Effect of oral administration of probiotics on growth performance, apparent nutrient digestibility and stress-related indicators in Holstein calves

This study aimed to investigate the effect of dietary supplementation with Lactobacillus plantarum and Bacillus subtilis on growth performance, apparent nutrient digestibility and stress-related indicators in dairy calves. Twenty-four neonatal Holstein calves were randomly allocated to three treatments: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 × 10(10) CFU per head per day (CFU/h.d) of L. plantarum GF103 (LB group) or the basal diet supplemented with a mixture of L. plantarum GF103 (1.7 × 10(10) CFU/h.d) and B. subtilis B27 (1.7 × 10(8) CFU/h.d) (LBS group). Dry matter intake (DMI), average daily gain (ADG), feed conversation ratio (FCR), apparent digestibility of nutrients and stress-related indicators were measured in this trail. The result indicated that no significant differences were observed in DMI or ADG (p > 0.05), but the FCR was improved in the LB group over the first 12 weeks (p > 0.05). The apparent digestibility of nutrients was not altered by probiotics in week 6 (p > 0.05), but the apparent digestibility of total phosphorus was significantly greater in the LB and LBS groups in week 8 (p > 0.05); additionally, an increase in the apparent digestibility of crude protein was detected in the LBS group (p > 0.05). Oral administration of L. plantarum alone improved the T-lymphocyte transformation rate on days 58 and 62 (p > 0.05), while adding the mixture of L. plantarum and B. subtilis increased the T-lymphocyte transformation rate (p > 0.05) but decreased the content of cortisol on day 58 (p > 0.05). No significant differences were detected between the LB and LBS groups in growth performance, apparent digestibility of nutrients and stress-related indicators (p > 0.05). The results suggested that oral administration of L. plantarum improved growth performance, nutrient digestibility and relieved weaning stress in calves, but no additional effect was obtained by supplementation with B. subtilis.