Effects of a slow-release nutritional bolus on growth performance, oxidative status, and carcass traits in fattening Holstein bulls.

This study investigated the effects of a commercial slow-release bolus supplement ("Dietevit™ Tonic") on growth performance, carcass characteristics, and oxidative stress biomarkers in fattening Holstein bulls. Twenty-four Holstein bulls (443.34 ± 25.47 kg) were randomly allocated into control and treatment groups (n = 12/group) and were fed the same basal ration under commercial farm conditions. Animals in the treatment group received a single oral bolus administration at the beginning of the trial. Body measurements, body weight, salivary oxidative stress biomarkers, and slaughter characteristics were evaluated during the 121-day trial period. On day 121, body weight, chest circumference, and chest depth were significantly higher in the bolus-treated group compared with the control group (P < 0.05). Antioxidant enzyme activities (SOD, CAT, and GPx) were significantly increased, whereas MDA and IMA concentrations were significantly decreased in the treatment group (P < 0.001). was higher in the supplemented group (61.76%) than in the control group (58.92%). The findings suggest that Dietevit™ Tonic bolus supplementation may improve growth performance, carcass characteristics, antioxidant status, and welfare-related parameters in fattening Holstein bulls under commercial production conditions.