Growth Promotion and Economic Benefits of the Probiotic Lactiplantibacillus plantarum in Calves

Objectives: Various measures have been attempted to prevent infectious diseases in calves, such as environmental improvement and vaccine administration. Probiotics are commonly used to improve the body condition of newborn calves and prevent disease. In our previous research, Lactiplantibacillus plantarum RGU-LP1 (LP1) suppressed the expression of inflammatory cytokines in PBMCs of cattle fed it in the diet. In this study, we evaluated the effect of LP1 on the weights and number of treatments of the calves. Methods: Twenty-six one-week-old Holstein bull calves were divided into two groups (thirteen each), the LP1 group (LP1-treated) and the CN group (no LP1 fed), and tested as follows. The LP1 group was fed lyophilized LP1 (109 CFU/head/day) in milk replacer for 40 days. The CN group was fed the same diet only. Calves were followed for 63 days. The average treatment costs for the LP1 during the period were recorded. Feces and blood were collected from each calf during this period. Feces were examined for gut microbiota, and blood for immune assay and cytokine gene expression. Results: The LP1-treated group showed a decrease in disease incidence and an increase in body weights compared to controls. The average treatment cost during the observation period was significantly reduced compared to the CN group. The expression of TGFβ and IL10, inhibitory cytokines of inflammation, was significantly increased. The simultaneous expression of this set of inhibitory molecules resulted in low serum IL1β levels during the growth period. Conclusions: The Th1-type cytokine IFNγ was also significantly increased in LP1-treated calves. By reducing the amount of disease treatments and increasing dairy gain, LP1 is effective in preventing infectious diseases in calves. In addition, the increase in IFNγ by LP1 indicates improved Th1-type immunity in calves. These results show that LP1 has effects on the regulated inflammatory response and growth of calves.