Enzyme complex and Saccharomyces cerevisiae in diets for broilers in the initial phase

SUMMARY This study aimed at evaluating the use of exogenous enzymes in diets with Saccharomyces cerevisiae and their impact on zootechnical performance, carcass yield, intestinal histomorphometry and of broiler diets in the initial phase. A completely randomized design was used in a 2×3 + 1 factorial arrangement, with two levels of enzyme complex (EC), (0 and 200g / ton), three yeast levels (0, 6 and 12%) and a control diet, making up seven treatments, with five replicates of 20 broilers per experimental unit. We evaluated the performance (feed intake, weight gain and feed conversion ratio), carcass yield and cuts, histomorphometry of the small intestine (height, circumference and width of villi, height and width of the crypt, thickness of the intestinal muscle wall and villi/crypt relationship). From 1 to 7 and 1 to 21 days, the inclusion of yeast led to reduced broiler performance. At 21 days, the addition of EC resulted in an increase of (p <0.05) in the thickness of the muscular wall of the duodenum and decreased the width of the crypt in the ileum. The 12% level of yeast without the EC provided a thicker jejunum intestinal muscle wall when compared to the positive control. There was no significant effect on carcass yield and cuts between treatments. In conclusion, the inclusion of yeast reduces performance from 1-21 days. The enzyme complex and yeast does not change the performance or carcass yield, however, it does bring benefits to the intestinal mucosa.

摘要 本研究旨在评估日粮中外源酶（exogenous enzymes）与酿酒酵母（Saccharomyces cerevisiae）的联用效果，及其对育雏期（initial phase）肉鸡（broiler）日粮的动物生产性能（zootechnical performance）、屠宰性能（carcass yield）、肠道组织形态学（intestinal histomorphometry）的影响。试验采用完全随机设计（completely randomized design），设置2×3+1因子排列（factorial arrangement）：2个酶复合物（enzyme complex, EC）添加水平（0与200g/吨）、3个酵母添加水平（0、6%与12%），另设1个基础对照日粮，共7个处理组，每个试验单元（experimental unit）设置5个重复，每重复包含20羽肉鸡。本研究测定的指标包括：生产性能指标（采食量（feed intake）、体增重（weight gain）与饲料转化率（feed conversion ratio））、屠宰性能及屠体分割性状（carcass cuts）、小肠（small intestine）组织形态学指标（绒毛（villi）高度、周长与宽度、隐窝（crypt）高度与宽度、肠道肌层厚度及绒毛隐窝比值）。在1~7日龄与1~21日龄育雏阶段，日粮中添加酵母会降低肉鸡的生产性能。至21日龄时，添加酶复合物可使十二指肠（duodenum）肌层厚度显著提升（p<0.05），同时降低回肠（ileum）隐窝宽度。相较于阳性对照组（positive control），未添加酶复合物的12%酵母添加组的空肠（jejunum）肌层厚度更厚。各处理组间的屠宰性能及屠体分割性状均无显著差异。综上，日粮中添加酵母会降低肉鸡1~21日龄阶段的生产性能。酶复合物与酵母联用并不会改变肉鸡的生产性能或屠宰性能，但可对肠道黏膜产生有益影响。