Performance and Phosphorus Utilization of Broiler Chickens Fed Low Phytate Barley and Pea Based Diets with Graded Levels of Inorganic Phosphorus

The effects of feeding diets based on soybean meal, low phytate hulless barley (Lphybarley) and low phytate pea (Lphypea) with inorganic phosphorus (iP) reduced by 50 or 100% to broiler chickens on performance, P digestibility and bone characteristics were investigated. Two hundred and ten day-old (Ross 308 strain) broiler chicks (5 birds per cage; 6 cages per diet) were randomly allocated to 7 dietary treatments for a 21-day study. Diets were formulated based on soybean meal-normal phytate hulless barley (SBM-normbarley) with added inorganic P (iP) to meet NRC (1994) P requirements (SBM-normbarley100) or with 50% less iP (SBM-normbarley50), soybean meal-Lphybarley-Lphypea with added iP (Lphybarley-Lphypea100) or iP reduced by 50% (Lphybarley-Lphypea50) or 100% (Lphybarley-Lphypea0), and soybean meal-normbarleynormal phytate pea (normpea) with added iP (normbarley-normpea100) or iP reduced by 50% (normbarley-normpea50). Birds fed the Lphybarley-Lphypea0 diet had the lowest (P<0.001) ADG compared with those fed the other diets. Reducing iP by 50% led to a reduction (P<0.05) in ADG for birds fed the SBM-normbarley- and normbarley-normpea-based diets but not in the Lphybarley- Lphypea-based diet. Reducing iP by 50% led to a reduction (P<0.05) in ADFI in birds fed the SBM-normbarley-based diet and normbarley-normpea-based diet compared with those fed adequate iP. Feed conversion ratio was not affected by diet throughout the experimental period (P>0.10). Reducing iP content reduced P retention in the SBM-normbarley-based diet but not in the normbarley-normpea-based diet but tibia ash and length were reduced in birds fed both diets (P<0.05). Reducing dietary iP content linearly increased (P < 0.05) P retention and linearly decreased (P<0.05) tibia ash and length in the Lphypea-Lphybarley-based diets. In conclusion, feeding a low phytate hulless barley-low phytate pea based diet with iP reduced by 50% supported similar performance as control and increased P retention, suggesting that utilizing a combination of low phytate ingredients can reduce the need for supplemental iP with significant cost and environmental implication.