By Steve Beadle, P. Eng., OMAFRA
Good indoor air quality is critical to the health and performance of goat kids. Indoor air quality is controlled, in part, by ventilation systems. A ventilation system must:
- provide fresh air without causing drafts;
- maintain reasonable temperature and humidity; and
- exhaust contaminants like ammonia to the outdoors.
Natural ventilation systems use wind and thermal buoyancy (cold air lifts warmer air up and out of the building) to exchange the air within the animal housing. Mechanical ventilation systems use fans to draw air out of the barn (a negative pressure system) or push air into the barn (a positive pressure system). Fans are coupled with appropriately sized and located air inlets or outlets. In both types of systems, supplementary heating appliances are used during the colder times of the year to maintain appropriate indoor air temperature while ensuring enough air exchange to exhaust contaminants and control humidity.
Consider purpose-built housing separate from the herd for dairy kids from birth to weaning. This arrangement allows better air quality management to match the specific needs of young goat kids. The type of ventilation system required depends on climate, geography and barn layout. The following sections describe some of the systems available to producers.
The purpose of the summer ventilation system is to remove excess animal heat from the barn. The required ventilation rates can be as high as one air change per minute.
Natural ventilation systems generally rely on wind during the summer months. Curtains or moveable panels on the sidewalls of the barn can be effective, provided the barn can be sited to take full advantage of summer winds. Chimney fans can be effective where housing isn’t ideally placed or upwind obstructions exist. Consider installing chimney fans with variable speed motors to exhaust the hot barn air and draw fresh air in through the sidewall openings.
In the winter, the ventilation system generally removes moisture and contaminants like ammonia from the barn. The minimum ventilation rate should be at least four air changes per hour.
In a naturally ventilated housing, thermal buoyancy carries warm, moist, contaminated air out through the chimneys. Fresh air enters through inlets at the eaves. The challenge with dairy kid housing is that young goats may not provide sufficient heat to maintain air flow or reasonable indoor air temperatures. In these cases, supplemental heat can maintain a good indoor temperature and may help maintain air flow. Radiant type heaters provide an excellent environment by heating objects like bedding (rather than the air) where young stock can get the most benefit.
Chimney fans with variable speed motors can be used where minimum ventilation rates cannot be maintained through buoyancy alone. However, negative pressure ventilation systems at very low airflow rates can have difficulty generating good airflow patterns in the barn without creating drafts.
Alternatively, consider a Positive Pressure Ventilation Tube (PPVT) system to provide fresh air directly above the pens. PPVT systems consist of a wall-mounted fan that draws outside air into the barn. The fresh air is distributed through a properly designed tube of polyethylene, vinyl, or rigid duct. The duct has strategically sized and located holes to ensure air speeds entering the barn space are less than 50 feet per minute to avoid drafts on the animals. As the room is now pressurized, appropriately sized outlets are needed to allow stale air to escape the barn. These systems have been successful in dairy calf barns.
Spring & Fall Ventilation:
Spring and fall are the most challenging times of year due to large swings in outdoor temperature and humidity between day and night. Ventilation systems may need to switch between heat control (like summer ventilation) and moisture control (like winter ventilation) throughout the day. Depending on the stocking density and age of kids, PPVT systems and supplemental heat may be sufficient to maintain appropriate ventilation rates and indoor air quality.
Regardless of the ventilation system used, this is the time of year where automatic ventilation controllers can be invaluable. These systems continuously monitor the indoor environment and adjust fans, sidewall curtains, and heaters to provide consistent indoor conditions. Automatic controllers are typically temperature-based, and rain and wind sensors are also available.
Natural ventilation, chimney fans, Positive Pressure Ventilation Tubes, or a combination of these, can properly control the indoor air quality in dairy kid housing. Ensure that the systems chosen can accommodate the wide range of air exchange rates required throughout the year. Consider installing radiant type heaters in colder climates and install automatic ventilation controllers to provide consistent indoor conditions. See Ontario Goat’s “Best Management Practices” for ideal environmental conditions for kids and contact your local ventilation supplier to discuss options for your operation. Speaking with other producers about what works and does not work on their operation is also invaluable when designing or modifying kid barn ventilation.