After an average gestation period of 115 days (ranging from 112 to 117 days), the piglets are born. The signal to begin comes from the piglets themselves. In the majority of sows, restlessness and a nesting instinct can be observed shortly before birth, in the form of the sow interacting with enrichment materials. In some cases, increased physical activity may be observed. The sows often seek out more comfortable lying positions.

Farrowing takes place whilst lying down. The sow lies down in a quiet lateral position about an hour before birth, and abdominal pressing can be observed. If milk can be expressed in a stream, this is a good indication that birth is imminent. If distinct pushing contractions and an increased respiratory rate are observed, it is clear that the time has come.⁶ The duration of farrowing in modern high-performance sows is becoming increasingly prolonged. With more than 16 piglets, farrowing lasts on average 6.85 hours.⁷⁰ Sows that are able to move freely stand up at least once during farrowing for one to three minutes, usually between the first three piglets, and sniff the piglets. As the birth progresses, the sow remains lying down and rarely changes the side on which she lies, provided she is not disturbed. This also strengthens the mother-offspring bond. When a piglet is in the sow’s pelvis, she helps by pulling her hind legs in to facilitate the piglet’s passage. The intact umbilical cord prevents the piglets from straying too far from the sow whilst searching for the teats (rubber band function). The sow’s long tail also prevents the piglet from heading in the wrong direction. In doing so, the piglet uses the angles between the sow’s legs and hindquarters or belly as a guide. Piglets use the type and orientation of the bristles, the hardness of the body part (piglets seek soft teats) and the temperature (which increases towards the teats) as further ‘aids’ in locating the teats.⁷¹ To ensure the piglets find their way without difficulty, there must be no obstacles (e.g. piles of faeces/jute sacks) in their path. On the way to the teats, the sow’s hind legs present the first obstacle that must⁶ be walked round or climbed over (Fig. 17).

In the farrowing pen, it is important to work calmly and carefully to avoid startling the sow and thus causing her stress.

To prevent increased losses of suckling piglets, sows should be monitored regularly during farrowing. The main aim of this is to ensure that complications during the birthing process can be detected and treated at an early stage.

It is helpful to note down at the pen the time at which the piglets were born, how many were born, and whether assistance has already been provided or medication administered. This allows the progress and duration of the birth to be recorded, making it easier to identify stalled births objectively. Otherwise, it is easy to lose track, particularly in large sow herds and with large farrowing groups. If birthing problems are detected early, assistance can be provided in good time. Throughout the day, sows in the farrowing pen should be checked approximately every 30 minutes. Checks at night, or at least in the late evening and early morning, are also advisable to further reduce suckling piglet losses. Round-the-clock monitoring is very labour-intensive, as it requires more staff, but it can be worthwhile. Alternatively, as in the dairy sector, camera systems can make night-time monitoring easier (Fig. 18). Video surveillance is also beneficial for the sows, as the animals are not disturbed by the frequent comings and goings of the animal caretaker carrying out checks.

If farrowing always takes place at the weekend, birth monitoring is often reduced to the bare minimum. To make things more convenient for the animal caretaker, the weekdays for insemination can be chosen so that the main farrowing day falls within the working week. However, this often means that insemination must then take place at the weekend. Therefore, time slots with a high workload must fit into the farm’s individual work processes.