Do All Gilts Lead The Way?

Reviewing the data on a gilt’s performance in her first parity can help producers understand possibilities for her future performance.

By Sasha Gibson

Using gilts’ performance to gauge future health and production makes sense. The gilt and litter (parity) 1 journey become the building blocks of the parity 2, parity 3 and parity 4 sow.

Gilts are 20 percent of our herd inventory at any time and equate to our third-highest operational cost, following feed and labor. Gilt performance is often “lumped in” with that of sows when considering operations on a week-by-week basis.

Producers have many ways to raise a gilt – researchers like George Foxcroft, Kenneth J. Stalder and Robert Knox have all identified techniques to maximize a gilt’s lifetime performance. Each farm does gilt entry slightly differently, based on some of the research principles outlined by the universities.

Producers make significant investments in rearing gilts. Farmers design standard operating procedures with a variety of animal factors, such as genetics, age at purchase, health, age at breeding, and boar exposure plan, in mind. Producers generally target a 47 to 50 percent sow replacement per year.

Pig production, however, is also very dynamic. Producers often have to modify the gilt flow from the way it was intended due to PEDv, PRRS, mycoplasma elimination or other disease challenges.

As a result, the animals may experience overcrowding and deviation from the planned “gilt experience.” For example, overcrowding can lead to more aggression, or less acclimatization to the sow farms before being bred.

Producers are striving for gilts to have at least four productive litters (Hoge et al., 2011). If not carefully monitored, unplanned challenges can affect the future sow farm performance.

If not segmented by parity, weekly production reports can hide poor gilt performance – it is easy to overlook an ongoing gilt problem. Often, producers review the number of bred gilts. If those figures are on track, we consider the gilt program good – but is it?

When reviewing reports, consider the animal’s age – is the gilt flow running as designed? If the farm is making target but the average bred age has shifted – either up or down – from the planned age, long-term effects could include fewer total born, lactation failure and longevity issues.

Are the gilts cycling at the predictive days after their entry into the farm? The plan of entry (weekly or monthly) should have a predicted number of heat no service (HNS) events associated with it. What is the target for your farm? If the number of HNS events moves, why did this happen? Such shifts indicate a change to the production flow before the gilts were even bred!

July to Dec 2016 Parity 1 litters liveborn and subsequent performance

Commonly, producers use parity reports to evaluate gilts. This report details the performance of each parity over a certain time period. You might, for example, want to consider how parity 1 sows cycled post-weaning compared to parity 2 sows.

A weekly performance trend analysis filtered by gilts (parity = 0) and sows (parity 1+), however, will give you the ability to address problems more quickly.

Productivity analysis is a newer report that tracks the number and percentage of gilts that entered the farm but did not get bred and so left the farm. This report also tracks the number of gilts that were bred and then left the farm. This data is important for evaluating gilt performance.

Data from over 300,000 gilts in 2017 shows the variation across operations in the percentage of gilts that entered and left the farm before they were bred. (PigCHAMP users across North America provided this data.) The reason for this gilt removal could be death or cull.

2017 average percet removed before breeding

These gilts were moved, tagged, vaccinated and fed. Ultimately, however, they were not bred. On average, producers removed about 6 percent of gilts before they were serviced. These are the “lost-dreams” gilts.

2017 average percent removed after breeding

After breeding, the farms in the database had an additional 6.7 percent of gilts leave the barn, either as a dead or cull. All of these animals incurred breeding costs prior to removal. These are the “broken-dreams” gilts.

These data sets are not a cohort. Rather, they are a moment in time. Overall, however, of the about 300,000 gilts that came into the nine databases or were bred on the farms, approximately 13 percent did not farrow.

The productivity analysis can quickly and easily show how your farm’s gilts are performing. You can use this data to evaluate planned and non-planned management changes to the gilt flow.

This figure indicates how long the served gilts are on the farm, on average, before they are removed. The average entry to removal service is 78 days, according to the 2017 data. Of the seven databases evaluated, one operation had an entry to removal rate of just 44 days, while the highest was 102 days.

Ryosuke Iida et. al (2015) found that lifetime performance was linked to performance in parity 1 sows. Considering that all parity 1 animals should not stay with the herd but, rather, that some should be pushed out is a different way of thinking. After all, the cost to get the parity 1 in the herd is high. But the cost of their sub-par performance may be higher. Are these gilts the animals that are more likely going to cost us in other areas too?

Subsequent litter performance data should make us pause. Based off the correlation between lower total born in the first litter and born alive in all farrowings, should a parity 2 sow be culled if a new gilt can replace her in a cost effective way?

percent of parity 1 farrowings with less than 10 total born first litter (July-Dec 2016)

This dataset uses total born at first farrowing and examines gilts farrowed between July and Dec. 2016. On average, 14 percent of the parity 1 gilts had less than a total of 10 piglets born. (This figure ranges from 11 to 17 percent for each farm). Using the liveborn numbers over the subsequent farrowings, can we make predictions of lifetime performance? (Note: this relationship is specific to total born and liveborn, not liveborn and liveborn, or total born and total born).

July-dec 2016 total born at parity 1 and subsequent cumulative liveborn farrowing performance

The subsequent liveborn over the 18 months following the first litter (parity) shows what has happened so far over the sow’s lifetime (five litters). Litters with total born above 20 were excluded from the analysis.

Gilts that had fewer than 10 total born in their first litters had 10 or fewer liveborn pigs in their first litter farrowing, as expected. Subsequently, however, these gilts produced an average liveborn of 10.1 in their next farrowing events.

Sows that had 11 or higher total born in their first farrowings had liveborns that averaged 13.8 piglets in their subsequent farrowing events. By Dec. 2017, some of the sows in the study had five litters.

The data suggests that total born in the first parity may be predictive of future farrowing liveborn events.

July-dec 2016 total born at parity 1 and subsequent liveborn farrowing performance at parity 2

Focusing on the data from just the first and second litters, we see a 1.5-pig difference on born alive at their second farrowing, when using total borns less than 10 on the first litter (parity 1) as a predictive value. On average, females that had less than 10 total born in their first farrowings had 11.9 born alive in their second farrowings. Sows that had 11 to 20 piglets in their first farrowing averaged 13.4 born alive in their second parities.

Low total borns in the firstparity seem to be a predictor of less liveborn pigs over the sow’s life.

After reviewing this data, some questions arise. Are the parity 1 females that have fewer total born more likely to leave the farm sooner than their peers? Are these animals more likely to be treated, or at risk for, being returns, late weans, mortalities, etc.? Do they lead us down the wrong path in more ways than just born alive?

If your current gilt supply and source are stable, and production has been in control, analyzing subsequent litter performance information on your farm may enable you to make the sow herd more efficient. Removing poor performers may allow other key performance indicators, such as wean to service intervals, return rates and mortality rates, to be improved.

These gilts that lead with high total born and liveborn may ultimately be the “future-dream” gilts.

Sasha Gibson
Sasha Gibson, originally from Glossop, Derbyshire, England, has been passionate about swine reproduction since gaining her master’s degree in pig production from the University of Aberdeen, Scotland. She works with nine swine veterinarians at the Fairmont Veterinary Clinic in Fairmont, Minn. She focuses on training, safety and production. Gibson has presented at several national and international conferences, including the American Association of Swine Veterinarians.

The Fairmont Veterinary Clinic’s mission is to provide leadership and knowledge to swine producers. Principles include maintaining a balance between animal well-being, economics and people, without compromising integrity. Fairmont also focuses on providing customized options for health, management and production issues. Contact us at 507.238.4456, fmtvets.com, or follow us on Twitter @fvcpigs.