Protecting preweaned calves from the elements of winter requires a tightrope walk between providing comfortable shelter, and impeding air quality, according to Geof Smith, North Carolina State University Professor of Veterinary Medicine.
On a webinar sponsored by DairExnet, Avoiding Disease in Dairy Calves, Smith noted efforts to block calves from wind and cold can go awry if they alter ventilation, which can produce poor air quality and more cases of pneumonia.
“This happens a lot in calf barns, especially in former poultry or swine barns that have been retrofitted for calves,” said Smith. “To block the elements, the sidewall curtains are closed completely, and the air quality gets really bad in a hurry.”
Regardless of the type of housing, Smith said it’s important to pay attention to the microenvironment of the calves, not just your personal impression. The air quality at your height might be excellent, but that may not be the case 2 feet off the ground, where the calf lives and breathes.
Smith advised the following measures to promote winter air quality and prevent pneumonia in various calf housing systems:
- Indoor barns with individual pens – Prevent nose-to-nose contact with solid-panel pens that are open in the front and back for air movement. Even in extremely cold conditions, leave sidewall curtains at least partially open and protect calves with deep, organic bedding. Smith referred to the University of Wisconsin’s nesting score system, advising that calves in cold conditions should be bedded to a nesting score of “3,” meaning the bedding is deep enough so you can’t see the calves’ legs.
- Individual hutches – Hutches provide natural ventilation and protection from winter elements, but Smith said you can run into trouble if they are crowded too closely together. Even if done with the best of intentions of sheltering hutches from the wind, stacking them too tightly together can promote disease transmission between calves. An easy rule of thumb is to position hutches so there is at least one hutch-width between units.
- Group pens – Group-housed calves will automatically have nose-to-nose contact, so Smith said their respiratory health needs to be protected via other measures. Deep organic bedding and ventilation with fresh (not recycled) air are important. Stocking density should be 20 calves per pen or less, with resting space of 4 square meters per calf or more.
In all housing settings, written protocols for disease detection AND treatment -- prepared with the herd veterinarian -- should be in place. “Calves will respond much better to treatment if they are diagnosed early,” Smith advised. He recommended two helpful calf health monitoring systems: the University of Wisconsin’s Calf Health Scorer app; and the California BRD Scoring System app from the University of California-Davis.
Smith cautioned that colostrum management, housing and early detection all are more important than drug therapy, as there are no “silver bullets” that will automatically keep your calves healthy. He said there is real cause for concern and veterinary intervention if you are treating 20% or more of your preweaned calves for respiratory disease.
When drug therapy is needed, “having treatment protocols in place will ensure calves receive consistent, veterinary-prescribed therapy, regardless of who is working the day the calf is detected ill,” advised Smith. “An accompanying monitory system also will help you and your veterinarian determine over time whether or not a specific treatment is working.”