Modify the doors of the pen where the sows are group-housed.
This trick consists in improving the group-housed sows or gilts perception of the boar. After the ultrasound test, or after 28 days of pregnancy, the sows, that are initially stall-housed, are group-housed for the second stage of their pregnancy. Although in this stage the pregnancy diagnosis has already been made, there might be post-grouping pregnancy losses that can vary from a minimal percentage to high losses. In order to minimise the non-productive days of the sows that suffer abortions, it is important to have a good contact (visual, olfactory and auditory) with the boar for a quick detection of the post-loss heat.
In many cases, the pen where they are group-housed has a solid door. In this case we can make changes to favour a better contact with the boar in the corridor.
Using a simple drill and a hole saw for metal with a 4-5 cm diameter, we make several holes on the door, as seen on the photo. In this way, the pregnant sows and gilts in the pen will be able to perceive better the presence of the boar, avoiding entering the boar in the pen to check the heats. Also, the presence of the boar stimulates the progesterone production by the pregnant sows, ensuring a good progress of the pregnancy.