It’s hardly surprising that many producers see their greatest frequency of bovine respiratory disease (BRD) cases in the winter. The transition to cold, wet conditions with large fluctuations in temperatures bring physical stress and closely packed herds where animals will hide their symptoms and share diseases. However, cold temperatures are no excuse to just treat, record and move on.
Cattle don’t get sick just because the temperature drops. Cattle can adapt to most winter conditions with a little help from a dry and sheltered facility. Healthy cattle can handle temperatures as low as 32 degrees without sacrificing energy to maintain body temperature. They’ll need more energy overall, but if their health and nutrition program have been strong, an animal’s “stress-free” zone will be able to compensate for most non-severe weather events.
BRD breakouts tend to have roots earlier in the life cycle. A nutritional imbalance from a poor or unpalatable ration, poor colostrum immunity passed on from the cow or lack of protection from an incomplete vaccination program will follow an animal through its entire life. To complicate matters, the calf’s natural passive immunity will be waning at this time as the stress of weather, feed and social realignment will be detracting from the ability of the calf to respond to disease. Controlling winter BRD is about managing these factors up front, through vaccination and nutrition, not after symptoms set in.
That said, circumstances beyond the producer’s control will contribute to the severity of a BRD event. Seasonal transitions to low or sustained cold temperatures are stressful for the animal and will affect the calf’s ability to respond to normal levels of pathogens. A damp coat from snow or heavy fog can reduce an animal’s stress-free zone by as much as 30 degrees. Crowding for warmth increases the spread of pathogens, which will find and exploit the weakness of any less healthy animals.
Once symptoms set in, the immediate remedy is to catch them early, treat and create the most comfortable isolation area possible for recovery, but that’s not the end of the story. Remember, records are more than a way to track withdrawal times. They are an archive that you and your veterinarian must learn to interpret. Find patterns, recognize life cycle issues and identify opportunities to manage outbreaks before they start. Effectively mining this data may help significantly improve the overall health of your herd and success of your operation year round.