By JoAnn Alumbaugh

Improving farrowing rates in a pork operation can have significant economic value. According to Swine Management Services, a farrowing rate improvement of 4% will increase pigs/sow/year by approximately 1.35 pigs and reduce the breakeven by approximately $1.75/weaned pig. That 4% would also allow for a reduction in sow inventory by approximately 5%, while producing the same number of pigs and reducing breakeven by approximately $0.25/ weaned pig.

North Carolina State University data have shown a high correlation between farrowing rate and live pigs born per bred sow per year, says Don Levis, professor emeritus at the University of Nebraska. 

“Their data show that for each 10% increase in farrowing rate of bred sows, there is a corresponding increase of 2.63 live pigs born per sow per year. In light of these data, pork producers should strive to maximize farrowing rate,” he said in a presentation. “This can be done by providing good management during pre-breeding, breeding, and gestation phases.” 

Farrowing rate is one of the key drivers of pig farm performance, says Brad Schimmer, technical services specialist for PIC. He notes that five areas are pivotal to achieving good farrowing rates: heat detection, the insemination process, semen management, feed management/body condition, and choosing the right females. 

1 Pay attention to heat detection

Heat detection starts with understanding how the heat cycle works, he explains. The chart below indicates the desired window for breeding to achieve a 95% target conception rate.

“The farrowing rate will be as good as the capacity of the farm to find females in heat at the right time,” Schimmer says. “Missing the heat by just 24 hours can compromise performance.”

He suggests producers identify and mark females that start to show early signs of heat (swelling vulvas, mucous discharge, or ears going up but not locking up when mounted). Let gilts get used to a boar first, then proceed to heat detection, he says.

It’s important to put heavy pressure on a female’s back, to mimic a heavy boar, and “if you’re in doubt, sit on the sow: If she doesn’t move and is silent, it’s the right time to breed her; if she continues to move or make noise, it’s better to wait,” he adds.

2 Take your time in the insemination process

Breeding is a little bit like an art, Schimmer says. There can be a general process, but some sows or gilts take a longer or shorter time in the semen dose uptake when utilizing conventional artificial insemination. A sign that the process is too quick is the occurrence of semen back flow. Slow down the process by elevating the end of the catheter. 

There isn’t an “exact” amount of time required for the breeding process, because each female will respond differently and employees have different levels of expertise. 

“Gilts make up a special group and must be treated as such,” Schimmer says, adding that a 3-minute average is likely not long enough. Also, if the employee sees semen back-flow, it indicates something is wrong.

3 Remember semen quality

Keep semen alive and strong, asserts Schimmer, and remember that semen age is relevant. “Over-ordering may force you to use older semen,” he says. “Semen dose can limit total born numbers by 0.3 pigs and impact farrowing rate by 2% per day of storage, so it’s better to receive semen more frequently – for instance, three times a week.” 

Semen temperature is important, too. “Semen must be stored between 61 degrees and 64 degrees,” Schimmer recommends. “Even a 3.6-degree fluctuation can reduce shelf life up to one day!”

Unpack semen doses before putting them in the refrigerator and store doses loosely and horizontally to allow for air circulation. Check temperatures in the storage unit daily, and when semen is removed for use, put it in an insulated container with gel packs to maintain temperature. Post-cervical artificial insemination (PCAI) low sperm cell doses are more sensitive to temperature fluctuations and need special attention, Schimmer adds.

“It’s a one-way road,” he says. In other words, any semen not used in the breeding barn should not be put back in the refrigerator for future use. Breeding staff should know how many sows or gilts will be serviced to avoid taking too many doses to the breeding barn.

4 Focus on feed management and body condition

Monitor sow body condition on a weekly basis to keep from breeding females that are either too fat or too thin, Schimmer notes. Set reminders so this is a regular occurrence, and set feed boxes accordingly. He suggests producers evaluate groups at breeding, and at 4 weeks, 8 weeks, and 12 weeks of gestation.

“Consider using a caliper to make the body condition evaluation objective to tailor your feeding program,” he says.

Wean-to-service interval and breed-back times are both good indicators of body condition management and proper lactation feeding.

“When feeding is done right, more sows can be bred on days 4 and 5 post-weaning,” he says.

5 Choose the right females

Culling should be used as a management tool, and producers should make a regular habit of eliminating the bottom 10% of the females in their herds. Culling allows producers to limit the number of older parity females on the farm, while also removing younger parity sows who aren’t performing well or are having an issue that won’t allow them to deliver another litter.

“Achieving the right breeding target will always be a priority, so work on optimizing gilt entry and reducing involuntary culling,” Schimmer says. Lameness is often the primary reason for involuntary culling.

To minimize this factor:

•    Select gilts with good feet and leg structure

•    Control body condition

•    Consider using copper sulfate if you see major lameness issues coming from cracked hooves or sole lesions.

Fill pens with sows of similar size and parity if group housing is used. Also, ensure the right quantity and quality of gilts are entering the farm, focus on puberty induction, and treat the gilt-development unit as the future of the farm by making it a priority, Schimmer says.

Details matter when it comes to improving farrowing rates. “Each action may have a small impact alone, but can have a huge collective impact. Understanding the drivers of farrowing rate and implementing tactics to improve it will bring better performance,” Schimmer says.