Weaned calves in the preconditioning or backgrounding pen should have come in with a plan. For those happy with weanling prices, calves in the pen may be limited to replacement heifer prospects. Others may see this as a year to retain ownership through finishing, or you’re just waiting to sell calves in a new year. No matter why you’re feeding those calves now, you face significant challenges from respiratory disease (BRD). Even fall-born, nursing calves are at risk with the fluctuating temperatures and frequent changes in weather.
How can you tell if calves are coming down with this disease? A recent article in the Journal of Animal Science from Dr. Rachel Toaff-Rosenstein and veterinary co-workers at the University of California – Davis summarizes. Coughing, wheezing, nasal discharge, gauntness, listlessness, anorexia and fever are a few of the 21 BRD symptoms observed. Unique to this study is the reported grooming behavior of steers in the study.
Contrary to what most ranchers believe, the fever response to an infection is a necessary and beneficial component of sickness behavior. It reduces the infecting microbe’s reproductive ability, which lets the animal overcome the disease. Still, the “energetic” cost of fever is high, as an active immune system uses a lot of energy. Figure in the reduction in feed intake associated with fever and you get an environment where the steers need to conserve their energy.
The authors hypothesized there would be less grooming as expressed by licking and scratching, and observing that could provide more insight into early sickness detection.
Calves were challenged with several diseases including multiple BRD strains, and then a clinical illness score was assigned using the symptoms described above. In addition, grooming behavior was recorded to see if steers used an automated brush or licked their hair coat. Contrary to their hypothesis, they found no correlation to grooming behavior and BRD onset or severity.
Observations did confirm usefulness of past diagnostic tools, however. Clinically ill steers exhibited a nearly 2ºF greater fever and spent 35 percent less time eating than healthy calves. The efficacy of fever and its magnitude in fighting disease was not tested, but it was confirmed as the calf’s first disease response. It was documented that as disease progressed, temperature increased beyond the normal 101.5ºF and exceeded the 103ºF treatment threshold temperature.
That predictable temperature increase to the treatment threshold offers consistency in treatment protocols. Animals have a variable “normal” temperature that fluctuates with the environment, so it’s best to work with your local veterinarian to determine the treatment program and post-treatment intervals before re-treating.
Spending 35 percent less time eating fits in with previous work that showed ill calves ate less often than well pen mates. The fact hasn’t changed, but it is more significant now, given the changing rules on use of feed-grade antibiotics. If you plan to feed antibiotics to treat calves, keep in mind the target animal eats less than healthy cattle, resulting in a poor treatment response and marginal prevention of BRD.
Since prevention really is key, perhaps the take-home from the California study is the mandate to observe calves for signs of illness and start by monitoring animals at the bunk for feeding behavior. If you have trouble finding enough time to watch them eating, consider closing off the automatic waterer and set up a tank – just make sure to monitor it! Waiting on the water tank to fill provides plenty of time to observe calves while providing clean water.
If you think your time is too valuable to watch for symptoms, remember the Tri-County Steer Carcass Futurity (TCSCF) data demonstrates calves that need treatment for respiratory disease rack up more than $70 in carcass discounts, while those needing treatment twice cost more than $300 compared to healthy steers. The cost of lung damage to future replacement heifers is difficult to determine but certainly could change a keeper to a cull.
We know respiratory illness saps profit at any stage of the beef production system. TCSCF data suggests calves that get sick one time are significantly less profitable, while those that are treated two or more times are several times less profitable in that terminal system. Logically, our replacement heifer prospects that had an early bout of BRD could face limited productivity in hot weather because any lung damage would reduce respiration ability in the adult cow.
Justin Sexten is the supply development director for Certified Angus Beef.
—From Certified Angus Beef November 2016 “On Target” column