Can Probiotic Supplements Reduce Beef Calf Stress?

Project Title

Using a bovine Lactobacillus mixture as a strategy to minimize beef calf stress


Gleise Medeiros da Silva (University of Alberta)

Leluo Guan (University of Alberta), Maria Camila Ceballos Betancourt (University of Calgary), Tim McAllister, Karen S. Schwartzkopf-Genswein and Nilusha Malmuthuge (AAFC Lethbridge)

Status Project Code
In progress. Results expected in March, 2024 POC.14.22


Throughout their lives, beef cattle are exposed to different sources of stress that can compromise their health and productivity. Traditionally, antibiotics have been used to treat disease and as preventative agents especially during times of high stress, like weaning. With the rise in antimicrobial resistance, other strategies are being explored to improve the health of calves by reducing stress and ultimately reducing the reliance on antibiotics.

Some probiotics have been shown to reduce stress in livestock by increasing the amount of neurotransmitters reaching the brain, which positively benefits the host. They do this by serving as a key component or precursors of naturally occurring “happy chemicals” in the brain, like serotonin, resulting in more of these hormones and a positive physical response to them. However, these neuroactive compounds (psychobiotics) may behave differently in ruminants. This project will test whether a Lactobacillus spp. probiotic mixture given at spring processing affects physiological and behavioral stress measurements taken at weaning.


  •  Evaluate the long-term effects of a bovine-derived Lactobacillus spp. mixture given at spring processing on mitigating the stress of weaning on beef calves.

What they will do

This project will be the first to combine and evaluate the effects of bovine-derived Lactobacillus bacteria (mixture of L. reuteri, L. delbrueckii, L. mucosae, and L. agilis) as a means to reduce stress in beef calves.

The study will be done at the UofA’s Kinsella Research Ranch, using 40 crossbred calves (20 per treatment) who will be randomly assigned to either receive the probiotic mixture or a placebo of saline solution at spring processing. A second dose will be administered 3 days after the initial treatment. Blood and fecal samples will be taken and behaviour will be observed (cattle reactivity and laying down/standing behaviour) to evaluate if early-life psychobiotics can reduce the stress of weaning in beef calves. The two groups of cattle (probiotic and placebo) will be pastured separately to avoid cross-contaminating each other during the first 15 days after treatment.

Blood and fecal samples will be collected four separate times – at the time of the initial treatment (baseline), at the time of the second dose (3 days after initial treatment), at the time of weaning, and 3 days post weaning when stress proteins are at their peak. At these times, a trained observer will evaluate the reactivity of cattle and standing/laying behaviours will be monitored using pedometers post-weaning, as behavioural indicators of stress.  


Reducing stress at weaning improves the welfare of beef calves during and post-weaning which can result in healthier calves who are less likely to get sick. This can result in fewer chronically ill calves pre- and post-weaning, reduce the occurrence of preventable disease and ultimately, reduce antimicrobial use. Healthier and happier calves also perform better at the feedlot by getting on feed quicker and reducing their susceptibility to disease while being intermingled with hundreds if not thousands of other calves from many different regions with many different germs.