The aim of this study was to investigate the effect of kefir as a probiotic on the performance and health status of calves. Thirty Holstein female calves with 3-day-old were randomly allocated to three treatment groups: Control (without any probiotic), probiotic (a commercial probiotic mixture-3 g/d/calf bacteria-based and 2 g/d/calf yeast-based) and kefir (20 ml/d/calf). The calves were weaned at 56 days of age. The experiment was performed in 70 days. Treatment had no effect (P>0.05) on weaning and final body weight and starter intake. Although differences in weight gain were not significant (P>0.05), there were trend to increase by probiotic treatments during 0-14 days. Probiotic treatments tended to have a positive effect on the population of the fecal lactic acid bacteria at 14 days. The results of the study indicated that kefir as a natural probiotic in calf nutrition may be beneficial during the first weeks of life.

In this study, it was aimed to determine the effects of enteritis, pneumonia and omphalitis on oxidative/antioxidant balance in the calves. In total, 27 calves with neonatal disease and 10 healthy calves (control) were used. The sick calves were divided into 3 groups according to localization of infection, omphalitis (n = 10), pneumonia (n = 8) and enteritis (n = 9). Blood samples of the calves were taken from jugular vein for analysis. Blood in tubes without anticoagulant was centrifuged at 5000 rpm for 5 min following clotting, and the sera were removed and stored at -80°C until analyzed. Serum malondialdehyde and nitric oxide levels of all groups were significantly higher, while glutathione, glutathione peroxidase, catalase and superoxide dismutase levels were significantly lower compared to the control group. As a conclusion, diarrhea, pneumonia and omphalitis are caused by oxidative damage in the calves, and antioxidant treatment may be beneficial in the treatment of these diseases.