BRD risk categorization for feeder calves - part 2

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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.
  • Parasitism.

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.

R-1.  Rest and Recuperation

Calves should be closely inspected upon arrival for their physical well-being. Early treatment of sick or injured calves should be provided. They should be handled in the least stressful manner as possible and placed in a clean, dry, isolated and easily accessible pen and provided the appropriate weather protection for the season. Holding pens should have 150 to 200 square-feet of pen space per animal and 12 to 16 inches of bunk space per animal and located close to the processing facility. These calves should be allowed to rest for up to 24 hours prior to further processing. Frequent inspection to access behavior, appetite, water consumption, and health status should be provided. Quiet movement around and through the pen may be necessary to adapt the calves to human handling. The objective is to allow recuperation, reduction of stress and recovery of immune system function. 

R-2. Rehydration

Clean, readily accessible drinking water should be available. Ideally, the watering system should provide fresh, flowing water and be placed in the fenceline. Newly received calves generally walk the perimeter of the pen for some period of time and will find the water source during their passing. Addition of water-soluble electrolytes or medications should be avoided until assurance that the calves are drinking adequate water for rehydration and shrink recovery.

R-3. Rumen Restoration

Depending on the time in transit, calves will lose body weight –shrink- and have a disruption of rumen digestive activity. Metabolic needs for energy, protein and essential vitamins and minerals will need to be restored via reactivation of rumen microbial digestion. Initially, fresh and high quality dry hay should be provided to entice appetite and provide effective fiber for rumination. Hay should be limit-fed in feed bunks or racks with small quantities of hay on the ground in the pen. Free choice access to hay is discouraged as it limits the ability to assess appetite and health of individual calves. Trace mineralized salt may be offered ad lib to the pen. Within 6-18 hours, a high quality, highly palatable and concentrated (>50% concentrate) starter ration should be offered in limited amounts (0.5 to 1.0% of body weight) by top-dressing on a small amount of hay. Self-fed rations again would be discouraged. The receiving feeding program and rations should be formulated with the aid of a qualified ruminant nutritionist. The objective is to restore the metabolic status of the calves, activate the digestive process and initiate the detection of sick calves.

This is a very general review of “best management practices” which is applicable for receiving all feeder calves with the recommendations being especially crucial for high-risk calves. Further health management practices in the form of vaccinations, treatments, parasite control, other medications and procedures should not be delayed past 48 hours following arrival under most circumstances. The objective of the 3R’s is to allow the calves to rest, recuperate and recover function of their digestive and immune systems and optimize the effectiveness of the other preventative health measures. The basic 3R’s go a long way in helping to reduce the BRD wrecks that often loom for high-risk feeder cattle. In the words of a song from the past – Try a Little Tenderness! 

Source: Roger Ellis, DVM


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