Post-cervical insemination in sows

What is PCAI?
Post-cervical artificial insemination (PCAI) is the insemination of sows with a semen deposition beyond the cervix directly into the uterine body. A regular AI catheter is first introduced into the cervix. This catheter then acts as a guide for a thinner cannula which is pushed through the regular catheter and beyond through the sow’s cervix. The semen tube, with usually a smaller volume than normal, is connected to the cannula and the semen is deposited into the uterine body. The whole procedure normally takes less time than a regular AI.
 
Which pre-conditions are important to respect?
One of the aims of PCAI is the reduction of sperm numbers and volume of the dose, so the quality of the semen is of major importance. Due to the lower amount of sperm cells in semen doses used for PCAI, there is no reserve left to compensate for mistakes in sperm production, and impaired semen quality. This makes the evaluation of semen quality crucial to assure a high AI success.

In addition, the semen quality must also be maintained on a high level during the transport and storage period. This can be done by using a high-quality semen extender, i.e., Androstar® Plus or Androstar® Premium. Both include CSP (Cell Shield Protection) to preserve the integrity of sperm acrosomes and membranes, especially in high dilution rates and sub-optimal storage conditions.

Several trials have shown that the volume and the number of sperm per dose can be reduced significantly when using PCAI. To not reduce the fertility level in a sow herd, a semen dose for PCAI should contain a minimum of 50 ml volume and 1 billion of motile sperm cells.

Further, a boar ejaculate does not only contain spermatozoa but also seminal plasma, the latter having a protective effect to the functionality of the sperm membranes and acrosomes as well. If semen is extended at high ratios for preparing doses for PCAI, a minimum part of seminal plasma should remain in the diluted semen. This can be assured if the whole ejaculate is collected during semen collection and not only the sperm rich fraction, which is poor in seminal plasma content.
 
How to prepare semen doses for PCAI?
  1. Collect the whole boar ejaculate to maintain a high level of seminal plasma in the ejaculate.
  2. Assure an exact evaluation of the semen quality. Use only ejaculates with minimum 80 % motile and morphologically normal sperm. An exact and objective evaluation with a CASA system, i.e., AndroVision® is ideal.
  3. Choose a high-quality extender that preserves the semen quality even in high dilution rates. A negative dilution effect can be alleviated by protective extenders like Androstar® Plus and Androstar® Premium.
  4. Prepare semen doses of 50 ml+ total volume, containing around 1 billion viable spermatozoa. To make sure that each semen dose contains the minimum number of sperm, it is important to maintain the diluted ejaculate well mixed during the filling process of the semen tubes and to prevent sedimentation.
  5. The cooling curve and storage conditions are similar to semen doses for regular AI. Bear in mind, that the lower volume tubes are more prone to temperature fluctuations because of the higher surface to volume ratio of the smaller tubes. 

How to perform PCAI?
The heat detection and the PCAI may be carried out separately. The intra-uterine insemination can be performed without the presence of a stimulating boar. The timing of insemination corresponds to the regular insemination.
 
  1. First, clean the vulva of the sow with a dry paper towel. Insert the PC Blue respectively the PC Clear catheter with its plastic protection bag 5 to 10 cm into the vagina of the sow. Then, push the outer insemination catheter through the protection bag. The tip of the inner PC cannula must remain completely inside the outer catheter.
  2. Now, push the catheter until it is fixed in the cervix of the sow. Take a break of at least two minutes. A longer break helps to relax the cervix for an easier penetration by the cannula. Within these two minutes, you can insert the outer catheters in other sows and then go back to the first sow and proceed.
  3. Then, with a slight pressure, start to push the inner cannula through the cervix of the sow into the uterine body. You may facilitate the process by slightly pulling the catheter and slightly rotating the PC cannula.
  4. Forward the PC cannula through the cervix. At a certain point, the cannula can be forwarded freely and then a resistance can be felt again. This is when the cannula passes freely through the uterine body until it comes across a slight resistance from the uterine walls. Insert the PC cannula at least 8 to 14 cm. If you use a PC Blue with stopper, you may fix the position of the inner cannula by attaching the stopper to the end of the Foamtip catheter. Then, connect the semen tube to the PC cannula. Now the semen may be inseminated.
  5. Let the semen flow into the uterine body by exerting a slight pressure on the tube. Normally, emptying the tube takes only a few seconds. The semen should flow freely. If a higher pressure on the tube is necessary, it can be helpful to slightly move the PC cannula in the uterus.
  6. Cannula and catheter may be withdrawn immediately after insemination. First remove the inner cannula completely out of the cervix. Then, remove both catheters from the sow.
 
Tips and tricks
  • The presence of a boar during PCAI insemination is not recommended. The stimulation of the sow by the boar causes contractions of the uterus which complicates the introduction of the PC cannula. Therefore, it is better to do the heat detection separately and not at the same time of the insemination. 
  • Gilts can mostly be inseminated after the third estrus with PCAI. The reproductive tract, and thus the cervix of younger animals is not yet sufficiently developed. 
  • The boar may be driven in the feed alley in front of the sows after the AI. The stimulation by the boar improves the sperm transport in the uterus of the sow. 
  • A good possibility for training PCAI is a uterus from the slaughterhouse. The procedure of this kind of insemination is easier to learn if one can feel the cervix passage and see it. The porcine AI training model Suzy offers a new approach by increasing the efficiency of AI training and enhancing animal welfare.
Post-cervical insemination in sows