Best of Leman 2019 #2: J. Nerem and J. Schwartz – Investigating silent estrus in gilts

Our second selection from the past Leman conference is actually two presentations from practitioners regarding silent estrus in gilts. Dr. Joel Nerem works in Pipestone Veterinary Services and Dr. Jake Schwartz is with Swine Vet Center. Both share their experience dealing with this issue.

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Exposing gilts to Mycoplasma hyopneumoniae using a herd-specific lung homogenate

The last issue of the Journal of Swine Health and Production featured a practice tip written by Dr. Rebecca Robbins from Seaboard Foods, in collaboration with Dr. Maria Pieters and the MycoLab. This publication has for objective to share a safe, reliable and herd-specific technique to expose gilts to Mycoplasma hyopneumoniae.

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Gilt management for improved sow lifetime productivity

A glitch in WordPress prevented this post from being released on Friday, so we are sharing it with you this morning. Sorry for the inconvenience, we are working with the platform to fix the issue.

This week, we are sharing a report by Drs. Patterson and Foxcroft about gilt management. Previously, we shared the recording of her presentation during the 2018 Leman conference. Below is an update on her work at the University of Alberta.

Key Points

  • Successful replacement gilt management starts at birth
  • A low individual birth weight and a “Low litter birth weight sow phenotype” are key factors determining the efficiency of replacement gilt production
  • Good gilt selection and pre-breeding programs remove early culling for reproductive problems as a factor in sow life time productivity

Gilt are the foundation of good production (Tubbs, 2015) and drive farm success (Ketchem and Rix, 2015).Low individual gilt birth weights have
been linked to increased preͲweaning mortality (Magnabosco et al., 2015), poor growth until finishing, compromised ovarian and uterine development (Deligeorgis et al., 1985), fewer pigs produced over three parities and earlier removal from the herd (Magnabosco et al. 2016). At sow level, a low litter “birth weight phenotype“(BWP) carries all the same risks as a low individual birth weight, but as a “litter” trait. As part of a National Pork Board-funded project to investigate links between litter BWP and sow lifetime productivity (SLP) conducted in collaboration with Holden Farms Inc., litter BWP was determined over at least two successive parities.

Multiplication sows (n = 651) were then classified as having either a low (L, < 1.18 kg, n=63), lowͲmedium (LM,> or = 1.16 to < or = 1.36 kg, n=281), medium-high (MH, > 1.36 and < or =1.6 kg, n=254) or high (H, > 1.6 kg, n=53) average litter BWP. Low BWP sows produced progeny with limited survivability after birth, poor retention during gilt development, and overall had a lower efficiency of replacement gilt production. Although BWP had a significant effect on weight and growth rate at the time of Pre-Selection (170 days), when puberty stimulation commenced at around 182 days of age, BWP did not affect the days to recorded first estrus.

Therefore, the growth performance of even the lighter gilts born did not delay the onset of pubertal estrus. Furthermore, for those low birth
weight pigs that survived and were selected as replacements on the basis of a recorded pubertal estrus event, a low BWP did not affect total pigs
born over four parities, or longevity in the sow herd. In contrast, gilts born in litters with a high BWP had lower retention rates in the sow herd.

Take home messages

Low birth weights affect the efficiency of replacement gilt production because these gilts either die, or are voluntarily non-selected because of relatively poor growth performance: However, if they survive, they have an equal chance of being bred and have better performance in the breeding herd that had high birth weight gilts.

Irrespective of gilt origin, earlier maturing gilts that have a recorded standing heat (HNS) within 30 days of starting boar exposure are the premium “Select” gilt population. They are inseminated earlier, have fewer non-productive days (NPD), are culled less due to reproductive problems, have higher farrowing rates, have more pigs born alive and are culled later (see Patterson and Foxcroft, 2019).

