Bovine respiratory disease (BRD) remains a common challenge and source of loss in calf raising. BRD typically arises from a misbalance between:
- Stress, which compromises the calf’s immune system – stress can reach high levels when weaning occurs in conjunction with re-grouping and ration changes
- Pathogen exposure – often increases with re-grouping at weaning, but can occur any time calves are exposed to other calves (especially sick calves, those of a different age, or from other farms)
Whether a calf develops BRD is influenced by risk factors similar to other diseases, including diarrhea. The calf requires early immune protection from colostrum and sufficient nutrition to for growth and development. However, BRD is also heavily influenced by the environment. While housing and ventilation are critical, it can be particularly frustrating to have to manage BRD outbreaks in the face of fluctuating temperatures.
New Research
Often by the time BRD is identified, irreversible damage has been done to the calf’s lungs. Beyond the cost of treatment, this lung damage can result in many indirect costs due to decreased growth, increased mortality, and increased age at first calving and risk of dystocia in heifers. Recent research by Amy Stanton from the University of Guelph reinforces the long-term negative effects of BRD, such as:
- Decreased average daily gain (ADG) up to 9 months of age (and a 30kg difference in weight past this age)
- Increased age at first calving. The median age was 2 weeks older
- Some farms, which have low culling rates for BRD calves, showed decreased milk production at the first milk test
This work also investigated the effect of administering a long-acting antibiotic at weaning for prevention of BRD. Data showed that this treatment reduced the risk of developing BRD in the post-weaning period, resulting in better health and performance (Stanton et al. 2010). However, only calves that did not have BRD prior to treatment benefited from the effect of treatment, emphasizing the importance of early prevention. Prophylactic antibiotic use may have a role in getting ahead of outbreaks during periods of high risk (such as temperature fluctuations), but should be used in conjunction with best management practices and after consulting with your veterinarian.
Prevention
If you are experiencing an ongoing, high incidence of BRD, work to identify causative agents and other risk factors such as poor ventilation and housing. Stanton also presents the following prevention strategies to give calves the best start:
- Move the calf from the dam into a separate barn, preferably within 12h but not longer than 24h, to prevent spread of pathogens from cow to calf
- Use a local anesthetic with some analgesics to help reduce the stress of dehorning
- Make sure calves are ready to make that transition from milk to calf starter (A good guideline is to ensure they are consuming one to two pounds of calf starter for several days before you remove the milk)
- Ensure ample fresh, clean drinking water to help stimulate the calf starter intake and rumen development
It is particularly important to minimize stress at weaning; even if calves do not experience BRD, stress can yield other negative effects, likely resulting in a growth slump post-weaning. It is recommended to minimize and spread out stressors that have traditionally occurred all at once during weaning. When possible, individually housed calves could be introduced in small groups and to new feed before being moved to a larger group.
Consider how you can minimize BRD in your calves to ensure their best growth and future health.
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