Parity Links to Litter Size

As we enter our second year of writing these benchmarking articles, we invite you to suggest topics you’d like to see us address. The focus for this article came from a telephone conversation we had last week with one of our clients.

As we enter our second year of writing these benchmarking articles, we invite you to suggest topics you’d like to see us address. The focus for this article came from a telephone conversation we had last week with one of our clients.

The two charts (attached) are very cluttered, but they reinforce one of the problems encountered when analyzing data. Averages are nice to look at, but it is the variation that challenges the day-to -day management of a farm.

At Swine Management Services (SMS), every farm is treated as an individual and all the farm’s targets and standard operating procedures are set individually. The farms may have been built using the same blueprints, but there is always variation in how people manage the farm, the health of the herd, current parity structure, etc.

Chart 1 shows the percent of females farrowed by parity for a 52-week period. The 30 farms selected for this analysis have been in operation for over three years and have a mature parity structure. The black line is the average of the 30 farms and it shows a normal parity distribution.

In Table 1 (attached), the average parity for the most recent 52 weeks that data was available was a 2.71. The top 10% of farms had a parity average of 2.72 litters. When broken down by parity, excluding P0 females (gilts), the parity structure was: Parity 1 (P1), 20.8%; P2, 17.8%; P3, 16.0%; P4, 13.9%; P5, 11.9%; P6, 9.3%; and P7+, 10.3%.

When we have asked experts, such as Extension personnel, geneticists and genetics company representatives, what the ideal parity structure should be, we get a lot of different answers. If you want to know the ideal parity structure for your farm, talk with your genetic supplier.

All of the colored lines in Charts 1 and 2 represent individual farms and show the large parity variation between farms. The percent P1 females farrowed range from 16.0% to 25.3%. Some of the variation in P1 females seen this past year was driven by two factors – cull sow price and the need for cash flow. During the first part of the year, when cull sow prices were over $50/cwt., it made economic sense to cull “problem” sows and replace them with new gilts. In some cases, it even put cash in your pocket. After mid-year, when culling levels increased, sow and market hog values dropped, and cash flow became an issue, sow replacement rates dropped.

Chart 2 shows the average total born/female farrowed, by parity, for a 52-week period. Again, the black line shows the average for the 30 farms, which shows a normal progression of more total born/ female farrowed from P1 to P3, then a gradual decrease from P4 to P7+.

The average total born/female farrowed for all 30 farms was 12.56 pigs, which is 0.18 pigs/litter lower than the “all farms” average of 12.74 total pigs born/litter shown in Table 1.

The variation in P1 females is 10.50 to 13.69 total pigs born. Looking at the individual farms in the SMS database, the top farm is at 13.91 total born for all parities – starting at 13.69 total pigs born for P1 females and peaking at 14.26 total pigs born for P3 females. The farm that peaks out the highest at 14.61 total pigs born for P4 females starts out with P1 females farrowing 12.64 total pigs born. Four farms have fewer pigs for P2 than P1 females, and five farms have no increase from P1 to P2. These nine farms combined averaged 12.36 total born/female farrowed or 0.20 pigs fewer than the average of 12.56.

The top five farms average 13.63 total born for all parities compared to the all-farm average of 12.56, and an average of 13.15 total born for P1 females compared to 12.19 total born for all farms.

In looking at some of the farms at the bottom of the chart, there was one farm with an average born of 10.98 pigs and variation from P1 to P6 of 10.90 to 11.00 pigs, with a drop to 10.50 pigs for P7+ females. Another farm at the bottom starts with 10.50 pigs born at P1 and increases to 11.50 pigs born at P6 and declines to 11.13 pigs born for P7+. There is another farm that started with P1 females at 12.40 pigs total born and then showed a decline by successive parities: P2, 12.20; P3, 12.20; P4, 11.30; P5, 10.90; P6, 10.90; and P7+ increasing to11.20 pigs/litter.

When we look at data from farms with abnormal parity performance, the things we focus on are:

• Genetic potential of the females;
• Gilt development (number of skip heats, age, weight at breeding, etc.);
• Feeding program in lactation, especially for P1 females;
• Criteria used for culling females;
• Breakdown of female death loss, and
• Flow of 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