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Summary: This study assesses the efficacy of 2 different potentiated ionophores (monensin and narasin) and a chemical (nicarbazin, a shuttle) in program with narasin to control coccidiosis in challenged male broilers through the evaluation of performance and macroscopic lesions of internal organs. A total of 4,400 broiler chicks were housed in 44 floor pens of 100 birds each; birds of the first group were fed a narasin/nicarbazin (NN)–containing diet from 0 to 27 D of age followed by narasin diet until market age, and those of group 2 were fed a monensin/nicarbazin diet followed by narasin ration for the same trial periods. The coccidia challenge was performed at day 1 by the inclusion of a proven Eimeria-infected litter in the bedding of all floor pens followed by an oral challenge using a commercial cocci vaccine at 7 D of age with a concentration of 11 times the vaccine dose. Although results showed that NN and monensin/nicarbazin treatments both demonstrated efficacy at reducing coccidian lesions, NN significantly increased BW and reduced feed conversion ratio (P < 0.05) at 27 (1,405 vs. 1284 g and 1.458 vs. 1.566, respectively) and at 33 D of age (2,178 vs. 2,026 g and 1.549 vs. 1.642, respectively). Weight and weight percentages of the ready-to-cook carcass and carcass cutup parts were significantly improved by NN. Narasin/nicarbazin inclusion in diet for 0 to 27 D followed by narasin until market weight was a successful strategy because, in addition to preventing and controlling coccidiosis, it improved performance of broiler chickens.

Summary: 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.