There are a number of factors that are in play when looking at the reproductive soundness of a potential replacement gilt. No matter what, we all want our sows to be happy, healthy, and at the same time product healthy piglets. In this article we will discuss the various factors that a pig farmer or pork producer should look for when choosing a replacement gilt. If you haven’t read our previous article on Choosing a Replacement Gilt – Feet Evaluation and are interested in raising pigs for your own freezer or to send to market, I would recommend taking the time to read it. So let’s get started.
Reproductive Soundness – Underlines
The underline evaluation is another critical step in the evaluation of replacement gilt candidates. Each sow must have functional nipples to raise pigs and it appears that both genetics and selection play a role in determining the spacing, prominence, and location of the teats. As many of us know, these traits do have a direct impact on production and it is recommended that all replacement gilts are evaluated for reproductive soundness.
The ideal underline should have seven (7) or more functional nipples on each side and they should be well spaced and well developed. Blind or pin nipples should not be present. We all love our pigs but discrimination should be applies when fewer than seven functional nipples are present on each side, blind or pin nipples exist, there is poor spacing and/or placement is present, or inverted nipples are present. The initial screening of teat number, spacing, and quality can occur at birth, weaning, or in the nursery but the final evaluation should be made when the selection of breeding gilts occurs.
|Fewer than six functional nipples on each side or presence of inverted nipples or poor spacing and prominence
|Six or more functional nipples on each side with adequate spacing and prominence
|Seven or more functional nipples on each side, well-spaced and well-developed with no pin or blind nipples.
Reproductive Soundness – External Genitalia
The external genitalia should also be evaluated on all replacement gilt candidates. Gilts should have a well developed vulva that is not tipped up.
- Cull gilts having an infantile vulva.
- These animals frequently have an under-developed reproductive tract.
- Gilts having a small vulva should be avoided.
- These gilts could have difficulty mating (particularly in a natural mating setting).
- Once mated, these animals could have farrowing difficulties.
- Tipped vulvas should be avoided
- Tipped vulvas may contribute to a higher incidence of metritis and cystitis.
Injured vulvas should be avoided as they could impair mating. Once the injury is healed the scar tissue that develops could also cause farrowing difficulties. You can allow the injury to heal and make an assessment at a later date, but ensure you use caution if you choose to let the injury heal and retain the gilt as a breeding herd female.
Other genetic conditions to avoid
Gilts producting offspring with these traits or that are from litters with the following conditions should not be selected as replacements.
- Scrotal Hernia – commonly called a rupture.
- Atresia Ani – missing the anus.
- Cryptorchidism – has at least one testicle that has not descended.
- Hermaphrodite – has both female (vulva) and male (penis) reproductive organs.
- Tremors – uncontrolled shaking.
- Splayleg – at birth, legs are straddled to the sides and the animal cannot stand on its rear feet
- Bent legs – pigs that have legs that have grown in an abnormal direction. Can be causedd by genetics or nutrition.
- Polydactyly – pig is born with extra feet, legs, and/or dew claws.
- Syndactyly – (mule foot), pig is born with one or more of its toes fused together.
- Thickened forelegs = pig is born with one or both front legs that are unusually thick (approximately twice as thick as normal)
Increasing the number of traits that are evaluated and used as selection criteria increases the number of potential canidates taht are needed to achieve the desired number of replacements.
If gilts are home-raised, the number of candidate females needed to supply replacement gilts to the herd determines the number of grandparent females needed in an internal multiplication system. The number of gilt candidates may not be a large problem if producers are purchasing their replacement females. Hopefully, most , if not all, of the culling has occurred prior to delivery of the replacement gilts to the producers farm. However, purchase gilts should still be carefully scrutinized before a producer places them in the breeding herd.
I hope you found this article helpful and would love to hear your feedback. Please leave a comment below and if you did find it helpful please share it on social media.