A novel consensus bacterial 6-phytase variant completely replaced inorganic phosphate in broiler diets, maintaining growth performance and bone quality: data from two independent trials.
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Total replacement of dietary inorganic phosphate (Pi) by a novel consensus bacterial 6-phytase variant (PhyG) in phytate-rich diets (>0.3% phytate-P) was investigated in 2 trials using growth performance and bone quality as outcome measures. Both trials utilized a completely randomized design with 5 dietary treatments across 4 phases: starter (0-10d), grower (10-21d), finisher 1 (21-35d), and finisher 2 (35-42 d). Treatments comprised a nutritionally adequate positive control (PC) diet containing monocalcium phosphate and 4 experimental diets (IPF1, IPF2, IPF3, and IPF4), all containing no added Pi and reduced in Ca by 0.2 to 0.3% units vs. PC. IPF1contained PhyG at 1,000 FTU/kg (all phases); IPF2 contained PhyG at 1,000 FTU/kg (all phases) and was additionally reduced in digestible AA, ME, and sodium (-0.2 to -0.4% points, -74kcal/kg, -0.04% points, respectively, vs. PC); IPF3 contained PhyG at 3,000 FTU/kg in starter, 2,000 FTU/kg in grower, and 1,000 FTU/kg in finisher phases; and IPF4 contained xylanase (2,000 U/kg) and PhyG (2,000 FTU/kg in starter, 1,500 FTU/kg in grower, and 1,000 FTU/kg in finisher phases) and was additionally reduced in ME (-71kcal/kg vs. PC). Ross 308 broilers were used (trial 1: n=1,200 mixed sex; 24 birds per pen 10 replicates; trial 2: n=1,300 males; 26 birds 10 replicates). During all phases in both trials, all IPF treatments maintained or improved BW, ADG, ADFI, FCR and BW-corrected FCRc and bone quality parameters vs. PC. vs. PC, treatment IPF3 increased ADG during starter phase (+10.8%) and reduced overall FCRc (-12 points, P<0.05) in Trial 1, and increased overall ADG (+4.4%), day 35 and day 42 BW (+3.5%, +4.9%), and reduced overall FCRc (-11 points) in Trial 2 (P<0.05). IPF4 produced equivalent performance to IPF3 (both trials). These are the first data to demonstrate total replacement of Pi by microbial phytase during an entire growth cycle in broiler diets.
author list (cited authors)
Marchal, L., Bello, A., Sobotik, E. B., Archer, G., & Dersjant-Li, Y.
complete list of authors
Marchal, L||Bello, A||Sobotik, EB||Archer, G||Dersjant-Li, Y