Promoting health, growth and well-being of dairy calves is vital to ensure the future of the lactating herd. Thus, preserving their health becomes essential, as it directly contributes to boosting their immune system and maximizing nutrient utilization. Therefore, the objectives of this research were to 1) evaluate the impact of tyndallized Lactobacillus helveticus (TLH) supplementation on growth and health metrics during the pre- and post-weaning period to Holstein calves, and 2) to evaluate if supplementing TLH can mitigate the adverse effects of an abrupt weaning model on gut barrier function and inflammation. Data from Chapter 2 demonstrates that TLH supplementation improves feed intake in the post-weaning period and tends to improve growth, whereas Chapter 3 suggests that TLH leads to a reduction in blood inflammatory-related markers. Based on these data, the use of TLH could enhance the recovery of calves exposed to abrupt weaning practices, promoting their health and performance.