Effect of grain particle size on energy values and chemical components of diets for Label Rouge broilers

ABSTRACT: This study aimed to determine the apparent metabolizable energy (AME) and nitrogen-corrected AME (AMEn) values as well as the metabolizability coefficients of dry matter, protein, and ether extract of corn, pearl millet, and sorghum in different particle sizes for slow-growing broilers. Two experiments were carried out involving 280 chicks of the Label Rouge® Naked Neck broiler line, with 140 chicks allotted to each experiment in a completely randomized design. Treatments consisted of a reference diet and a test diet (60% reference diet + 40% feedstuff). The feedstuffs were tested and particle size (expressed as geometric mean diameter [GMD, μm] and geometric standard deviation [GSD], respectively) results were 816 and 1.73 for coarsely ground corn, 794 and 1.75 for finely ground corn, 1.517 and 1.92 for pearl millet grain, 760 and 1.63 for finely ground pearl millet (Experiment 1); and 1,866 and 1.86 for whole grain sorghum, 919 and 1.62 for coarsely ground sorghum, and 878 and 1.72 for finely ground sorghum (Experiment 2). A metabolism trial was conducted by using the total excreta collection method to obtain the AME and AMEn values as well as the metabolizability coefficients of dry matter, protein, and ether extract. The energy metabolization coefficient did not differ (P > 0.05) between the grains in the different tested particle sizes. However, there was an improvement in the metabolizability coefficients of dry matter, nitrogen, and ether extract as the particle size of corn was increased. In conclusion, larger grain particle sizes improve the metabolizability of nutrients and energy for slow-growing broilers. Whole-grain sorghum has limited nutritional utilization for slow-growing birds up to 21 days of age.