Assessing the Impact of Essential Oil Blends As Antibiotic Alternatives on Nutritional and Metabolic Parameters in Non-Forage-based Diet-Fed Nellore Steers

Essential oils (EO) are antimicrobials with the potential to replace conventional ones in ruminant diets. Despite the advantage of the EO serving markets that prohibit antibiotics in animal nutrition, the results that prove their effectiveness vary with the type of EO, dose, diet, etc. This study aimed to assess the effects of a blend of essential oil, based on cinnamaldehyde and diallyl disulfide, associated or not with antibiotics on nutritional and metabolic parameters for feedlot Nellore steers fed non-forage-based diet. Five Nellore steers were distributed in a 5×5 simple Latin square design. The treatments assessed were a basal no-roughage diet with the inclusion of monensin (MON), monensin + virginiamycin (MV), monensin + blend of EO (MEO25), monensin + blend of EO (MEO35), and a blend of essential oil (EO). Feed, orts, feces, ruminal fluid, blood, and urine samples were utilized to assess the intake, digestibility, ruminal pH, ruminal NH3, nitrogen balance, microbial nitrogen synthesis, fecal cortisol metabolites, blood glucose, and D and L-lactate. No difference (P > 0.05) has been observed in additives in intake, nutrient digestibility, and ingestive behavior. There was a trend (P = 0.0553) of the effect of additives on ruminal pH, and the MV presented the highest value. No difference (P > 0.05) for the ruminal NH3, microbial N synthesis, and nitrogen balance concentration was also verified. The blood glucose and blood lactate concentration were not affected (P > 0.05) by additives. The blend of essential oils based on cinnamaldehyde and diallyl disulfide could then be indicated in replacement or association with antibiotics in a non-forage-based diet for Nellore steers.