Approaches to determine the efficiency of novel 3-phytase from Klebsiella pneumoniae and commercial phytase in broilers from 1 to 14 d of age

ABSTRACT: This study aimed to evaluate the effects of a laboratory 3-phytase (the expression of the phyK gene, Lab-Phy) and a commercial 6-phytase (Quantum Blue 40 P, Com-Phy) alone and in combination (corn-soy-based diets) in broilers. A total of 400, day-old Ross 308 male broilers were randomly assigned to 5 treatments with 10 replicate cages (8 chicks/cage) for a 14-day trial. Experimental treatments included the positive control (0.95% Ca and 0.48% nonphytate phosphorus (nPP), PC), negative control (0.90% Ca and 0.22% nPP, NC), and NC which was supplemented with Lab-Phy 250 FTU/kg and Com-Phy 250 FTU/kg alone or in combination of Lab-Phy 125 FTU/kg and Com-Phy 125 FTU/kg. The inclusion of Lab-Phy in the NC diet significantly improved the P and Ca content in the tibia compared to the NC group. Moreover, the inclusion of Com-Phy alone and in combination with Lab-Phy in the NC diet significantly increased the P and Ca content in the tibia compared to the Lab-Phy. The mRNA expression of NaPi-IIb was upregulated in the duodenum by the reduction of nPP and downregulated by the inclusion of any phytase, whereas other nutrient transporters were not influenced by the reduction of nPP or the addition of phytase in the small intestine mucosa. Broilers receiving the NC diet obtained the lowest body weight (BW) and body weight gain (BWG) at 8 to 14 and 1 to 14 d of age. The NC group showed the lowest villi height and surface area, Newcastle disease (ND) antibody titer, and digestibility of nutrients compared to the PC group at 14 d of age. Supplementing the NC diet with the Lab-Phy and Com-Phy individually, or in combination tended to improve BW, BWG, tibia characteristics, villi characteristics, ND, and retained CP and P, and apparent ileal digestibility of CP, P, methionine, and threonine. The present research indicated that the studied traits by the combination of phytases were slightly better than the average of the 2 individually, suggesting there might be some value in combining the laboratory and commercial phytases.