For several years now, post-cervical insemination has become common on most pig farms.

The correct procedure for post-cervical artificial insemination (PCAI) involves good heat detection. Once we have peformed the heat detection, we put the boar(s) away and wait a few minutes (often the time it takes to go get the semen doses is enough for the sow's level of stimulation to go down) and then we inseminate without the boar present.

To inseminate, we first clean the vulva. This cleaning is even more important here than with traditional insemination because the inner cannula will be introduced up to the beginning of the uterus, bypassing the first physical defense to contamination- the cervix.

We place catheters in four or five sows; this way we give the cervix time to relax, and we introduce the inner cannula. If the cannula does not enter a sow easily, we leave and move on to the next one to give her a little more time and then try again. Not all sows need the same amount of time to relax, but what is true is that the only sow that can make us wait ("waste time") is the last one.

Why is applying pressure to the semen dose important during postcervical insemination?

In a well-done PCAI, we deposit the semen in the uterine body, so we need less dose volume than with traditional insemination. In addition, we must consider that the uterus "hangs" inside the abdomen when the sow is standing. Therefore, the semen falls into the uterine body in a cascade. Thus, in a well done PCAI there cannot be any back flow whatsoever.

Therefore, in this particular insemination technique the fact of applying pressure on the semen dose acts as a quality control indicator for the process. If at squeezing the semen dose we observe semen backflow it means that we have placed the catheter and/or cannula incorrectly, and we will be depositing the semen in the cervix, instead of in the uterus. This is a sign that the insemination is incorrect. In this case we must "restart" the process, pulling back the cannula about 20 cm, repositioning the catheter, reintroducing the cannula, and inseminating again.

This is one of the major advantages of the post-cervical technique: at the end of the insemination you know if you have done it well or not. With traditional insemination on the other hand, back flow is much more variable and unpredictable, and therefore it is difficult to assess if insemination has been performed correctly.

You have often explained the importance of massaging the cervix in a circular motion at the end of the insemination. Why do you think this is so important?

In natural mating, when the boar finishes ejaculating and before the mating is finished, he performs some semicircular movements with his penis. The purpose of this movement is to "let the sow know" that ejaculation has ended and that she must move the semen towards the uterus.

The massage of the cervix aims to simulate this "signal". That is why it is important to partially remove the cannula when the insemination is finished, and to move the catheter itself (while still in the cervix) as if we were beating an egg for a few seconds. Often this is done incorrectly, moving the catheter while it is being removed, when the massage at the cervix should be a stimulation movement and not an extraction movement.

In addition, the massage has a second function just as important as the previous one. By massaging the cervix in a circular motion with the catheter, we stimulate the cervix again, so it will contract and we will see back flow if we have deposited the semen in the cervix and not in the uterus. Again, this is a measure that acts as quality control.

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