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Cull Sow Plan Can Lower Per-Pig-Weaned Cost

Swine Management Systems (SMS) defines genetics cost on a cash flow basis as the purchase of breeding animals, breeding animal development expenses, purchase of semen, purchase of artificial insemination supplies, payment of genetic royalties and sale of cull breeding stock.

The SMS financial database has an average genetic cost/weaned pig of $3.01. The top one-third averages $2.12/weaned pig and the bottom one-third averages $3.76/weaned pig.

A key driver in the genetic cost is cull breeding stock income, which averages $2.79/weaned pig, with the top one-third averaging $4.15/weaned pig and the bottom one-third averaging $1.91/weaned pig. On most farms, cull breeding stock income is not considered a key driver, but our data shows it can help lower the weaned pig breakeven by over $2.00/pig from the bottom one-third to the top one-third.

Wiechman Pig Company and SMS developed a training program for owners and employees on how to determine which cull females to market at weaning and which to feed to maximize their value and income. Cull sows are broken down by weight category and body condition. The weight range categories are: 300-450 lb., 450-500 lb., 500-550 lb., and 550 lb. and up. Body condition classifications are: Boner 1 – wet sow, clean, lean and without multiple abscesses or major defects; Bone 2 – very lean, emaciated, multiple abscesses or poor quality and no value or a downer sow.

Cull sow prices are posted daily by USDA Market News in a report called Daily Price Summary. Daily prices can be found at their web site:

Sow Weight Affects Value
The weight range that sows fall into can increase or decrease the income per sow. Feeding a sow to gain enough weight to go from the 300-450-lb. range to the 450-500-lb. range could increase her value by $6.00/cwt. or more. On a 460-lb sow, the increased value would be at least $27.

Calculate feed and housing costs, factor in the potential death loss to calculate whether adding the extra weight on cull sows provides a good return on your investment. Weaned sows are very efficient at putting on extra weight the first 2-3 weeks after weaning, which keeps the cost per pound of gain very low.

At weaning, it is best to sort sows by weight and body classification. If you don’t have a scale, there are two options for estimating weight using a tape measure – measuring the sow’s heart girth (behind the shoulders) or measuring rear flank-to-flank. With the flank-to-flank measurement, sows measuring less than 35.5 in. weigh less than 325 lb.; sows from 35.6 to 38 in. weigh 325 to 400 lb.; sows 38.1 to 41. in. weigh 400 to 475 lb.; sows 41.1 to 44.0 in. weigh 475 to 550 lb.; and sows measuring 44.1 in. or more weigh 550 lb. or more. This information was taken from the 2004 Kansas State University Swine Day.

SOPs for Cull Sows
If you want to increase your cull sow income and possibly reduce your cost to raise a weaned pig by up to $2.00, you’ll need to develop a set of standard operating procedures (SOP’s) for your farm. Here are a few ideas:

• Have an acceptable place to house sows for 20-60 days.

• Develop a convenient way to check weight and backfat of cull sows so you know which sows to hold and feed and to guide how long to feed them.

• Develop written procedures for selecting the sows to retain for additional feeding based on health, mobility and their ability to compete in group.

• Establish written procedures for euthanizing downer and crippled sows.

• Select a market outlet for sows that will pay based on weight and body condition vs. a fixed price.

• Set a goal to market sows at more than 85% of the quoted USDA National Slaughter Sows Summary.

• Monitor feed cost to determine how long to feed cull sows to an optimum weight. Adjust as feed prices increase or cull sow value declines.

• Review sow marketing program and make adjustments to improve the quality and value of cull sows. Everyone is looking for ways to reduce costs and improve profits. Creating an organized plan to market cull sows may be an opportunity to lower per-weaned-pig cost that you haven’t considered.

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