What and when: Deeper look at wean-to-finish mortality

When receiving health challenged pigs, key to have three core fundamentals ready for their arrival: feed, water and air.

June 5, 2024

7 Min Read
National Pork Board

By Bradley Eckberg, MetaFarms

Mortality rates in swine populations are a critical indicator of overall herd health, management efficacy and economic viability in pig farming. Understanding and mitigating the factors that influence these death rates is essential for producers aiming to enhance productivity and profitability. Variations in mortality rates can stem from a myriad of factors, including genetics, disease prevalence, nutrition, environmental conditions and management practices. Wean-to-finish mortality rates continue to trend upwards year-over-year. In this article, we will look at historical trend averages, a closer look at the bottom 10% groups, and the performance impact that mortalities have.

W2F closed group analysis was performed utilizing the MetaFarms Ag Platform with specific focus on the United States customers only. In the calendar year 2023, the U.S. MetaFarms customers had slightly more than 4,000 closeouts (4,048) with nearly 10,500,000 total pigs started. A characteristic of a single-stocked W2F group would be a starting average weight around 12 pounds with an ending average weight out of 285 pounds.

Pigs are normally on feed for around 160 days, have an average daily gain of 1.65 and have a feed efficiency of 2.60. Single-stocked W2F groups were specifically analyzed to fully show the wean-to-market performance and mortality rates as opposed to the two-phase system of nursery and finishing groups which can lead to more noise in the data.

First, it is important to understand what makes up a single-stocked wean-to-finish group. When determining what a single-stocked group is, MetaFarms looks at a percentage of animals transferred out of a group. W2F groups that transferred (pigs moved from one active group to another active group) more than 10% of the pigs started, are removed from the benchmarking analysis. Removing these groups allows the remaining groups to be compared by performance and costs on a more “apples-to-apples” perspective.

The chart below shows the last 11 calendar years’ worth of W2F mortality closeout averages. 2024 data is comprised of closeouts between January 1 to May 31, 2024. The chart also shows the 11-year trend on the bottom 10% of closeout mortality rates. The bottom 10% of closeouts are based solely on mortality rates. For 2023, the bottom 10% would include 400 groups.


As previously stated, W2F closeouts continue to show rises in mortality rates with the 2023 average at 7.23%, which is up from 2022 by 0.36% but is higher than the 2016 average of 5.49%. That average difference between 2023 to 2016 is 1.74% or an overall percentage change of 31.7%.

If that was not eye-popping enough, the orange line shows how the bottom 10% of closeouts have also dramatically increased over the years. Percentiles does show the true changes across the large database that MetaFarms has. Since 2019, the bottom 10% mortality rate has risen by 2.67% from 9.76% to 12.43%, that’s a 30.7% change. The average mortality rate over this same period is a mere 1.28% or 21.5% change. What this shows is how, yes, the average rates are increasing. However, the bottom end groups are really having a tough time with keeping pigs thriving.

Bottom 10%

Continuing to focus on the bottom 10% groups, the chart below shows the last 11 years of average mortality rate and the overall number of W2F groups when compared all the groups. In 2023, 18.4% of all W2F groups closed out over 10%, whereas in 2019, there were 9.4% of all groups and in 2016 there were 7.3%.


The next four charts compare the year-over-year performance differences between the bottom 10% and the average for W2F closeouts. Here are a few key takeaway differences:

  • Feed conversion:  0.04 - 0.11 higher

  • Average daily gain:  0.06 - 0.10 slower growth rates

  • Average days on feed:  4.7 - 7.9 more days on feed

  • Feed cost per pound gain:  0.09% - 4.55% higher feed costs



Mortality by weeks on feed

The next chart looks at 2023 W2F mortality by weeks on feed broken down by closed group average mortality rates. The green line indicates the weekly percentage for the W2F groups that closed out with an average mortality rate of 20% or higher and represented 4% of all groups. The greater than 20% groups saw 73.4% of the death loss occurring the first nine weeks of the group. Furthermore, 43.9% of the loss happened between weeks three through six.  


The performance effect

Thus far we have looked a lot into how many and how often mortalities have occurred but now we will look at the performance impact of mortalities. The chart below shows the 2023 W2F mortality performance by mortality ranges. When looking at mortalities, it is important to understand when deaths are happening. Groups with late term losses will have a much larger impact on key metrics such as feed conversion and feed cost per pound gain.

When comparing performance between the <5% groups to the >=9% groups here are a few key takeaways:

  • Nearly 10% lower death loss average which directly leads to higher market sales

  • 4 pounds heavier out weight

  • 8.2 less days on feed

  • $0.02 cheaper feed cost per pound gain



More than likely the health of these wean pigs was less than ideal. Remembering back from my own W2F days, when receiving health challenged pigs, we would do whatever we could do to have the three core fundamentals of pig management ready for their arrival:  feed, water and air.  

  • Feed:  The right age-appropriate feed was available not only in the main feeder source but also in smaller bowls as well as mat feeding was done to allow for easy accessibility for each pig.

  • Water:  First thing we would do is ensure that the PH level was at the right level for the pig’s gut. For those barns that had cup waterers, we would crack the nipple to allow for a slow continuous drip of water which was meant to entice the piglet to drink without having to exert much energy to do so.

  • Air:  Ventilation for pig barns, especially W2F barns, can be a fit of a fine science.  Unlike a standard nursery barn that has plastic flooring, typically W2F barns have concrete flooring with deep pits underneath them. These two factors lead to the importance of warming up the barn well in advance of pig’s arrival as well as a barrier between the pig and the flooring. Also very important is the airflow itself. In the Midwest, winter temperatures can get cold and allow for more opportunities for pigs to be chilled and stressed. Be sure to understand how the air is coming in and out of the barn to not only have a warm comfortable environment for the pigs, but also energy cost savings for the producer.

Across the board, swine producers and veterinarians are working hard to minimize the unpleasant number of losses with research and data driven decisions on vaccination protocols, animal husbandry standard operating procedures, and as important as any, producing a high health quality pig out of the sow farm. Daily vigilance and persistence in teamwork and communication among all aspects of the swine industry will pay huge dividends in the end with more delicious pork consumed.

MetaFarms Analytic Insights were used to provide the context and trends for this article. If you would like to see an analysis of how your wean-to-finish mortality and performance compares to the industry, or if you have suggestions on production areas to write articles about, please e-mail or call us. We enjoy being a part of the National Hog Farmer Weekly Preview team. Previous Production Preview columns can be found on the website.

If you have questions or comments about these columns, or if you have a specific performance measurement that you would like us to write about, please contact Eckberg at [email protected].

Subscribe to Our Newsletters
National Hog Farmer is the source for hog production, management and market news

You May Also Like