During different parts of the year producers have many creative and practical solutions to animal housing. Living in Pennsylvania, winter is the focal point for producers to pay maximum attention to housing details. During this time is when animals are moved to a more confined housing situation, with limited access to a dry lot for exercise. In consideration of that fact, it’s important to not only consider if there is enough floor space, bunk space, feeding space, and lighting, but also if there will be adequate ventilation.
According to Carol Delaney, who is the Small Ruminant Dairy Specialist at the University of Vermont, optimal airflow should be around 4-15 room volume air exchanges per hour, or 20 cubic feet per minute per animal. This means that while you’re working in the barn doing chores for an hour, the air in the building should have exchanged with fresh air between 4 and 15 times. This amount of air flow will be enough to adequately remove the stagnant air, but not so much that it causes drafts and reduces the temperature of the housing to drop below optimal standards of 50-60°F for adults and 54-65°F for the young (Delaney, p.1).
If optimal air flow is not achieved, the environment inside the barn will accumulate higher levels of airborne pathogens, dust particles, moisture, gases (such as ammonia), and heat. During the winter months most producers will choose to bed pack their manure inside the housing structures to help insulate and warm the barn. Some of the disadvantages to this type of system if the ventilation is poor would be if the bed pack is not taken care of properly it will release more moisture and there will be a buildup of ammonia and other gasses from the breakdown of fecal material. The environment that exists with poor ventilation is perfect for respiratory disease.
The most common respiratory disease observed in sheep and goats is pneumonia, which can either be bacterial, viral, or caused by a parasite. In consideration of the above conditions that occur due to poor air flow, this type of impure air contributes to mainly bacterial pneumonia infections.
According to Delaney, pneumonia is progressive, chronic, or acute in its infliction. Even after successful treatment of pneumonia, underlying damage will remain in their respiratory tracts. Sheep and goats that are processed and have had a respiratory disease sometime during their life will show scarring, discoloration, and in severe cases the lungs will be deformed and ‘pasted’ to the rib cage. Animals that are not lost will always have this hindrance and tend to be poor producers, lack efficiency, and end up on the cull list. For breeders, especially those with smaller herds, this can claim a significant portion of breeding or replacement stock and have a heavy economic impact.
If you find when walking into your housing structure there is a strong smell of ammonia, an accumulation of condensation on the walls and ceiling, or you notice there is excessive coughing and/or nasal discharge coming from your animals, you most likely have poor ventilation.
Poor ventilation can be remedied by either incorporating natural ventilation through a cupola, gabled roof with eave openings, utilizing curtain walls, or through mechanical means with fans. In any case, proper ventilation should remove odors and gases, distribute fresh air proportionately, and remove respired moisture in the environment.
Proper airflow in small ruminant housing in the winter is just as important, if not more so, than having a housing facility at all. Improper airflow can cause more economic loss in a herd through long- and short-term respiratory disease than having just the basic shelter for sheep and goats to get covered during the worst of the winter weather. However, if proper airflow is achieved in your facility, it will decrease the amount of cold and weather stress an animal will endure over the winter. Minimizing stress during winter reduces nutritional maintenance requirements. In turn, this results in higher profits.