The higher your breeding herd's farrowing rate, the higher your profits. But faulty heat detection can cut into your farrowing rate and rob you of profits.

Improving farrowing rate by 5 percent can reduce nonproductive-sow days or let you generate the same productivity with fewer sows. It also could help you eliminate wrongful culling of sows for reproductive reasons that don't really exist.

"Improving heat detection industry wide could have a major effect on the industry's bottomline," says Wayne Singleton, Purdue University animal scientist.

Suppose a 2,500-sow farm breeds 150 sows or gilts a week, in order to farrow 110 litters weekly. Increasing the farrowing rate from 75 percent to 80 percent would allow the herd manager to reduce breedings from 150 to 137, which would help cut replacement gilt costs, says Ken Stalder, University of Tennessee swine specialist.

If a sow or gilt is not bred successfully, it takes 21 days before she's bred again. So, if you take the additional 13 sows that are bred successfully in the example and multiply that by the additional 21 days, an improvement of 5 percent in farrowing rate could prevent 273 nonproductive-sow days per month, notes Stalder. That adds up to 3,276 nonproductive-sow days a year, which would result in a savings of between $3,500 and $7,000 annually, depending on how nonproductive-sow days are valued.

"If your farrowing rate increases, your cost per mating decreases," says Billy Flowers, North Carolina State University swine reproductive specialist. "If you have accurate heat detection, most of your sows will get bred the first time around, saving you 21 or 42 days."

As another example of the value of raising your farrowing rate by 5 percent, if you bred 100 sows a week an additional 5 sows would farrow the first time around. If you have 10 pigs per litter, that could mean as much as an extra 50 pigs per week.

In addition to reducing nonproductive-sow days, there are other potential advantages to improving heat detection. Though there is little research on the topic, improved heat detection may improve sow longevity by reducing the number of animals culled for reproductive problems, when the real problem is faulty heat detection.

Taking steps to improve your farrowing rate to capture extra value depends on your current breeding program. Flowers says if you aren't using a heat-check boar to identify sows ready for breeding that should be your first step. If you are already using a heat-check boar you may want to expose the boar to fewer sows at a time.

Each boar is different in his ability to stay focused, but Singleton suggests limiting the heat-check boar's workload to 25 to 50 sows per session as a general rule, because the boar loses interest after that. Stalder says that the number of heat-check boars you need is dependent on your facilities as well as the individual boar. He also says that boars will vary from day to day, and should be rested when they are tired, which will be apparent.

Another way to improve this process, is to use a more vocal boar that is obviously interested in the sows or gilts. Stalder says the heat-check boar just needs to be sexually mature, but there is no maximum age as long as the boar is easy to handle and sufficiently active to stimulate the females. An effective heat-check boar will exhibit strong phero-mones and show strong reactions to the females by doing things like frothing at the mouth.

"How you expose sows and gilts to boars depends greatly on your operation," says Stalder. "I like putting the boar in a pen with the females, but obviously that won't work if you use crates."

If you use sow crates, Stalder suggests walking the boar in front of the sows and giving each sow several minutes of face time with the boar. Gilts should begin being exposed to boars at about 5.5 to seven months of age, provided they weight at least 250 pounds and have reached puberty. You should expose sows to boars four days after weaning the last litter and continue exposure until most of the group is in heat.

For larger herds where sows are checked for heat in crates, Singleton says consider using robotic boar controllers. This saves labor and insures face-to-face boar/sow exposure. Training boars to a harness is a common method of controlling boar movements, says Singleton.

Of course, your heat detection abilities are only as good as the employees that are checking for heat.

"It starts with good people, who know what they're doing, I can't emphasize that enough," says Stalder. "It takes constant observation to make sure the right things are being done all the time, not just when the consultant is there."

Stalder suggests there are three things that make a good stockman:

  • Keen observation skills.
  • Knowledge of what to do once something is observed.
  • A positive, can-do attitude.

He recommends sending employees to artificial insemination schools put on by the National Pork Board, university Extension programs or other sources. Obviously this is wise for new employees, but even existing employees can benefit from a refresher.

Flowers cites three critical steps to improve heat detection:

1. Make sure the people checking for heat know and understand the signs of heat for a gilt and a sow. Gilts can present more of a challenge because the signs can be more subtle.
2. Take a hard look at your operation and the interaction between boars and sows and people to try and discover your own problems.
3. Get a more objective opinion about your breeding program. Consult a fellow pork producer, an Extension swine specialist, veterinarian or other related consultant.

One positive about refining your heat detection skills is that you can make improvements with a relatively low investment.

"Most improvements may involve a change of how you do things, rather than new equipment or technology, so the opportunity cost is usually pretty small," says Flowers.

"There's probably not any major investments to make, unless you haven't brought in replacement heat-check boars often enough," says Singleton. He suggests replacing heat-check boars at least quarterly. He also suggests allowing time for new heat-check boars to acclimate, mature and become trained. Not all boars will be good heat checkers, so some selection may be needed.

Stalder also points to PG 600, which stimulates the sow to come into heat. PG 600 costs $4.75 per sow, and may help improve your overall heat detection successes.

In warmer climates and warmer months, sows may have trouble coming into heat. They could be good candidates for PG 600.

"Products like PG 600 have been effective for problem sows and in unfavorable situations," says Stalder.

Flowers says products like PG 600 may help some farms, while for others it has little
effect. Some gilts and sows are probably given treatments when they aren't in a physiological situation to respond, so how the product is used becomes important, as well.

With issues like reproductive management becoming more important, a second look at all the little things involved is required. Improving heat detection may be one of these small steps that could have big rewards.

Making the Grade on Farrowing Rates
How do you determine if you need to improve your farrowing rate? Billy Flowers, North Carolina State University, has a rule of thumb – he issues a report card, similar to receiving grades in school.

"I tell people the higher the better, but if they're below 80 percent there's room for improvement," says Flowers. He equates an 85 percent to 90 percent farrowing rate with receiving a grade of A. An 80 percent farrowing rate would fall in the B range. Anything lower could use some work.

Ken Stalder, University of Tennessee, points out that it's probably easier to move from a 75 percent farrowing rate to one at 80 percent, than to move from an 80 percent rate up to 85 percent. Flowers agrees, adding that if your farrowing rate is at 80 percent, heat detection probably isn't one of your major problems. Poor heat detection abilities usually drop farrowing rates well below 80 percent.

Sources of More Information
Here are three resources that you can use to learn more about heat detection.

  • Reproductive Management of Pigs: Guides and Problem Solving Sus Multimedia Publications, P.O. Box 5332, Fargo, ND 58105-5332. Authors: Paul Hughes, Billy Flowers, Roy Kirkwood, Don Levis, Jim Tilton, Niroline Soede and Phil Thacker.
  • Recognizing and Treating Pig Infertility by Mike Muirhead and Tom Alexander covers such topics as anatomy and terminology, drug usage, monitoring breeding performance, genital diseases and management of infertility. The cost for U.S. producers is $36 per copy (not including postage). For more information about the book or to order, check out the Web site at
  • The Swine AI Book, Second Edition. This book is available through most equipment companies and other outlets that sell livestock equipment, or you can visit