The aim of this study was to monitor the effect of Bifidobacterium bifidum (BB) and the combination of Lactobacillus sporogenes, Enterococcus faecium, and Bifidobacterium bifidum (LEB) on the health status and weight gain of calves, and the utilisation of nitrogenous substances. The experiment was performed in the period from April 2020 to September 2020. A total of 90 Holstein heifers, which were one to 56 days old, were used as experimental animals. Differences in live weight gain were significant if we compared the LEB vs. BB group and the LEB vs. C, the control group (86.23 ± 5.49 kg vs. 84.72 ± 6.22 kg, p < 0.05; 86.23 ± 5.49 kg vs. 82.86 ± 5.35 kg, p < 0.01). Considering the live weight gain, group BB was heavier than group C only (84.72 ± 6.22 kg vs. 82.86 ± 5.35 kg, p < 0.05). An effect on reducing the incidence and duration of diarrheal diseases was not demonstrated in this study (p = 0.1957). The administration of feed additives had no statistically significant effect on the amount of N excreted in the feces. The values of hematological and biochemical parameters were unaffected except for the first sampling of urea. Other blood parameters were not affected by the addition of probiotic feed additives. The bacterial populations in the feces 5 days and 56 days after birth were not affected by the inclusion of feed additives.
Keywords: blood parameters; dairy calves; diarrhea; feed additives; probiotics.