Impacts of particle size and multienzyme supplementation on growth, cost-benefit, carcass characteristics, and nutrient digestibility of broilers

Abstract

Feed intake in poultry is affected by particle sizes, with coarse particles being more favoured. However, the threshold of coarseness is yet to be established. Feeding mash diets of varying particle sizes supplemented with multienzymes to broiler chickens at both starter and finisher phases could thus help establish this threshold. The study evaluated the response of broiler chickens to diets of varying particle sizes supplemented with graded levels of multienzyme. Three sieves (3, 4, and 5 mm) were fabricated to obtain three (3) diets of different particle sizes supplemented with multienzyme at three (3) levels (0, 1, and 2 g/kg) to have nine (9) dietary treatments. A total of 450-day-old Cobb500 unsexed broiler chicks were randomly allotted to nine (9) dietary treatments with five (5) replicates of ten (10) birds each, arranged in a 3 x 3 factorial experimental layout using a Completely Randomized Design. Growth parameters, cost-benefit, nutrient digestibility, and carcass characteristics of the chickens were evaluated. Data obtained in the study were subjected to Analysis of Variance, and means were separated using Duncan Multiple Range Test. The average feed particle size ranged from 886.52 to 1329.13 mu m with a geometric standard deviation of 1.00. At the starter phase, birds fed 5 mm particles had the highest total feed intake (916.58 g/bird) and the poorest feed conversion ratio (2.65), while birds fed 3 mm particles had the lowest total feed intake (852.62 g/b) and the best feed conversion ratio (2.20). Birds fed 2 g/kg multienzyme had the highest feed costs at the starter (N 130.81) and finisher (N 331.33) phases. During the starter phase, birds offered 3 mm feed particles showed the highest (p<0.05) ether extract digestibility (0.82), while in the finisher phase, multienzyme supplementation decreased ash digestibility in birds fed diets with 3-and 4-mm feed par-ticles. The combination of multienzyme and feed particle size impacted relative breast and back weights, but not the gizzard. The study concluded that broiler chickens can be fed diets of 3 mm particle size at the starter phase and 4 mm particle size at the finisher phase, with or without multienzyme supplementation, for a better feed conversion ratio, and diets of 5 mm particles with 1 g/kg multienzyme supplementation can be fed to broiler chickens at finisher phase for improved nutrient digestibility.