本试验旨在研究饲粮中添加不同分子质量的壳寡糖对蛋鸡生产性能、蛋品质、血清生化指标、肠道微生物以及脾脏白细胞介素-2(IL-2)和肿瘤坏死因子-α(TNF-α)基因表达的影响。选取体重和产蛋率相近的70周龄海兰褐壳蛋鸡480只,随机分为4组,每组4个重复,每个重复30只鸡。对照组饲喂基础饲粮,试验组饲喂在基础饲粮中添加200 mg/kg分子质量分别为1、3和8 ku壳寡糖的试验饲粮,试验期为42 d。结果表明:1)不同分子质量的壳寡糖未显著影响蛋鸡的料蛋比、产蛋率、平均日采食量、平均蛋重(P>0.05)。2)试验第21天时,饲粮添加1、3和8 ku壳寡糖使鸡蛋的哈夫单位分别比对照组提高了3.70%(P>0.05)、5.20%(P>0.05)、12.71%(P<0.05)。3)饲粮添加3 ku壳寡糖使蛋鸡血清甘油三酯和葡萄糖含量分别比对照组降低了39.91%(P<0.05)和5.86%(P>0.05)。4)饲粮添加1 ku壳寡糖显著降低了蛋鸡肠道中的大肠杆菌和双歧杆菌数量(P<0.05)。5)饲粮添加3 ku壳寡糖显著提高了脾脏中TNF-α基因mRNA表达水平(P<0.05),添加1和3 ku壳寡糖显著提高了脾脏中IL-2基因mRNA表达水平(P<0.05)。由此可见,饲粮添加3 ku壳寡糖可以降低蛋鸡血清中甘油三酯的含量,提高脾脏IL-2、TNF-α基因mRNA的表达水平,增强蛋鸡的免疫力,所以建议添加分子质量为3 ku的壳寡糖。

This study was conducted to evaluate the effects of different molecular masses of chito-oligosaccharide (COS) on performance, egg quality, serum biochemical indices, intestinal microorganism, IL-2 and TNF-α gene expressions in spleen of laying hens. A total of 480 seventy-week-old laying hens with similar body weight and laying rate were randomly allocated to four groups with four replicate per group and 30 birds per replicate. The laying hens in control group were fed a basal diet, and those in the test groups were fed the diets with 200 mg/kg COS that molecular mass was 1, 3 and 8 ku, respectively. The experiment lasted for 42 days. The results showed as follows: 1) no significant differences were found in feed/egg ratio, laying rate, average daily feed intake (ADFI) and average egg weight (P>0.05). 2) Compared with the control group, the supplementation of 1, 3 and 8 ku COS improved Haugh unit by 3.70% (P>0.05), 5.20% (P>0.05) and 12.71% (P<0.05) at 21 days of the experiment, respectively. 3) The contents of triglyceride and glucose in serum of laying hens of 3 ku COS group were decreased by 39.91% (P<0.05) and 5.86% (P>0.05). 4) Compared with the control group, the number of intestinal E. coli and Bifidobacteria of laying hens was decreased by the supplementation of 1 ku COS (P<0.05). 5) The TNF-α gene mRNA expression level in spleen of laying hens of 3 ku COS group was significantly higher than that of the control group (P<0.05). The supplementation of 1 and 3 ku COS significantly increased IL-2 gene mRNA expression level in spleen of laying hens (P<0.05). In conclusion, the supplementation of 3 ku COS can decrease triglyceride content in serum, improve IL-2 and TNF-α gene mRNA expression levels in spleen, enhance the immune function of laying hens, and the 3 ku COS is suggested to be added.