PURPOSE: This study aimed to assess the anticoccidial effects of betaine and a vaccine compared to monensin sodium in experimentally induced coccidiosis in broiler chickens. METHODS: 600 day-old broiler chickens (Ross 308) were randomly assigned to five groups, each with four replicates of 30 birds. While the control group received a basal diet, two experimental groups received basal diet supplemented with either 100 mg/kg monensin sodium or 2.0 g/kg betaine. The remaining experimental groups received a commercial coccidiosis vaccine alone or in combination with betaine. All chickens were challenged with sporulated field-mixed Eimeria species at 20 days of age. RESULTS: Throughout the study, vaccinated birds showed superior performance in terms of body weight gain (BWG) and feed conversion ratio (FCR) compared to other anticoccidial treatments (P <
0.05), followed by betaine, vaccine + betaine, and monensin treatments in descending order. While all anticoccidial regimens significantly reduced fecal oocyst output only at the beginning of the observation period, this effect diminished thereafter (P <
0.05). Supplementation with monensin and vaccination against coccidiosis significantly decreased small intestine weight compared to untreated controls (P <
0.01), with a numerical decrease observed in chicks fed betaine-supplemented diets and treated with the combination of betaine and vaccine. CONCLUSION: Notably, there has been no prior study comparing betaine with monensin sodium and a coccidiosis vaccine. These findings suggest that dietary betaine supplementation and a commercial coccidiosis vaccine containing mixed Eimeria spp. may offer benefits in controlling coccidiosis, presenting viable, cost-effective, sustainable, and safe alternatives to conventional ionophore anticoccidials, with added benefits of no residue and reduced resistance hazards for both animal and human consumption.