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 1.7x10(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 (1.7x10(10) CFU/h.d) and B.subtilis B27 (1.7x10(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 12weeks (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.