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Heat Detection, AI Skills Impact Farrowing Rate

For this week’s column, we will focus on 22 farms where the artificial insemination (AI) staff records key reproductive performance indicators. This information was then run through two of Swine Management Services’ (SMS) specialized reports – the In-Depth Breeding Analysis Report and the Breeding Technician Report.

These reports look at farrowing rate by AI technician, semen batch code, sow parity, number of matings, days-to-first estrus, days-to-estrus return, day of the week bred, time of the day bred, lactation length, etc. Data was run on the most current 52 weeks of breeding results to ensure records were updated and all bred females had farrowed. Farms in the database vary by size, genetic lines and geographical locations.

We will focus on farrowing rate by AI technician and wean-to-first-service day by AI technician. We narrowed our analysis to 30 AI technicians who had over 500 services during the time period, which represented a total of 98,792 services.

We feel wean-to-first-service interval influences farrowing rate and subsequent litter size. The dataset (22 farms) had an overall average wean-to-first-service interval of 6.3 days, with a parity breakdown for average wean-to-first-service interval as follows: Parity 1 = 8.3 days; Parity 2 = 6.1 days; Parity 3 = 6.2 days; Parity 4 = 5.8 days; Parity 5 = 5.7 days; Parity 6 = 5.5 days; and, Parity 7 or higher = 4.7 days.

We were surprised to see Parity 1 females averaging only 8.3 days to cycle. This tells us that farms are doing a better job of developing gilts, breeding them at heavier weights, and making sure they are eating well in their first lactation.

Table 1 shows wean-to-first-service interval by day bred – from Day 1 to 24. The farrowing rate for all farms (30 technicians) was 85.2%.

As the table shows, only 7.4% of the sows were bred within three days after weaning and the farrowing rates were 67.9% for those bred on Day 1, 77.2% for Day 2, and 81.8% for Day 3. Clearly, the technicians who do not start heat checking until Day 4 or 5 after weaning will miss the early cyclers, which means those sows would likely be bred 18-24 days after weaning, on their second heat cycle.

The sows bred on Days 1-3 are probably nurse sows, sows that have been lactating longer, or sows that were split-weaned with more than two pigs removed early. The data shows these sows are in a fertile heat with very good farrowing rates if bred.

We recommend that boar exposure and heat checking begin the first day after weaning and any sow found in heat should be bred. Our data shows the percentage of sows cycling Day 1-3 has increased as weaning age increases and as more farms do a better job of feeding sows in lactation.

In this comparison, females bred on Days 4-6 accounted for 81% of the sows weaned. Farrowing rate for sows bred on Day 4 was 87.4%, Day 5 was 86.8%, and Day 6 was 81.5%. The data also shows that sows bred Days 7-11 after weaning have lower farrowing rates, with some improvement for sows bred on Days 12 and 13. There is a nice increase in farrowing rate for sows bred on Days 19 and 20 (85.2 and 85.3%, respectively), but as we noted above, some of those sows are likely on their second heat, having cycled on Days 1-3, but were not bred.

We have reviewed other data where first-parity females were skipped (not bred) on their first cycle after weaning and bred on their second cycle. These sows showed a small increase in total pigs born over Parity 1 females that were bred on their first heat. To cover the cost of housing and feeding a sow an extra 18-21 days, you will need to gain at least 1 pig/litter.

Also in Table 1, we broke down the data of the 30 technicians into the Top 15 and Bottom 15 percentile. As you can see, the farrowing rate average for the Top 15% averaged 88.3% farrowing rate, while the Bottom 15% averaged 82.1% for the 52-weeks breeding period.

Technician Abilities Vary
Chart 1 shows the farrowing rate for each technician for the 24-day, post-weaning period. Although the chart is very busy, it shows the large amount of variation between AI technicians, as well as the variation for each technician from day to day. The black line in Chart 1 corresponds with the second column (overall farrowing rate) in Table 1. Clearly, on any given breeding day, there is a wide variation in farrowing rate by technician.

If you look at females bred on Day 4, the average farrowing rate was 87.6% (range 76.2 to 91.3%), while sows bred on Day 9 after weaning had an average farrowing rate of 70.0% (range 33.3 to 100%). The chart shows that most technicians do a much better job of breeding sows on Days 4-6 after weaning.

Charts 2 and 3 show technicians ranked in Top 15% and Bottom 15% for farrowing rate during the 52-week period. In both charts, top farrowing rates were sows bred on Days 4-6 after weaning and the bottom technicians show another peak for females bred on Days 18-20. You’ll also note the drop in farrowing rate when sows are bred Days 7-9.

The biggest issue is 5-6% difference in farrowing rate between the Top 15% and Bottom 15% of technicians. That is probably a difference of 1.6 to 2.0 pigs weaned/sow/year.

With 80.7% of weaned sows bred by Day 6 having the highest farrowing rate, the challenge is the other 18 days that breeding takes place. It is important to remember that the technician represents one-third of the inputs for breeding success, the other two thirds being the female and the semen.

It is a good idea to review breeding procedures periodically and to try some new ideas, such as changing how sows are fed in lactation. Some producers have found full-feeding sows after weaning improves the number that cycle within 3-6 days. Consider heat checking late weaners twice per day to help time the insemination closer to ovulation. Or, if only heat checking once daily, consider breeding these sows in the morning and afternoon – at least six hours apart – to lower the number of sows being bred only once.

What is an acceptable farrowing rate? The SMS Benchmarking database (755 sow farms) has an overall average of 84.6%. The Top 10% of farms average 88.2%; 82 sow farms have a farrowing rate over 90%.

We feel it is important to keep a record of the technicians doing the inseminations, the semen batch number and, if possible, the time of day that females are bred. Then, a detailed analysis will help identify where the problems are so that changes can be made in personnel, training and updating standard operating procedures.

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