blood biochemical parameters of laying hens were evaluated by using 216 Lohmann LSL-Lite hens. Birds were randomly divided in 36 cages (n=6). Based on a 3×2 factorial arrangement of treatments, 6 iso-caloric experimental diets consisting three levels of crude protein (CP, 150, 138, and 126 g/kg) and phytase (0 and 300 FTU/kg) were formulated and fed to hens with 6 replicates per diet. Collected data of feed intake (FI), egg production (EP), egg mass (EM) and calculated feed conversion ratio (FCR), egg quality traits and blood parameters during 7-wk trial period were analyzed based on completely randomized design. Decreasing dietary crude protein significantly decreased EP, EM and FI and increased FCR (P < .05). In the first egg sampling (wk 3) egg index, yolk index, yolk color, egg gravity, shell weight and shell thickness were not significantly affected by dietary treatment (P > .05). Decreasing dietary CP significantly increased Haugh unit compared to the control group. In the second egg sampling period (wk 7), Haugh unit significantly decreased in the hens fed low protein diets compared to the control group (P < .05). Phytase supplementation did not have any beneficial effect on productive performance of laying hens and egg quality traits (P > .05). There was no interaction between protein level and phytase on egg traits except for egg index (P < .05). There was no interaction between CP levels and phytase on blood parameters except for Heterophil count (P < .01). Interaction between protein levels and phytase on lymphocyte as well as heterophil to lymphocyte (H/L) ratio was significant (P < .05). In conclusion, feeding low CP diets significantly decreased blood levels of cholesterol, triglycerides and LDL in compared to the control group (P < .05).