Evaluation of the utilisation of energy and phosphorus in field peas fed to broiler chickens.

1. The regression method was used to estimate the utilisation of energy (Experiment 1) and phosphorus (Experiments 2 and 3) in two field peas (FP) cultivars fed to broiler chickens.2. On d 17 post hatching, 240 birds were assigned to one of five experimental diets in a randomised complete block design with body weight (BW) as a blocking factor in Experiment 1. Whereas, 192 birds were allotted to one of three experimental diets on d 19 post-hatching in Experiments 2 and 3. There were eight replicate cages per diet, with six birds per cage in Experiment 1 and eight birds per cage in Experiments 2 and 3.3. Field pea cultivars Hampton (FPH) or 4010 (FP4) was incorporated at either 150 or 300 g/kg into a maize-soybean meal-based reference diet in Experiment 1. Using semi-purified diets, FPH was included at 200, 400, or 600 g/kg in Experiment 2, whereas FP4 was included at 215, 430 or 645 g/kg in Experiment 3.4. In Experiment 1 a linear decrease (P < 0.01) was observed in metabolisable energy (ME) and nitrogen-corrected ME (MEn) with inclusion of FPH in the diets, whereas both linear and quadratic effects (P < 0.05) were observed with inclusion of FP4. The regression-determined ileal digestible energy, ME and MEn were 13.70, 12.69 and 11.93 MJ/kg DM in FPH and 12.63, 13.20 and 12.52 MJ/kg DM in FP4, respectively. The ileal digestible and retainable P intakes were linearly increased (P < 0.01) with higher inclusion of FPH and FP4 in Experiments 2 and 3, respectively. The respective true ileal digestibility and true total tract utilisation of P in FPH were 74.6% and 68.3% and for FP4 were 74.3% and 61.7%, respectively. In conclusion, the estimated energy and P utilisation values could be used in diet formulations.