Previously, a risk categorization protocol was detailed on iGrow that is based upon the potential for morbidity (sickness) and mortality (death) in feeder calves (See: BRD Risk Categorization for Feeder Calves: Part 1). This addresses Bovine Respiratory Disease (BRD), which is the leading cause of morbidity and mortality through the first 30 days following arrival to feeding programs. As widely documented in research and field reports, calves meeting the criteria of “high-risk” experience increased disease incidence, costs, and profit losses.
What levels of BRD are commonly expected with “high-risk” feeder calves? Reported incidence rates for calves treated for BRD regularly exceed 15% and often are greater than 50%. Death losses greater than 2% and case fatality rates greater than 20% are commonly experienced. Chronic BRD cases (non-responders to treatment) may exceed 25%. BRD at these reported levels has devastating economic and emotional effects on stocker and feeder operators. The challenge remains to understand these risks and implement sound health management programs to minimize the losses.
Many contributing factors have been identified which increase the risk for BRD in weanling calves. Within the established marketing avenues, calves are exposed to environmental and management stressors and challenged by infectious agents that are associated with BRD.
Factors associated with BRD in calves (Acquired Factors)
- Weaning stress.
- Handling and transportation stress.
- Movement through cattle markets or congregating facilities.
- Commingling of calves from multiple origins.
- Delays in direct movement to the feeding operation (“holding”).
- Excess shrink (body weight loss) during transit.
- Weather stressors.
Conditions as nursing calves associated with BRD (Pre-existing Factors)
- Immunological deficiencies (insufficient colostrum-derived immunity).
- Previous disease (nursing calf health problems).
- Presence of PI (persistently infected) BVD calves.
- Lack of or insufficient pre-marketing vaccinations for BRD agents.
- Failure to castrate bull calves and dehorn nursing calves.
- Nutritional deficits or imbalances.
Designating newly received feeder calves as “high-risk” should heighten the level of management upon arrival. Cattle that have shrunk more than 7% can be assumed to be highly stressed and at high risk for health problems. A designated receiving program should be established with the guidance of your herd health veterinarian. Specific BRD prevention practices are recommended and have been widely utilized. However, before all the recommended procedures (vaccinations, treatments, supplements, etc.) are implemented, the basic “3 R’s” of the receiving program (Pollreiz, 1995) are most crucial.