Evaluating the efficacy of maternal bovine appeasing substance in reducing stress and enhancing growth performance in dairy calves after disbudding.

The objective of this study was to investigate the effects of a maternal bovine appeasing substance (MBAS) and analgesia and anesthetics (A/A) on stress (measured via hair and serum cortisol) and performance (ADG and number of disease treatments) following caustic paste disbudding. Calves from 3 dairy farms in Texas were transported to a commercial heifer rearing ranch (d -1), weighed, and randomly assigned to 1 of 4 treatment groups (n = 30/treatment) before hutch placement: (1) receiving caustic paste only (negative control, CON); (2) receiving 5 mL of MBAS above the muzzle and 5 mL behind the poll (100 mg/mL; MBAS), (3) receiving an analgesic (transdermal flunixin meglumine, 3.3 mg/kg BW) and anesthetic (2% lidocaine, 2 mL/horn bud; A/A-CON); or (4) receiving both MBAS and A/A (A/A-MBAS). The MBAS was applied upon arrival (d -1), followed by the administration of A/A 24 h later (d 0) and the application of caustic paste within 10 min. Blood was collected via jugular vein within 1 h before disbudding (0hSERUM), 4 h after disbudding (4hSERUM), and 7 d later (d7SERUM). Tail hair samples were collected on arrival (d1HAIR) and 14 d later (d14HAIR), and BW was measured on d -1, 14, 28, and 65 and at weaning to calculate ADG. Numbers of treatments for pneumonia, bloat, fever, diarrhea, navel infection, and total treatments until weaning were recorded. Calf was considered the experimental unit for all analyses. Differences in initial BW, ADG, and cortisol concentrations (hair and serum) were analyzed for the fixed effects of MBAS, A/A, and their interactions, with random variables for calf within MBAS × A/A × farm and farm itself using the MIXED model procedure in SAS. Cortisol concentrations included covariates of 0hSERUM for 4hSERUM and d7SERUM, and d1HAIR for d14HAIR. Significance was declared at P ≤ 0.05 and tendencies at P ≤ 0.1. Cortisol concentrations increased from d1HAIR to 14dHAIR and for all calves and tended to be higher in calves not treated with A/A. Interestingly, calves that received MBAS or A/A had a numerical decrease in serum cortisol before and after disbudding, whereas calves that did not receive A/A or MBAS had an increase. For MBAS-treated calves, 4hSERUM tended to be lower than non-MBAS-treated calves. Calves treated with MBAS had a higher ADG until d 14 and tended to be greater until d 28. The only effects on the number of treatments observed were that MBAS calves tended to receive more treatments for fevers compared with non-MBAS-treated calves. These results show that administering MBAS before caustic paste disbudding positively influences ADG and may help suppress the initial cortisol rise after disbudding, thereby enhancing early calf performance.