本试验通过在饲粮中添加不同菌种、不同水平的同源乳酸菌制剂,研究其对肉仔鸡生长性能、免疫机能和肠道形态结构的影响,比较2种乳酸菌的应用效果,进而确定饲粮中适宜的乳酸菌添加水平。选用1日龄健康爱拔益加肉公雏288只,随机分成6组,每组4个重复,每个重复12只鸡,Ⅰ组为对照组,饲喂基础饲粮;Ⅱ组为抗生素组,饲喂基础饲粮＋0.01%黄霉素;其余4组为乳酸菌制剂组,乳酸菌制剂活菌数量为5×10⁸~6×10⁸ CFU/g(Ⅲ组:基础饲粮+0.2%草乳杆菌制剂;Ⅳ组:基础饲粮+1.0%草乳杆菌制剂;Ⅴ组:基础饲粮+0.2%格氏乳杆菌制剂;Ⅵ组:基础饲粮+1.0%格氏乳杆菌制剂),0.2%、1.0%添加水平在全价料中的有效乳酸菌数量分别为1×10⁶、5×10⁶ CFU/g,试验期28 d。结果表明:1)饲粮中添加乳酸菌制剂可不同程度地改善肉仔鸡生长性能,0.2%、1.0%水平乳酸菌均可显著提高1~28 d肉仔鸡平均日增重、降低料重比(P<0.05),同一菌种的1.0%添加组显著高于0.2%添加组(P<0.05),但不同菌种的同一添加水平间差异不显著(P>0.05)。2)在饲粮中添加乳酸菌能不同程度提高肉仔鸡血清中免疫球蛋白G(IgG)和免疫球蛋白A(IgA)的含量,除第4周时IgA含量外,第2周和第4周时1.0%添加组均显著高于对照组(P<0.05),但0.2%添加组与对照组均差异不显著(P>0.05),不同菌种的同一添加水平间也差异不显著(P>0.05)。3)第2周和第4周时,1.0%添加组肉仔鸡外周血T淋巴细胞增殖反应均显著高于对照组(P<0.05);除对照组外,其余各组间均无显著差异(P>0.05)。4)在绒毛高度,第2周时仅1.0%草乳杆菌组显著高于对照组(P<0.05),第4周时0.2%、1.0%草乳杆菌组和1.0%格氏乳杆菌组均显著高于对照组(P<0.05);在隐窝深度,第2周时1.0%添加组显著低于对照组(P<0.05),第4周时0.2%、1.0%草乳杆菌组显著低于0.2%格氏乳杆菌组(P<0.05)。由此可知,饲粮添加同源乳酸菌均可不同程度改善肉仔鸡生长性能、免疫机能及肠道形态结构,且同一菌种添加1.0%的作用效果优于0.2%,同一添加水平草乳杆菌的作用效果优于格氏乳杆菌。

The experiment was conducted to study the effects of homology Lactobacillus preparation with different strains and supplemental levels in diets on growth performance, immune function and intestinal structure of broilers. The objective of this study was to compare the application effects of different strains and to find the suitable supplemental level in diets of broilers. A total of 288 one-day-old healthy AA broilers were randomly assigned to 6 groups with 4 replicates per group and 12 broilers per replicate. The number of live lactic acid bacteria in Lactobacillus preparation was between 5×10⁸ CFU/g and 6×10⁸ CFU/g. The experimental treatments were divided as follows: group Ⅰ, the control, basal diet; group Ⅱ, the antibiotic, basal diet+0.01% flavomycin; group Ⅲ, basal diet+0.2% L. graminis preparation; group Ⅳ, basal diet+1.0% L. graminis preparation; group Ⅴ, basal diet+0.2% L. gasseri preparation; group Ⅵ, basal diet+1.0% L. gasseri preparation. The number of live lactic acid bacteria in Lactobacillus preparation was equivalent between group Ⅲ and group Ⅴ, and between group Ⅳ and group Ⅵ, and they were 1×10⁶ and 5×10⁶ CFU/g, respectively. The experiment lasted for 28 days. The results showed as follows: 1) the supplementation of Lactobacillus in the diet could improve growth performance of broilers to some degree. Supplementation of 0.2% and 1.0% Lactobacillus in the diet could both increase the average daily gain and decrease feed/gain of broilers aged from 1 to 28 days (P<0.05). There was no significant difference between different strains at the same supplemental level (P>0.05), but the effects of 1.0% groups were better than those of 0.2% groups in the same strain (P<0.05). 2) The contents of IgG and IgA in serum of broilers in Lactobacillus groups were improved to some degree, except for IgA content in 1.0% groups at week 4, they were higher than those in the control group at week 2 and 4 (P<0.05), but there were no significant differences among 0.2% groups and the control group, and between different strains at the same supplemental level (P>0.05). 3) At week 2 and 4, T lymphocytes proliferative response in peripheral blood of broilers in 1.0% groups was significantly higher than that in the control group (P<0.05), except for the control group, there were no significant differences among the other groups (P>0.05). 4) About the height of small intestinal villi of broilers fed with Lactobacillus, only 1.0% L. graminis preparation group at week 2, 0.2% and 1.0% L. graminis preparation groups and 1.0% L.gasseri preparation group at week 4 were significantly higher than the control group (P<0.05); about crypt depth, 1.0% groups were significantly lower than the control group at week 2 (P<0.05), and 0.2% and 1.0% L. graminis preparation groups were significantly lower than 0.2% L. gasseri preparation group at week 4 (P<0.05). In conclusion, homology Lactobacillus can effectively improve growth performance, immune function and intestinal structure of broilers. For the same strain, the effects of 1.0% supplementation are better than those of 0.2% supplementation, and the effects of L. graminis supplementation are better than those of L. gasseri supplementation.