Third in a series

Heat stress affects the physiology and metabolism of swine. It leads to decreases in appetite and growth rate. It also hampers their digestive capacity and leads to a reduction in lean tissue.

When summer arrives, the impact of heat stress can hurt herd performance as much as any viral or bacterial infection.

But with sufficient preparation and a few simple strategies, heat stress can be managed effectively, making it possible for pigs to live more comfortably and reach their full potential, several experts say.

“It’s making sure that the basics are correct – the food, the water and the air,” said Emily McDowell, DVM, a veterinarian at Pipestone Veterinary Services in Pipestone Minnesota. “It’s making sure the water flow is good and the evaporative cooling sprinklers are set appropriately.”

Here are a few suggestions for preventing heat stress in pigs:

1. Do a thorough check of your air and ventilation system

Jay Johnson, PhD, a research animal scientist with the USDA, said a study he helped conduct a year ago found that an 11 percent reduction in air flow in the pen led to a 0.42°F increase in body temperature. That in turn was accompanied by an estimated 6 percent reduction in efficiency in the pigs, he added. [1]

“One of the simplest things to do is make sure ventilation and air flow are maintained,” said Johnson, an expert in the stress physiology of swine.

The evaporative cooling sprinklers and fans are critical to maintaining air flow. The fans are the principal instruments for pulling out the hot humid air and replacing it with cooler, dryer air. McDowell said it is important to ensure that the fan blades have been cleaned, and the fans are plugged in and working. In addition, she emphasizes checking the emergency curtain drops, backup equipment and generators to make sure they are in good working order.

“Make sure that what you have works,” added Tim Safranski, PhD, a professor of animal science and state swine breeding specialist at the University of Missouri. “Make sure the fan blades are clean.”

Producers should do these checks and make necessary repairs in advance, long before the heat sets in, he said.

McDowell also suggests setting misters and sprinklers on timers that cycle on 10 percent of the time when the room temperature rises to 15°F to 20°F over the set point.

2. Check your water supply

McDowell encourages producers to monitor their water sources daily. This is particularly true for producers receiving new pigs from other farms. Before they arrive, make sure there is enough water and that all the sources are adequate and functioning properly. She recommends one nipple waterer to 10 pigs in each pen, a minimum flow rate of 2 cups (16 oz) per minute for pigs that weigh less than 50 pounds and 1 quart per minute for larger pigs.

Producers should have approximately one nipple waterer to every 10 pigs in each pen; nipple bar height should be adjusted to the height of the pigs’ shoulders. Reduce the water pressure when receiving isowean pigs so the pigs don’t get sprayed in the face when trying to drink. Cup waterers should also be cleaned frequently.

3. Schedule feeding and other activities for the cooler hours

Reducing the movement of the pigs during the hottest part of the day is a crucial part of combatting heat stress.

Elizabeth Ferry, an extension educator with Michigan State University, says activities that disrupt pigs, such as feeding or checking the pens, should be completed during the coolest times of the day.

Safranski said producers should take into account seasonal and daily patterns before deciding on feed times.

“Rather than feed at 8 a.m., a lot of times in the summer we will start earlier,” he said. “We’ll also consider night feeding. In the farrowing house, we’ll consider leaving feed overnight. Sometimes the sows will not get up until it cools down. We will try to do any movement late at night or early in the morning. Sometimes we’ll come back at 8 or 9 at night or first thing in the morning.”

References:

[1]. Kpodo KR, Duttlinger AW, Johnson JS. Pen location affects thermoregulation and feed efficiency in swine during late summer. J Animal Sci. 2017;95(suppl 4): 245.