Effects of supplementation of manganese with or without phytase on growth performance, carcass traits, muscle and tibia composition, and immunity in broiler chickens

An experiment was conducted to study the effect of Mn and phytase supplementation on performance, carcass traits, and immunity in broiler chickens. A total of 350 one-day-old unsexed broiler chickens were randomly allotted to 7 dietary treatments (5 replicate pens of 10 chicks per pen) in a 1+3×2 factorial arrangement with 3 concentrations of supplemental Mn and with or without phytase addition. The control diet represented a basal diet with no supplemental Mn and phytase. The basal diet was supplemented with Mn at 50, 75, and 100 mg/kg diet and microbial phytase was added at a dose of 500 FTU/kg. Average daily gain, feed intake, and feed conversion ratio were similar among the treatments. During the starter, grower, and finisher periods, 5, 7.5, and 17.5% of the broiler chickens, respectively, developed leg abnormalities in the control diet, which were not observed in the treatment groups. The serum concentrations of glucose, total cholesterol, Ca, and P were not affected by supplemental Mn and phytase or their interaction. Antibody titer against Newcastle virus disease vaccine on 16 d and 32 d of the feeding trial (10 d after vaccination) were increased (P<0.05) by Mn or phytase supplementation, but the antibody titer was not affected by the Mn and phytase interaction. Carcass traits such as hot carcass weight, eviscerated carcass weight, dressing percentage, breast, leg, frame, and giblet were not altered by Mn or phytase or both supplementation. Abdominal fat content was decreased (P<0.05) by high concentrations of Mn supplementation (75 and 100 mg/kg), but not by phytase addition. Chemical composition (moisture, protein, ash, and fat) in thigh and breast muscle, and total ash, Ca, and P concentrations in tibia at 42 d were similar among the dietary treatments. Thus, supplementation of Mn at 75-100 mg/kg to a basal corn-soybean diet could be beneficial for improving immunity and decreasing fat deposition, and phytase supplementation could also improve immunity measures in broiler chickens.