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More Gilt Management Tips to Improve Breeding Herd Performance

Last week, we listed several management areas that have an impact on “total pigs born.” (To review, click here).

In addition to the number of recorded heat cycles before breeding and the gilt’s exposure to gestation stalls before breeding, there are additional management factors that affect gilt performance. Following are a few additional considerations:

Level and length of lighting in the gilt development area. Studies have documented the impact of light intensity and duration on gilt development and cycling, especially in the fall as daylight decreases. Light does affect onset of puberty and length of breeding periods. We suggest having a timer in the gilt development area that allows for a minimum of 16 hours of light per day, with an intensity of 50 lux, roughly 100 watts of light for every 100 sq. ft. of floor space. Gilts do need a sleep period, so the lights need to be off during the night.

Weight at breeding. A gilt’s weight at breeding is critical to her longevity. There is general agreement that the ideal weight range is 300-350 lb. If too light, gilts will be challenged at first parity and a high percentage will experience a second parity dip caused by poor body condition, inability to breed back and, subsequently, small litter size. If the gilts are too heavy, it may have an adverse effect on first parity lactation and these gilts are often culled because they get too big for the farrowing crates and gestation stalls. If a scale is not available to weigh gilts in the breeding area, a flank-to-flank measurement can offer guidance. If the tape measures over 34 in., her weight is probably over 300 lb.

Backfat level at breeding. Backfat depth measurements are not getting a lot of attention these days, but some research shows gilts bred with less than 0.50 in. of backfat will have smaller litters and poorer lifetime performance. Backfat depth can be measured with a backfat probe or an ultrasound machine. Target a minimum of 0.50 to 0.60 in. of backfat at breeding.

Age at breeding. Most breeding herds do not keep track of the gilt ages, they don’t record it, or they have not adopted a recordkeeping system based on female inventory. If you do not track gilt age, be sure they weigh at least 300 lb. and have had at least one recorded heat cycle before breeding.

Age at first boar exposure. Boar exposure is often dependent on the gilt replacement flow and the number of heat cycles desired before breeding. When you start boar exposure, use mature boars with daily exposure. Place boars in the gilts pens for at least one minute/gilt in the pen. A pen of 20 gilts should then have at least 20 minutes of boar exposure.

Gilt housing environment. The environment in which gilts are raised has a lot of influence on estrus. Gilts should have 12-15 sq. ft. of space/gilt and a temperature range of 60 to 85oF. If too cold or too hot, gilts can be stressed which may cause them to stop cycling. Cool cells and drippers can help cool gilts during hot weather.

Genetic potential.The Swine Management Services database has many different genetic lines represented. Most of those lines have the genetic potential to produce 25+ pigs/sow/year when managed correctly.

To summarize, if your goal is to increase total pigs born, you must develop farm-specific standard operation procedures (SOP’s) for handling, feeding and breeding replacement gilts.

Key Performance Indicators
Tables 1 and 2 (below) provide 52-week and 13-week rolling averages for key performance indicators (KPI) of breeding herd performance. These tables reflect the most current quarterly data available and are presented with each column. The KPI’s can be used as general guidelines to measure the productivity of your herd compared to the top 10% and top 25% of farms, the average performance for all farms, and the bottom 25% of farms in the SMS database.

If you have questions or comments about these columns, or if you have a specific performance measurement that you would like to see benchmarked in our database, please address them to: or

Click to view graphs.

Mark Rix and Ron Ketchem
Swine Management Services, LLC