This experiment was conducted to assess a protocol combining 20% excess dietary methionine above the modern breeder pullet's requirement and AviPro MGF vaccine in controlling Mycoplasma gallispeticum (MG) infection. In a complete randomized design, a total of 276 6-wk-old breeder pullets, of the Ross 308 strain were allocated into 4 treatments, each with 3 floor pen replicates of 23 birds/pen: 1) nonvaccinated with adequate methionine (NVAM), 2) nonvaccinated with 20% excess methionine (NVEM), 3) Vaccinated with adequate methionine (VAM), 4) Vaccinated with 20% excess methionine (VEM). Vaccination with AviPro MGF at 6 wk of age was performed via drinking water. Results indicated that the rate of depictable growth and tracheal colonization of MGF vaccine strain is 6 wk postvaccination. Sera Elisa titers showed that an 8-wk-postvaccination period was required for the vaccine to stimulate the humoral immunity response against MG. The 20% excess methionine numerically increased the IgG titer against MG in comparison to other groups, yet this increase was not enough to generate protective titer count. Furthermore, the addition of 20% excess methionine above the recommended levels hindered the tracheal colonization rate and log10 values of AviPro MGF vaccine colony forming units from 5.9/mL of tracheal swab suspension in VAM group to 0.82/mL of tracheal swab suspension in VEM group (P ˂ 0.05). In conclusion, the 20% excess methionine above the modern requirements reduced the tracheal colonization of F-strain MG. Further research is needed to confirm the ability of excess dietary methionine to enhance the adaptive and acquired immunity of broiler breeder pullets.

进行该实验是为了评估将超过现代种鸡需要量的 20% 过量日粮蛋氨酸和 AviPro MGF 疫苗结合起来控制鸡支原体( MG ) 感染的方案。在一个完整的随机设计中，总共 276 只 6 周龄的罗斯 308 品系种鸡被分配到 4 个处理中，每个处理 3 个地板栏重复，每栏23 只鸡：1) 未接种足量蛋氨酸 ( NVAM ) , 2) 未接种 20% 过量蛋氨酸 ( NVEM )，3) 接种足量蛋氨酸 ( VAM)), 4) 接种了 20% 过量的甲硫氨酸 (VEM)。在 6 周龄时通过饮水接种 AviPro MGF。结果表明，MGF 疫苗株的可描述生长和气管定植率为接种后 6 周。Sera Elisa 滴度表明，疫苗需要 8 周的接种后期才能刺激针对 MG 的体液免疫反应。与其他组相比，20% 过量的甲硫氨酸在数值上增加了针对 MG 的 IgG 滴度，但这种增加还不足以产生保护性滴度计数。此外，添加超过推荐水平 20% 的过量蛋氨酸阻碍了 AviPro MGF 疫苗菌落形成单位的气管定植率和 log10 值，从 VAM 组的 5.9/mL 气管拭子悬液到 VEM 组的 0.82/mL 气管拭子悬液(P ˂ 0.05)。总之，超过现代要求的 20% 过量甲硫氨酸减少了 F 菌株 MG 的气管定植。需要进一步的研究来确认日粮中过量的蛋氨酸能够增强肉种鸡小母鸡的适应性和获得性免疫力。