M any factors must be considered to minimize bovine respiratory disease when feeding young calves.
Knowing the calves’ weaning times, distance transported and vaccination and health history, as well as upcoming weather conditions, will help determine the level of risk.
Each pen or group of calves needs to have a risk category ranging from low risk to ultra-high risk to determine how they could be handled.
The overall goal is to prevent a disease outbreak and high death loss by implementing management changes that will achieve top performance. Determining risk level ahead of time helps fight the pathogens to which the calves may be exposed.
The final step is making the economic calculation between preventive costs, such as vaccines, labour and metaphylactic antibiotics, versus treatment and potentially higher death loss. As with most things in farming this is a gamble, and there are always unknowns that can blindside us.
Many factors increase risk when bringing in calves or feeding your own calves, and they must be managed as successfully as possible.
Ask yourself what management changes are needed to mitigate or minimize the risk. High-risk calves for developing BRD are generally considered those presenting with one or more of these points:
- They have been commingled, either at the auction market or at home. Avoid adding more calves once a group has settled, and try to fill a pen as quickly as possible from as few original owners as possible.
- Extended transport times, where calves become stressed and dehydrated. Stress originates mainly from loading and unloading, but ultra-high risk can also result if the calves are transported over significant distances, such as when they are brought in from another province. The more local we can source cattle, the better, but it’s not always possible because calves are often raised and fed in two different parts of the country.
- Bad weather or wide temperature swings can create severe stress. Watching the weather channel may help, but you need to buy when you can. These temperature fluctuations are more likely with greater distances travelled.
- Procedures such as castration, dehorning and branding, which are done when the calves arrive, all have their stressors. The cattle industry is under scrutiny from an animal welfare perspective for these procedures, and in most cases castration is done far ahead of weaning. Polled bulls are eliminating horns, or the calves are dehorned early. Dehorning in the feedlot generally involves tipping the few horns that are left. If branding is required, minimize the size and number of characters as much as possible and minimize stress with pain killers and anti-inflammatory drugs .
- Calves recently weaned with no or poor vaccination histories. The old preconditioned programs are ideal, in which calves have already been weaned for a month. It’s best to have protection from as many respiratory pathogens as possible. This would include the viral as well as the bacterial components of the BRD complex. Don’t forget the clostridials and histophilus in your vaccination protocols.
- Lightweight calves or those that are nutritionally compromised or parasitized may also carry an additional level of risk. I think calves less than 400 pounds would be considered ultra-high risk.
Low risk calves are essentially your own calves, which are preimmunized and weaned at home into a situation where they know where feed and water are located. Weaning would occur in older, heavier calves and in good weather with either fence line or some other type of soft method. It is ideal to remove the cows from the calves and that they are familiar with the ration that they will be fed.
However, pulls for respiratory disease can climb even in these situations, and producers reach a point where treating them with antibiotics may become necessary to thwart an outbreak.
The problem with high-risk calves is what to do when you get them. Herd veterinarians will have a protocol for what they believe is best, which may vary pen to pen.
Most would consider giving the necessary vaccinations and processing and covering with metaphylactic antibiotics. The newer macrolide antibiotics last a long time in the lungs, and they are a different family from our treatment antibiotics.
The label usually states that it is for the control of BRD or to use in cattle at high risk of developing BRD. This is where knowing the risk level of calves is critical.
Feedlot veterinarians can reduce BRD incidents by assessing pens and using appropriate vaccinations.
Roy Lewis works as a technical services veterinarian with Merck Animal Health in Alberta.