Avoid summertime blues when raising pigs

Avoid summertime blues when raising pigs

*Dr. Gil Patterson is with the Swine Vet Center in St. Peter, Minn.

AS with every season, summer presents its own unique set of challenges when it comes to raising pigs. Not only is it necessary to consider strategies for the anticipated drop in daily gain caused by hot weather, but careful attention to climate control also becomes especially important to avoid losing pigs due to overheating.

In addition to slowed growth, summer heat also exaggerates a few common pathogens that can cause sudden mortality in pigs, particularly erysipelas and ileitis, which both have a propensity to worsen during the summer and often can be fast moving.

With hog prices this summer the highest they've ever been, failure to adequately prepare for these challenges can result in huge losses in opportunity.

The purpose of this article will be to describe the most common environmental and health challenges brought on by the hot weather and discuss common strategies to alleviate them.


Barn environment

Keeping pigs cool during the heat of summer must be a priority in order to minimize both performance loss and mortality. The first thing pigs will do when they become overheated is reduce their feed intake.

Some producers will attempt to address this reduction in intake by increasing the nutrient density of the diet. This is not a cure-all strategy, so the focus should also be on maintaining an environment for the pig that is as cool as possible.

Spend the time to take basic precautions against excess heat by assuring that maintenance of the barn's ventilation system is up to date. Repair broken or dirty fans and louvers, blocked attic inlets, air leaks and damaged air inlets. Tighten bandwidths between fan stages to allow faster movement into full ventilation for finishing pigs. Make sure tunnel fans are working and that curtains can open completely.

Emergency backup generators and curtain drops should be tested once per month at a minimum, and weekly inspection is recommended. Documentation of emergency backup equipment inspection should be kept in a log book with dates and signatures at the generator.

Override thermostats should be connected and functional. They should be set for 3-5°F above the temperature at which the fan stage they are connected to operates. Stir fans provide additional air movement in curtain-sided barns and should be set to operate at approximately 12-15°F above the set point. They should be oriented so they produce a strong linear movement of air directly over the pigs.

Sprinklers or drippers provide additional cooling to the pig but are commonly mismanaged. They are most effective when directly wetting the pig's skin, followed by a period of evaporative drying. Maximum cooling occurs during the evaporation phase, not during the wetting phase.

A general recommendation is to begin wetting growing and finishing pigs when the air temperature in the barn is 80°F. Sprinklers should wet no more than 60% of the pen area in two minutes or less of "ON" time. The sprinklers should then remain "OFF" for 15-30 minutes. Observe to see if the concrete slats are drying in between wetting phases. If this is the case, reduce the sprinkler off time so that evaporative cooling is occurring during the entire "OFF" period.

It is also important to adjust nozzles for large water droplets to minimize water evaporation into the air before it reaches the pigs.



Transportation of pigs of all sizes during the summer is particularly challenging and all too often results in unnecessary losses. On hot days (above 70°F), adjust stocking densities accordingly.

The "ideal" transport space per pig is variable and depends on many factors, including ambient temperature, pig size and trip length. However, as a general rule, as the temperature rises, stocking densities must decrease.

Refer to a current Transport Quality Assurance (TQA) manual for recommendations on pig space based on size (Table 1), but be prepared to provide additional space on days that are excessively hot (above 90°F). Pigs should be loaded and unloaded promptly from trailers to avoid excess heat buildup.

At the same time, personnel responsible for loading pigs must stay calm and patient when moving pigs to prevent undue stress and fatigue. Consider the provision of incentives for good performance.

Pay attention to current and predicted weather reports at both the farm of origin and destination, particularly when the destination may be several hours away, and use this information to determine the level of bedding in the trailer (Table 2). TQA provides detailed information regarding the extent of side paneling and vent openings based on ambient temperature.

In addition, drivers should be prepared to adjust their routes if significant delays are anticipated. If the temperature is above 80°F, spray pigs with water, if possible, before leaving to allow a chance for evaporative cooling. Always keep the trailer moving to provide airflow over the pigs, as idle time will result in a rapid increase in the temperature inside the trailer.


Infectious challenges

Summertime also brings its share of infectious challenges, and some common pathogens are known to manifest in the summer.

Erysipelas and lawsonia (the causative agent of ileitis) are two of these. Acute infections can cause sudden mortality of multiple pigs. Unfortunately, the onset and progression of each of these diseases is rapid, requiring quick recognition and treatment decisions.

Erysipelas in growing pigs is characterized by a rapid spike in lameness, anorexia, fever and mortality. Signs of septicemia are usually present, which include red or purple discolorations of the pig's extremities and enlargement of the liver and spleen. Oftentimes, classic "diamond-shaped" skin lesions can be observed. Diagnosis is confirmed by submitting samples from acutely affected pigs.

Response has often included a combination of vaccination and treatment of all pigs with an appropriate antibiotic. Control and prevention measures can include a booster vaccination at the sow herd of origin and have also commonly included an orally administered vaccine booster in the nursery.

Ileitis, in its acute form, is often characterized as a sudden onset of bloody stools and mortality. Pigs will often appear pale but will be in good body condition. This can help distinguish ileitis from stomach ulcers, where the pale pigs are usually weak and emaciated. Classic lesions are a thickened ileum that includes blood clots.

Treatment should include an antibiotic injection of all pigs in pens where clinical signs are observed, as well as any neighboring pens. Often, an entire barn must also be treated through the feed or water.

Appropriate diagnostics can confirm ileitis. The site should be thoroughly cleaned, disinfected and inspected before refilling. Don't forget to clean and disinfect all boots and equipment that may have come into contact with pigs.

Vaccination is the hallmark of preventing ileitis outbreaks; however, among unvaccinated pigs or pigs that have a questionable vaccination status, antibiotic treatment programs based on diagnostic information can be used to prevent the sudden onset of disease.



Summertime brings its share of challenges that can turn bad for a group of pigs within a short time frame. Hot weather cannot be controlled, but a well-managed barn environment can reduce its burden on growing pigs.

Transportation of pigs during the summer can be a risk, but common sense and practicing good TQA principles can go a long way.

Besides all of this, the swine industry also needs to be aware of infectious agents that are prone to show up more acutely in the summer. Erysipelas and ileitis are both treatable diseases, but both require a rapid therapeutic response.

Careful management and planning for these seasonal challenges will result in more pigs to sell at the time they are most valuable.


1. Transportation space recommendations

Average weight (lb.)

Sq. ft. per head


























2. Recommended truck setup procedures based on air temperatures (market pigs)

Est. air temperature, °F


Side slats


Heavy (6 bags)

90-95% closed


Heavy (4-6 bags)

75-90% closed


Heavy (4-6 bags)

50-75% closed


Medium (3-4 bags)

50-75% closed


Medium (3-4 bags)

25-50% closed


Medium (3-4 bags)

0% closed


Light (1-2 bags)

0% closed

*Bedding refers to 50 lb. bag of wood shavings recommended per trailer.

Source for Tables: Transportation Quality Assurance Handbook.


Volume:86 Issue:21

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