NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
April 30, 1998
No sweat for you means no stress, but for pigs, no sweat can mean big trouble during warm weather.
"Because swine lack the ability to sweat, producers need to take temperature, humidity, and housing conditions into consideration when providing comfortable conditions for their animals," notes Bob Harrold, a swine researcher at North Dakota State University.
Current management guidelines suggest that some form of cooling system is needed for pigs when temperatures climb beyond 90 F. But Harrold suggests that producers may need to take action at lower temperatures. "High relative humidity makes it more difficult for swine to cool themselves," Harrold says. "If relative humidity is high, lower temperatures will be uncomfortable for swine."
And uncomfortable pigs are unproductive pigs he notes. Heat stress can cut feed intake and feed efficiency of growing-finishing pigs and make them susceptible to disease problems. In breeding stock, heat stress can lead to the same health concerns and result in fertility problems.
Pigs under heat stress may play with watering devices to develop a wet area for wallowing. They may also stretch out on bare concrete or exhibit irritable behavior.
"During hot weather, all pigs need an opportunity to moisten at least some of their skin," Harrold says. "As that moisture evaporates, it cools the animal."
Drip lines over sows in farrowing crates are commonly used to cool sows. Air movement at the level of the sow's snout is another method of providing some relief for the sow during hot weather.
Very young pigs have an optimum temperature of about 95 F because they can't effectively control their body temperature shortly after birth, Harrold notes. That means producers should not allow too much moisture or air movement to reach baby pigs.
Newly weaned pigs are often started at temperatures of 85 to 90 F and the temperature of the nursery may be reduced by 2 to 3 degrees each week. The optimum temperature for growing-finishing pigs declines to about 65 F as the pigs near market weight. Older pigs may be cooled by having a drip area in the pen or by providing a timed spray of water for one minute in each 15 minutes. A constant spray wastes water and doesn't allow water to evaporate and cool the animals.
Some portions of pens housing growing-finishing animals should be kept bare because concrete can serve as a heat sink and draw heat from the animals, Harrold notes.
"Adequate drinking water is an obvious consideration during warm weather," Harrold notes. Younger pigs from weaning to market weight will consume about a third of a gallon of water per pound of feed consumed under normal conditions, and consumption will increase in hot weather.
To help young pigs learn to use a nipple waterer, Ron Zimprich, NDSU swine herdsman, places a piece of tape on the valve to provide a steady drip of water. After a day or two, the tape can be removed because the pigs have learned how to use the drinker.
Normal water consumption for breeding stock can vary from three gallons per day for open gilts to five to seven gallons per day for boars, gestating sows and gilts, and lactating sows. Drinking nipples or bowls should be checked regularly and any sediment cleaned from bowl drinkers at least daily to maintain fresh water and encourage water intake.
Despite these measures, heat stress may cause feed intake to drop. If that's the case, Harrold advises modifying rations to ensure that nonenergy nutrients such as protein, amino acids and minerals should be increased in an attempt to maintain the amount of those nutrients pigs consume each day. "If we reduce intake of the nutrients needed for muscle development it will lead to decreases in the rate of muscle growth," he explains.
Source: Bob Harrold (701) 231-7659
Editor: Tom Jirik (701) 231-9629