Tooling Up to Fine Tune Indoor Environments
Minor refinements in the environment of a pork production building can make major differences in animal health and performance. But it's not a job for guesswork, emphasizes John Roberts of North Carolina State University. He has a special interest in applying simple instruments to measure environmental conditions in pork facilities.
Roberts' recommendations are based on 25 years as a swine veterinarian. Along with a private practice in Iowa, he has served as health-services manager for a large pork company and as a researcher at North Carolina State's College of Veterinary Medicine.
"Paying attention to a building's environment can avoid serious disease situations," says Roberts. "It also promotes feed intake."
Ventilation is the primary factor affecting the hogs' environment. Moving stale, moisture-laden air out of a building – and with it bacteria and pathogens – helps avoid health issues. "When there is a question about ventilation," says Roberts, "always measure air qualities to determine the
adjustments you need to make."
Humidity pen $50-$65
Temperature pen $55-$65
One of these inexpensive, dual-function tools is a useful piece of diagnostic equipment, especially during winter. When air exchange is low, humidity can build up and create stale air containing high carbon dioxide levels.
A datalogger automatically takes humidity and temperature readings every 15 minutes for several days and records them for transfer to a personal computer. The computer generates humidity and temperature graphs over time.
A desirable humidity range is less than 60 percent, with 60 percent to 70 percent requiring caution, more than 70 percent is a danger zone.
Some symptoms to watch for in pigs include increased coughing and sneezing caused by high humidity; nursery and finishing groups may lose animals from Strep.suis, Haemophilus parasuis or Actinobacillus pleuropneumoniae.
- How to use to the pens: After entering a building, allow the pen 2 to 5 minutes to adjust to conditions. Set switch on pen to read temperature or humidity. Take readings at waist level from several places in the room.
- How to use the datalogger: With a wire, suspend the datalogger about 3 feet above pig level. Leave for at least 48 hours and read measurements using computer software.
The datalogger will measure temperature within 3°F of the desired room setting.
If room air is too hot pigs will become less active, feed intake declines, pen fouling is common, pigs may pant if heat stress is severe. If room air is too cold, farrowing or nursery pigs will chill and actively pile up. Scours may result. Finishing pigs show increased piling and rectal prolapses.
CYCLING ROOM TEMPERATURE
Room temperature measurements should vary less than 5°F in an hour. Desired room temperature should be near the middle of the temperature range.
Oversized fans or improper ventilation control, such as a timer set for excessively long intervals between fan or heater operation are common problems. Sensors also may malfunction. Make sure that protected sensors are inside PVC pipes more than 3 inches in diameter. A smaller pipe takes too long for the sensor to warm up and cool down.
Affected pigs will appear anxious and stressed. Nursery pigs may display rotaviral diarrhea that recurs in subsequent groups. Finishing pigs may bite tails, especially in the fall and winter.
DAILY ROOM-TEMPERATURE RANGE
During late summer and early fall, it's not easy to control room temperatures when 24-hour outdoor temperatures fluctuate greatly. Other challenges arise when weather runs exceptionally hot or cold for long periods. During such extremes, Roberts emphasizes that extra attention to ventilation is warranted.
It is a mistake, he says, to assume that cooling mechanisms only operate when needed. During times of prolonged heat, tunnel-ventilation mechanisms and sprinkler settings require special attention. They should not be set so low that they come on at night when outside temperatures approach set points and cause chilling.
In winter, properly set heaters and fans usually maintain room temperature closely as long as correct differential settings are maintained.
The winter room-temperature range for 24 hours should be less than 15°F. In the summer, daily room-temperature ranges should not exceed 15°F for more than five consecutive days.
You can expect problems if pigs appear stressed. Also, feed intake and rate of gain declines. In nursery and finishing pigs, coughing and respiratory problems may be apparent.
ROOM TEMPERATURE VARIABILITY
Within a room at a specific time, temperature variation should not exceed 5°F from floor to ceiling or from any part of a room to another. An exception is a tunnel-ventilated building, which should not vary more than 8°F from the inlet end to exhaust end. Ventilation is incorrect if temperatures vary more than 5°F at two points in the room. Warm areas are "dead spots" containing damp, stale air.
A thermoanemometer measures either air temperature or rate of air movement. A switch determines the mode. Its thermal probe measures air temperature quickly and accurately, taking many readings at multiple points.
Choked air intake or excessive intake space, such as an open door, causes room temperature variability.
Piglets may pile during low temperatures because they are chilled. At the same time, other pigs may seem warm. Nursery and finishing pigs in some sections may appear uneasy and stressed, develop health problems – such as pneumonia, Strep. suis, Haemophilus parasuis or Actinobacillus pleuropneumoniae – while others are fine.
- How to use the tool: Set the switch to measure air temperature or rate of air movement. With wand extended, hold the end and take measurements by placing the tip of the wand in the air space of concern. When checking temperature, move through the room and take readings from floor to ceiling, corner to corner and from each end to see if all portions of the building are within the desired 5°F range.
Intake air speed between 700 and 1,000 feet per minute is desirable. Air movement at pig level should not exceed 30 feet per minute, air currents exceeding that are drafts that can chill pigs.
Intake that's too slow (less than 700 feet per minute) creates inadequate air mix, causing air to fall too quickly. Intake that's too fast (greater than 1,000 cubic feet per minute) mixes air, but the excessive speed may cause drafts.
- How to use the tool: Turn it on and allow wire on the wand tip to heat up. Hold in an air current. The wire's cooling rate is converted to an air speed. Take several readings within an air current and estimate an average. The acceptable reading at an air inlet is 700 to 1,000 feet per minute, which indicates it's neither opened too far nor too little. Check the pigs' areas to assure that air currents average less than 30 feet per minute.
