As we continue to analyze the effect of weaning age on sow herd performance, we have three more areas for discussion and review: total born/mated female, born live/mated female and pigs weaned/mated female.

As we review the research literature, the effect of adding one day to weaning age on total pigs born/litter varies. The range is 0.08 to 0.14 pigs/day added. So if you increase weaning age by four days, you could expect to increase total pigs born by 0.32 to 0.56 pigs/litter.

Table 1 features data from the 686 farms representing 1,211,000 females in our data set. We have summarized the data in Table 1 in three areas – total pigs born, pigs born alive, and pigs weaned/litter in the following categories: Top 10%, Top 25%, Top 50%, All Farms, Bottom 50%, and Bottom 25%, based on pigs weaned/mated female/year. All farms in this data are weaning, on average, 20+ pigs/mated female/year.

“Per Litter” Effects
Charts 1-15 show the impact of weaning age on “per litter” production. Weaning ages are: less than 18 days of age (70 farms), 18 days of age (126 farms), 19 days of age (172 farms), 20 days of age (163 farms), 21 days of age (72 farms), 22-23 days of age (57 farms) and 24+ days of age (26 farms). Staff at several farms pointed out that at 24+ days, the data becomes distorted by the large number of nurse sows being used.

Chart 1 shows total born/female vs. weaning age. Farms in the Top 10% start at a weaning average of 12.91 pigs/litter (less than 18 days of age), increases to 14.32 pigs/litter at 20 days of age, then drops back to 13.54 pigs/litter at 22-23 days of age. Average litter size at 24+ days of age is 14.88 pigs.

For all farms, with average weaning age at less than 18 days of age, litter size averages 12.81 pigs. At 20 days of age, litter size climbs slightly to 13.07 pigs, then declines to 12.61 pigs at 22-23 days of age. At 24+ days of age, litter size weaned takes a big jump to 13.61 pigs/litter. It is important to know that only 26 farms weaned at 24+ days of age and only four of them ranked in the Top 10%.

Charts 2 through 5 present total born/female trend lines (12 quarters of most recent data) for four weaning ages: 24+ days, 21 days, 19 days and less than 18 days of age. Farms with a weaning age of 24+ days of age improved from 12.7 to 13.7 pigs/litter over the 12 quarters; farms weaning at 21 days of age improved from 12.0 to 12.7 pigs per litter for the period, while farms weaning at 19 days of age climbed from 12.5 to 13.2 pigs weaned/litter. Farms weaning at less than 18 days of age improved just 0.6 pigs/litter, starting at 12.2 and ending at 12.8 pigs/litter, which should likely be attributed to genetic and management improvement, not weaning age.

Chart 6 features liveborn pigs/mated female vs. weaning age. Like total born/mated female, the number of live pigs farrowed increases as weaning age goes up to 20 days, then drops at 21-23 days of age at weaning, and recovers at 24+ days of age. Remember there are only 26 farms in that data set.

Charts 7 through 10 are also broken down by the four weaning age groups used in Charts 2-5, again looking at the last 12 quarters. For that period, pigs weaned at 24+ days improved 0.50 pigs/litter, at 21 days of age grew by 0.60 pigs/litter, at19 days of aged increased by 0.50 pig/litter, and at less than 18 days of age improved 0.50 pigs/litter. Once again, gains in pigs born live/litter are likely affected by genetic improvement and management improvement rather than weaning age.

Chart 11 looks at weaned pigs/mated female vs. weaning age. For All Farms, average pigs/litter when weaned at different ages were: 10.96 at 24+ days of age, 10.02 at 22-23 days of age, 10.27 at 21 days of age, 10.16 at 20 days of age, 10.26 at 19 days of age, 10.10 at 18 days of age, and 10.13 pigs at less than 18 days of age.

When looking at the Top 10%, the range in weaned pigs/mated female went from 10.88 at less than 18 days of age to 11.36 pigs when weaned at 22-23 days of age – a gain of 0.48 pigs/litter. The data shows no advantage in increasing weaning age to improve pigs weaned/mated female.

In Charts 12-15, the 12-quarter trend for pigs weaned/mated female farrowed is shown. Pigs weaned at 24+ days of age grew from 10.5 to 10.9 pigs/litter in three years. Similarly, weaning age at 21 days improved 9.6 to 10 pigs weaned, at 19 days improved from 10.0 to 10.3 pigs, and at less than 18 days of age, grew from 9.8 to 10.0 pigs.

In summary, weaning age may have limited affect on total born, liveborn and number weaned/mated female. The trend is for all numbers to peak at a weaning age of about 20 days of age. There was a large improvement when weaning age went over 24+ days, which, again, we are not sure of because of the small number of farms that averages are based on and the fact that more nurse sows were being used.

One of the top-producing farms in the over 24-day age group noted they never wean an original litter over 24 days of age, but some nurse sows will wean as high as five litters.

When we looked at the trends for the last three years, genetic improvement is probably driving the increase of less than one pig per litter. If you need to increase weaning age, there are several factors to consider, such as “skip” heats on gilts, better boar exposure for gilts before breeding, increasing daily feed intake during lactation and from weaning to breeding.

Key Performance Indicators
Tables 2 and 3 (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