Performance and carcass characteristics of broilers fed whole corn germ

ABSTRACT The objective of this study was to evaluate the effect of including whole corn germ (WCG) on the performance; diet metabolizability; yields of carcass, cuts, and offal; and quality of meat of broilers. A total of 648 chicks were assigned to six treatments in a completely randomized design with six replicates, with 18 birds in each. Treatments consisted of a corn- and soybean meal-based control diet (0 g kg−1 WCG) and five test diets including WCG at the levels of 40, 80, 120, 160, and 200 g kg−1. Birds and diets were weighed at each seven days to determine feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR). The partial collection methodology was employed to determine the apparent metabolizable energy (AME), nitrogen-corrected AME (AMEn), and the apparent metabolizability coefficients of gross energy (AMCGE), dry matter (AMCDM), crude protein (AMCCP), and ether extract (AMCEE) of the diets. In the evaluation of meat quality, we analyzed the pH, cooking losses, shear force, water-holding capacity, color, and peroxide index of the meat. There was a difference for BWG and FCR in the total rearing period (1 to 42 days), for which optimum BWG was estimated as 2921 g/bird, with 118 g kg−1 inclusion of WCG. There was no difference for the AME, AMEn, and AMCCP of the diets, although AMCGE, AMCDM, and AMCEE declined as WCG was included. The increasing levels of WCG did not influence the yields of carcass and cuts or the meat quality. There was an increase in the yield of gizzard and proventriculus. Whole corn germ can be used at low levels in the diet of broilers without compromising their productive rates.摘要 本试验旨在探究添加全玉米胚芽（whole corn germ, WCG）对肉鸡生产性能、日粮代谢率、胴体及分割肉与内脏副产品产率，以及肉品品质的影响。本试验共选用648羽肉鸡雏鸡，采用完全随机设计分为6个处理组，每组设置6个重复，每个重复18羽肉鸡。处理组包含1组玉米豆粕型基础日粮（WCG添加量为0 g·kg⁻¹），以及5组试验日粮，其WCG添加水平分别为40、80、120、160和200 g·kg⁻¹。每7天对肉鸡和日粮进行称重，以计算采食量（feed intake, FI）、体增重（body weight gain, BWG）及饲料转化率（feed conversion ratio, FCR）。采用分步收粪法测定日粮的表观代谢能（apparent metabolizable energy, AME）、氮校正表观代谢能（nitrogen-corrected AME, AMEn），以及总能（gross energy, AMCGE）、干物质（dry matter, AMCDM）、粗蛋白（crude protein, AMCCP）和粗脂肪（ether extract, AMCEE）的表观代谢系数。在肉品品质评定环节，本试验测定了肉样的pH值、蒸煮损失、剪切力（shear force）、持水力（water-holding capacity）、色泽及过氧化值（peroxide index）。全饲养周期（1~42日龄）内，肉鸡的体增重（BWG）与饲料转化率（FCR）存在显著差异，经估算，当WCG添加量为118 g·kg⁻¹时，肉鸡体增重可达最优值2921 g/羽。日粮的表观代谢能（AME）、氮校正表观代谢能（AMEn）及粗蛋白表观代谢系数（AMCCP）未受WCG添加的显著影响，但随着WCG添加水平提升，总能表观代谢系数（AMCGE）、干物质表观代谢系数（AMCDM）与粗脂肪表观代谢系数（AMCEE）均呈下降趋势。WCG添加水平的提升对肉鸡胴体、分割肉产率及肉品品质均无显著影响。肉鸡肌胃（gizzard）与腺胃（proventriculus）的产率随WCG添加水平提升显著升高。全玉米胚芽可在肉鸡日粮中以低水平添加，且不会对其生产性能造成不利影响。