本试验旨在研究饲粮中添加不同水平的低分子质量(1000 u)壳寡糖对蛋鸡生产性能、蛋品质、血清生化指标、盲肠微生物数量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58周龄海兰褐壳蛋鸡600只,随机分为4组,每组5个重复,每个重复30只.对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加300、600、900 mg/kg壳寡糖的试验饲粮.预试期为7 d,正试期为42 d.结果表明:1)添加300、600和900 mg/kg壳寡糖组的产蛋率分别比对照组提高了4.52%(P<0.05)、2.99%(P>0.05)和4.08%(P>0.05).2)试验第3、6周末,添加600和900 mg/kg壳寡糖组的鸡蛋哈夫单位分别比对照组提高了6.87%、6.69%和6.47%、6.60%(P<0.05).3)与对照组相比,饲粮添加600、900 mg/kg壳寡糖显著降低了血清葡萄糖、胆固醇含量和谷草转氨酶活性(P<0.05).4)与对照组相比,饲粮添加600、900 mg/kg壳寡糖显著提高了盲肠双歧杆菌和乳酸杆菌的数量(P<0.05),显著降低了盲肠金黄色葡萄球菌的数量(P<0.05).5)与对照组相比,饲粮添加300、600 mg/kg壳寡糖显著提高了脾脏IL?2 mRNA表达水平(P<0.05),饲粮添加600 mg/kg壳寡糖显著提高了脾脏TNF?αmRNA表达水平(P<0.05).由此可见,饲粮中添加不同水平的壳寡糖,提高了蛋鸡的产蛋率和哈夫单位,调节了肠道微生物菌群,增强了蛋鸡的免疫力,适宜壳寡糖添加水平为600 mg/kg.%This experiment was conducted to study the effects of dietary supplemented different levels low mo?lecular weight ( 1000 u) chitooligosaccharides ( COS) on performance, egg quality, serum biochemical indi?ces, cecal microbial number and gene expressions of interleukin?2 ( IL?2) and tumor necrosis factor?α ( TNF?α) in spleen of laying hens. A total of 600 Hy?line brown laying hens ( 58 weeks of age) with the similar body weight and egg production rate were randomly assigned to 4 groups with 5 replicates per group and 30 hens per replicate. Hens in the control group were fed a basal diet, and the others in the experimental groups were fed the basal diet supplemented with 300, 600 and 900 mg/kg COS, respectively. The preliminary period lasted for 7 days and the formal period lasted for 42 days. The results showed as follows:1) compared with the con?trol group, the supplementation of 300, 600 and 900 mg/kg COS group improved egg production rate by 4.52% (P<0.05), 2.99% (P>0.05) and 4.08% (P>0.05), respectively. 2) Compared with the control group, the supplementation of 600 and 900 mg/kg COS group improved Haugh units by 6.87%, 6.69% and 6.47%, 6.60% at third and sixth weeks end of the experiment (P<0.05), respectively. 3) Compared with the control group, dietary ssupplementation of 300 and 600 mg/kg COS significantly decreased the glucose, tri?glyceride contents and glutamic?oxalacetic transaminase activity in serum (P<0.05). 4) Compared with the control group, dietary supplementation of 600 and 900 mg/kg COS significantly increased the cecal Bifidobac?teria and Lactobacilli number ( P<0.05) , and significantly decreased the cecal S. aureus. number ( P<0.05) . 5) Compared with the control group, dietary supplementation of 300 and 600 mg/kg COS significantly in?creased the mRNA expression level of IL?2 in spleen (P<0.05), and dietary supplementation of 600 mg/kg COS significantly increased the mRNA expression level of TNF?α in spleen ( P<0.05) . In conclusion, dietary supplementation of different levels COS increase egg production rate and Haugh unit, modulate the cecal micro?bial community, boost the immune ability of laying hens. The recommended COS supplemental level is 600 mg/kg.
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