A gilt pig (or maiden gilt) is a female pig that has not farrowed a litter. Replacement gilts are female pigs that are yet to farrow a litter. Gilt pigs are primarily used for reproduction and are usually bred for the first time when between six and nine months old. Gilts not selected for breeding and are usually used for meat instead.

As gilt pigs are so important for a successful pig production operation, it’s definitely important that you know how to choose the best gilt pigs, as well as how to best care for them and replace them too.

First though, let’s take a difference between gilts, boars, barrows, and sows.

Gilt Pigs vs. Boars vs. Sows vs. Barrows

  • Gilt Pigs: Gilts are young female pigs that have not yet produced a litter of piglets
  • Sows: Sows are female pigs that have produced one or more litters. Gilts, therefore, turn into sows after breeding or having a litter
  • Boars: A boar is a male pig that has not been castrated
  • Barrow: A barrow is a male pig that has been castrated or is otherwise incapable of reproducing before reaching sexual maturity. Despite this, barrows still grow faster than gilts. If castrated once sexually mature, the pig is referred to as a stag

How to Choose the Best Gilt Pigs

If you are planning on purchasing gilts, it isn’t a good idea to go to a herd that has a high average performance in a particular trait that you want and then pick one at random. There are several things that you should look out for instead of just one solitary factor.

Production performance

Gilts should be selected on their growth rate and lean and fat composition – i.e. their production performance.


Teating is arguably the most obvious factor on which to base gilt selection, but it’s important that you pay closer attention to the number, shape, placement, and size of teats.

You want to make sure that a gilt possesses at least seven evenly spaced teats on either side, which start well forward and are in a straight line.

At all costs, you should avoid gilts with blind teats because this is an inherited defect that will stop a gilt from being able to supply milk to the piglet. Gilts with physical damage to the teats should also be avoided.

While you can still pick gilts with short, thick teats, this is less desirable than longer thinner teats because piglets will struggle to suckle short teats.

Conformation, Legs & Feet

Gilts should have strong legs and feet without any sign of weakness. They should be wide through the hindquarters, and pasterns should also be strong too.

If you are in any doubt about the physical characteristics of a gilt, make sure that she is not kept as a breeder. If kept for breeding, breakdown later in life can cause piglet losses and loss of productivity.


If a gilt is overly aggressive then she should be avoided as a future breeder. Many problems at farrowing time can be avoided if you select a gilt that is quiet yet active and alert.

Caring for Gilts

In order to build up immunities to any organisms present in the breeding herd, gilts should be housed in groups before being mated. Vaccinations for common diseases like mycoplasma, E. coli, leptospirosis, erysipelas, and parvovirus should also be undertaken.

Additionally, it’s wise to expose selected gilts to stimulate them to cycle earlier. This should be under supervision to mature boars for 20 minutes a day.

As an alternative, you can move weaned sows into the gilt pool because their urine acts as a stimulus due to containing estrogen. Using vasectomized boars is another alternative.

Feeding Gilts

When it comes to feeding gilts, you want them to be in good condition but not too fat. The goal should be to fatten gilts up to about 270–300 pounds by around 28 weeks old at which they are ready to mate. Make sure that you also purchase the best pig feeder for the job too.

A special feeding program is usually used to get gilts up to the required weight, especially because “thin sow syndrome” and a gilt’s subsequent breakdown can occur as her fat cover becomes depleted over subsequent pregnancies.

Replacing Gilts

Due to fluctuations in the number of farrowings, which can cause management problems with overcrowding or understocking, replacement gilts should be brought in regularly. However, you shouldn’t bring in too many at one time because large groups of gilts coming into farrow together can cause problems.

It can be hard to give an exact number for how many gilts should be brought in, as well as when they should be brought in too, but you can use farrowing and “expected” mating charts as a reliable indication.

What we will say, though, is that sows are usually most economically productive at around 3–4 years, which are their second to seventh (inclusive) litters.