Effects of Corn Particle Size and Feed Form on Growth Performance and Carcass Characteristics of Broilers
Type of DegreeMaster's Thesis
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Previous research has shown that manipulation of corn particle size and feed forms have an impact on broiler growth performance. The poultry industry grinds corn to approximately 800 µm before its incorporation into broiler diets. However, coarse particles (>1,000 µm) have been reported to stimulate gizzard development in broilers and reduce electrical energy consumption during grinding. Three trials were conducted to determine the effects of feeding broilers with different corn particle size during the starter (1 to 14 d), grower (14 to 28 d), and finisher (28 to 42 d) periods in order to determine the optimum corn particle size in each phase. Each trial evaluated the effects of 4 corn particle sizes. In trial 1 corn was ground to 674, 741, 805, and 912 µm, in trial 2 corn was ground to 629, 763, 814, and 1,779 µm and in trial 3 corn was ground to 615, 863, 1,644, and 2,613 µm. In trials 1 and 2, the particle size of corn did not influence body weight (BW), feed intake (FI) and feed conversion ratio (FCR). In trial 3, the particle size of corn particle did not influence BW and feed intake of broilers. However, FCR improved on birds fed diets with corn particles ground to 863 µm at 42 d of age compared with those fed diets with corn particles of 1,644 µm and 2,613 µm. These data indicated that coarser particles can be fed during the production periods of broilers without a negative effect on growth parameters although particles >1,600 µm may compromise FCR at 42 d. Currently, the majority of broiler producers are feeding crumbles during the starter period (1 to 14 d) and 4.4 mm pellets in subsequent phases. However, one processing alternative to improve broiler productive parameters could be feeding 3.3 mm micro pellets during the starter period. Two trials were conducted to evaluate the effects of feeding 3.3 mm micro pellets on broiler performance and carcass characteristics. In the first trial 5 treatments were evaluated during the starter period and consisted of a combination of 3 dietary feed forms: 1) mash from 1 to 14 d, 2) crumbles from 1 to 14 d, 3) 3.3 mm micro pellets 1 to 4 d and then crumbles to 14 d, 4) 3.3 mm micro pellets 1 to 7 d and then crumbles to 14 d, and 5) 3.3 mm micro pellets from 1 to 14 d. Common grower and finisher diets were offered in a 4.4 mm pelleted form from 15 to 35 d of age. The second trial consisted of a 3 x 2 factorial arrangement with 3 feed forms (mash, crumbles + 4.4 mm pellets, and 3.3 mm micro pellets) and 2 amino acid (AA) densities (88 and 96% AA of Aviagen Recommendations). In trial 1, birds fed mash diets during the starter period (1 to 14 d) had the lowest BW and feed intake at 35 d compared to birds fed either crumbles or 3.3 mm micro pellets. However, no differences in FCR were observed at 35 d. The usage of 3.3 mm micro pellets during the starter improved breast meat weight at 35 d of age. In trial 2, birds fed 4.4 mm pellet and 3.3 mm micro pellets had higher BW, FI, carcass and breast meat weight and better FCR than birds fed mash diets at 42 d of age. In addition, birds fed diets with 96% of dietary AA had higher BW, carcass yield, carcass weight, and breast meat weight and better FCR than birds fed diets with 88% of dietary AA. These data demonstrated that broilers can be fed 3.3 mm micro pellets during the starter period and/or during a 6 wk production period of broilers.