SMALL AIR PATTERNS
Borozin Smoke Gun $130-$140
Smoke stick $45-$55 per dozen
Fresh air flows high against the ceiling and mixes with room air before falling. But problems occur when intake air falls abruptly into farrowing crates or onto nursery and finishing pigs' sleeping areas, causing chills. Air leaking into a building from an unplanned opening creates a draft.
- How to use the gun: Squeeze the gun's bulb to blow a "puff" of light powder into the air current and observe the flow.
- How to use smoke sticks: Break the glass tube under the cotton-wrapped portion of a stick. The tube contains mild acid that reacts with the cotton, generating a smoke plume for several minutes.
Digital Manometer $200-$225
Portable Static Pressure Gauge $90-$100
Maintaining proper static pressure assures correct air exchange. This prevents too much or too little air from entering the room. In cool weather, incoming air is directed to the ceiling. The air warms as it slows down before dropping to the animals.
With high static pressure, air currents move too fast, causing drafts and chilling pigs. When static pressure is too high and fans are turned to top speed, louvers on the interior face of some fans may snap shut and open quickly. "Snapping" shutters indicate that inlet space is inadequate to supply sufficient air volume.
When static pressure is low, air also enters the room too slowly, causing it to fall near the inlets. Slow air does not mix well, creating chills in some areas and hot, humid spots elsewhere. In winter, depressed static room pressure may disrupt pigs' sleeping and dunging patterns.
A desirable static-pressure reading is 0.025 to 0.035 inches of water (2.5 to 3.5 WC). More than 0.035 is too much vacuum. Less than 0.025 is too little.
If air exchange is poor and humidity is high, you can reduce high static pressure by increasing the inlet area. If pressure is too high and humidity is fine, reduce fan speed. If pressure is low and fans are operating correctly, reduce air-inlet space.
- How to use either tool: First, calibrate the unit to zero. Run a one-quarter inch, plastic tube from the unit's "outside" port through a small opening in the building to the outdoors. Leave the other port open to room air. The difference between outside and inside air is the measured static pressure.
Inadequate exhaust and air exchange, reduce summertime cooling potential. A motor malfunction or worn belts can cause fans to turn too slowly.
To measure rate per minute, place shiny tape on a fan blade near its end. Turn fan to full speed. Aim the tachometer's light at the rotating fan blades, and it will read the fan's rpm.
To measure fan output, turn the fan to top speed. Touch the tip of the instrument's axle to the fan's center. The rotating fan spins the axle and the instrument reads the rpm.
You also can use a thermoanemometer to measure air speed outside where the fan exhausts. Refer to a fan output chart to find the fan's rated cubic feet per minute. Divide this number by the fan's diameter in inches and again by 3.14. It gives you the air speed of the exhaust air stream in feet per minute that the fan should produce when operating at maximum rpm.
LARGE AIR PATTERNS
Insect Fogger $65-$75
Gross air flow from inlets should move across the ceiling, progress down alleyways, over crates or pens, allowing fresh air distribution throughout the room. There should be no intake-air leaks around doors or feed augers. Watch for leaks from adjacent rooms. Heaters and stir fans should be directed to complement gross air movement throughout the room.
Problems develop when uneven air intake occurs across inlet space. It results in uneven air distribution in the room, leaving damp, stale air in "dead spots." Another problem is excessive air movement in pig-occupied areas.
- How to use the tool: Turn on butane and light the burner around the coil. Pump oil through the coil to generate smoke. Direct smoke billows into a part of room to watch the air current. From outside the building, smoke can be "pumped" into inlets. Another person indoors can note air intake evenness and flow patterns.
PIGLET MAT TEMPERATURE
Infrared surface thermometer $100-$125
Mat surface temperature should be between 95°F and 100°F. When a mat is too hot, piglets avoid it and lay near the sow instead. When a mat is too cool, pigs lay next to the sow to keep warm. Either condition runs the risk of the sow crushing piglets.
A mat gets too hot when a heat lamp is set too close or the bulb is too large. A mat is too cold when the heat lamp is suspended higher than pen dividers and air current dissipates the heat.
Piglet crushing is a signal that something is wrong. Newborns that are inadequately warmed in the first 24 hours are less likely to nurse and thrive. Also, chilling often results in diarrhea.
- How to use the tool: Aim the end of the device or its laser pointer at the mat. Attempt to measure a 6-inch circle under the lamp. The mat surface temperature appears as a digital reading. The farther away from the mat the device is held, the larger the surface area included in the measurement.
Where to Go for Help?
John Roberts purchased the instruments shown in this article from the following vendors:
- Animal Environment Specialists, 11951 Rausch Rd., Marysville, OH 43040. Phone (937) 642-4690; fax (937) 642-4690; e-mail firstname.lastname@example.org
- Cole-Parmer Instrument Co., 625 E. Bunker Court, Vernon Hills, IL 60061. Phone (800) 323-4340; fax (847) 247-2929; e-mail email@example.com; Web site www.coleparmer.com
- Dwyer Instruments, 102 Highway 212, P. O. Box 373, Michigan City, IN 47361. Phone (800) 872-9141; fax (219) 872-9057; e-mail firstname.lastname@example.org; Web site www.dwyer-inst.com/
- Fisher Scientific, 1801 Gateway Blvd., Suite 101, Richardson, TX 75080. Phone (800) 766-7000; fax (800) 772-7702; e-mail fishersci.com; Web site www2.fishersci.com/main.jsp