Pigs often grow slower during the hot summer months than at other times of the year. This is especially true during July and August in the central part of Washington. As a result, pigs are delayed in reaching market weight which disrupts pig flow, feed efficiency and profitability in commercial units. Show pigs fail to make minimum weights for local and regional fairs and youth are very disappointed. Also, pigs are uncomfortable and their well-being may be compromised. Most of these consequences are preventable with proper management.
How hot is too hot for pigs from 50 to 260 pounds? Managers, including youth, should be on the alert at temperatures above 75 degrees. The Danger Zone is any time temperatures approach 100 degrees or above. Remember, pigs kept outside without adequate shade are going to be in the Danger Zone when the thermometer on your porch reads 80-85 degrees. Keeping pigs at temperatures in the Danger Zone represents inhumane treatment.
Pigs are more sensitive to heat and humidity than humans and some other animals like the horse. Don’t forget, pigs do not sweat! They cool themselves primarily by heat loss via the lungs, skin and urine. Therefore, providing cooler air for them to breathe, increasing consumption of cool water which will increase urinary water loss and providing water misting or dripping on their skin will all increase heat loss from their bodies and keep them cooler even when the thermometer rises above 80 degrees. Mud wallows partially accomplish the same purpose, but are not very sanitary and can spread diseases and parasites.
The key factors to monitor during the summer that may decrease rate of gain and feed efficiency and compromise animal well-being are 1) feed intake, 2) water consumption, 3) cooling and ventilation, 4) pig handling, and 5) space allowances.
Feed consumption is usually the first thing affected by high environmental temperatures. Finishing pigs will usually eat less when temperatures in their pens, houses or shelters exceed 80 degrees for more than 4-6 hours unless they are cooled in some way. A 5-7 percent decrease in daily feed intake is very common for commercial pigs and this will result in at least a 10-20 percent slower rate of gain. Growth rate decreases more than feed intake because a larger proportion of the feed consumed must be used for maintenance, leaving even less for weight gain. For example, a 200 lb pig should be consuming 6.5 lbs feed per day and gaining 1.8 lbs per day under normal conditions. Just moderate heat stress might decrease feed intake by 0.40 lbs per day (6%) and rate of gain by 0.30 lbs per day (17%). Please note that feed efficiency will also drop from 3.6 lbs of feed per lb of gain (6.5/1.8) to 4.1 (6.1/1.5), or about 14 percent. This is very costly to commercial producers. For youth with project pigs, a decrease in rate of gain of just 0.3 lbs per day over two months will impact weigh-in by 18 lbs at show time. However, this could easily be 30-35 lbs or more under conditions often seen for pigs kept outdoors with minimum shade, especially in the Columbia Basin. Remember, you cannot make up for this slower gain once it has happened.
Pigs must have an adequate supply of clean, cool water continuously. Pigs that don’t drink enough water almost always eat less feed and grow slower. A finisher pig needs 5 gallons of water per day, more if it’s very hot. A change in ambient temperature from 60°F to 90°F increases water needs by 25-50%. Never try to provide project pigs water in pens or troughs even if you do so 5- 6 times per day. They simply won’t drink enough. Either nipple or cup waterers are acceptable but never locate them in direct sunlight. Nipples become so hot that pigs are reluctant to use them during late morning and all afternoon. Make sure that the flow rate of nipples is at least 3-4 cups per minute. If you don’t know,
check it! If you use a hose or pipe to bring water from a faucet to your pigs, do not leave it on the top of the ground exposed to the sun. The water gets so hot during the day that the pigs won’t drink. Cover the hose with soil or an insulating material that won’t blow away.
Make sure that cooling and ventilation systems are operating correctly. Check fans, air inlets, cool cell pads and water misting or drip systems. Clean dirty fan blades and replace any worn fan belts. Pigs kept outside must have shade throughout the day. Use a water mist located in the shade during the hottest times of the day.
Handle pigs during the cooler parts of the day. Move them in small groups to keep them calm, about 5 is best. Use panels or hurdles, never an electric prod. Don’t excite them with loud noises or yelling. Watch for signs for heat stress including rapid breathing with an open mouth, squealing, blotchy skin and muscle tremors.
Space allowances are more critical during summer. Crowded pigs will fight more, eat less and grow slower. Growing pigs need about 6 square feet per animal up to 150 pounds and 8 square feet after that.