Practice Tip: Calf ranches and respiratory disease

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Calf ranches typically raise day-old Holstein calves up to several hundred pounds in preparation for entry into the feedlot. “The task is specialized and demanding with death loss being a constant threat,” says Bob Glock, DVM, PhD, University of Arizona Veterinary Diagnostic Laboratory. “Environment/sanitation is critical. High death losses often trend directly with the weather.”

Glock discusses some of the major challenges for calf ranches:

  • Most producers monitor passive transfer only sporadically to get an idea of the overall condition of calves from various suppliers but many try to design their system to keep calves alive even with minimal passive immunity. That involves dedication and attention to details such as nutrition, environment and a health program. Many producers simply can’t alienate source dairies that aren’t doing a perfect job, but rather try to work with them.
  • A frequently under-rated but essential need is a good relationship between the calf ranch and a veterinarian to initiate health planning including management, vaccine programs and treatment protocols rather than reflex reaction to high death loss. A regular program to monitor losses through necropsies, diagnostic workups when needed and records is a key to success. “The veterinarian and the nutrition expert can make the difference between success and failure as well as helping protect against inappropriate use of pharmaceutical products,” Glock says.
  • Good nutrition is essential. The veterinarian needs to be able to serve as or work with a nutritional consultant to maintain good rather than cheap rations. Weak calves don’t survive, especially when stressed. This is where least-cost may be most-expensive.



Diagnostics

Glock offers these suggestions for diagnosing and monitoring health issues on calf ranches:

Consider some type of BVD PI monitoring, suggests Glock. One approach is to test a certain number of calves from each source dairy to see if there are PI calves. “We see PIs even from dairies with a good BVDV control program,” he notes. Another approach is to monitor PI status of dead calves. If positives are found, one option is to handle incoming calves from affected sources differently with isolation. “Horizontal transmission is suspected to be very important in closely housed calves. BVDV PIs seem to frequently terminate as bacterial pneumeonias.”

Otitis with head-tilt or droopy ears is common. The most common findings from ear swab (select ruptured drums?) are Mycoplasma bovis and Pasteurella multocida, Glock says. These can carry through and exacerbate during the feeding period. Once convinced it’s probably not much benefit to do repeated cultures. Prevention is difficult.

Bacterial infections are frequently respiratory and the best way to monitor is through necropsies to determine whether lesions are respiratory or systemic. Mycoplasma bovis are frequently present. Their role is often uncertain but pretty much respiratory and linked with bacteria such as Pasteurella multocida or Mannheimia hemolytica. Cultures confirm the bacterial component and sensitivities may be helpful. Salmonella are frequently involved and may be respiratory as well as systemic.

Differentiate between Mycoplasma spp.  “There are now specific PCR methods so talk to the lab to get these done,” Glock says. “We no longer have to squint at colonies and try to guess. If it is not M. bovis it’s difficult to take it seriously.”

Dealing with Salmonella. These calves have frequently been over-exposed to antibiotics so try to sample less-treated calves. The likelihood of isolating the key pathogen (especially Salmonella spp.) is improved. Always do back-up histopathology to confirm or throw suspicion on the culture results.

“When Salmonella is involved, have the lab do serogrouping, Glock says. “Serotyping takes so long that you forget why you wanted it. If it’s serogroup D and there are systemic lesions, it’s almost certainly S. dublin.” Differentiating the other serogroups is less meaningful but serogoup will suggest which of the more common serotypes may be involved such asS. typhimurium in group B.

When doing sensitivity testing, sample several animals and look for trends. “We can often look at Salmonella sensitivities and guess which antibiotics are being used/overused in the facility,” he says.



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