To be reliable and cost-effective, the stimulation program must involve daily direct contact between the gilts and high libido boars: This maximizes the “boar effect” and drives the efficiency in the gilt development unit (GDU). Adequate resources need to be allocated to the GDU (staffing, facilities, focus and time) and daily records of GDU performance should drive key management decisions (e.g. PG600 intervention). Only breeding-eligible gilts with a recorded HNS should be delivered to the sow farm or moved to the pre-breeding area. Breeding gilts at 2nd or 3rd estrus, at a target body weight of 135-150 kg, and after utilizing at least a 14-day pre-breeding “acclimation period” during which gilts are essentially on full feed, are the next crucial steps in optimizing SLP.

Take home message

Individual recording of gilt performance in the GDU is as critical as, and has longer-lasting consequences than, individual recording of breeding sow performance after weaning.

References are available on the original document.

Best of Leman 2018 series: J. Patterson – Efficiencies of replacement gilt management

Our fifth presentation is by Jennifer Patterson from the University of Alberta about how we can improve efficiencies of replacement gilt management.

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What are the acclimation practices for Mycoplasma hyopneumoniae accross the EU?

This new publication in the Porcine Health Management journal is the result of a collaboration between the University of Barcelona in Spain, PIC (Pig improvement Company) and the MycoLab at the University of Minnesota.

321 farms were surveyed across Europe and Russia regarding their practices for gilt acclimation especially in the context of Mycoplasma hyopneumoniae. The farms are spread over 18 countries and this is reflected in the strong variation of the measures taken to acclimate the incoming gilt population.

Among the questions asked, the type of farm as well as the size of the herd were recorded. Regarding the gilts, the researchers took into account receiving schedule as well as origin and age in addition to the acclimation measures.

In the table below, you can see the summary of  the measures taken to acclimate the gilts to Mycoplasma hyopneumoniae. The vast majority of the herds (77%) used vaccination either as a single intervention or coupled with exposure to sows about to be culled.  Another popular option (22.4%) was no intervention at all.

Acclimation methods for Mycoplasma hyopneumoniae across the EU
Number of farms (%)according to the methods used for replacement gilt acclimation in terms of M. hyopneumoniae

Click on the table above to see the full open-access publication.


Gilts are considered to play a key role in Mycoplasma hyopneumoniae (M.hyopneumoniae) transmission and control. An effective gilt acclimation program should ideally reduce M. hyopneumoniae shedding at first farrowing, decreasing pre-weaning colonization prevalence and potential respiratory problems in fatteners. However, information on gilt acclimation practices is scarce in Europe. The aim of this study was to identify current acclimation strategies for M. hyopneumoniae in Europe using a questionnaire designed to assess 15 questions focused on gilt replacement status,
acclimation strategies and methods used to ascertain its effect. A total of 321 questionnaires (representing 321 farms) were voluntarily completed by 108 veterinarians (from 18 European countries). From these farms, 280 out of 321 (87.2%) were aware of the health status of gilts on arrival. From these 280 farms, 161 (57.5%) introduced M. hyopneumoniae positive replacements. In addition, 249 out of 321 (77.6%) farms applied an acclimation process using different strategies, being M. hyopneumoniae vaccination (145 out of 249, 58.2%) and the combination of vaccine and
exposure to sows selected for slaughter (53 out of 249, 21.3%) the most commonly used. Notwithstanding, only 53 out of 224 (23.6%) farms, knowing the M. hyopneumoniae initial status and performing acclimation strategies against it, verified the effect of the acclimation by ELISA (22 out of 53, 41.5%), PCR (4 out of 53, 7.5%) or both (27 out of 53, 50.9%). This study showed that three fourths of the farms represented in this European survey have M. hyopneumoniae acclimation strategies for gilts, and one fifth of them verify to some extent the effect of the process. Taking into account that the assessment of acclimation efficacy could help in optimizing replacement gilt introduction into the breeding herd, it seems these practices for M. hyopneumoniae are still poorly developed in Europe.

Link to the full open-access publication