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How do cull sows respond to the transport to the slaughter plant?

New research from the Department of Animal Science, Aarhus University, shows that transport of cull sows to the slaughter plant in many cases involves a deterioration of the sows’ physical condition compared to before they were loaded on the truck. The results may play a part in improving animal welfare during transport and contribute to the debate about the concept of fitness for transport.

[Translate to English:] Udsættersøer ankommer til slagteriet. Foto: Carsten Kjærulff Christensen.
[Translate to English:] Udsættersøer ankommer til slagteriet. Foto: Carsten Kjærulff Christensen.


Pig production is characterised by increasing herd sizes and changes in the slaughter industry towards fewer and bigger units. This results in longer distances from the herd to the slaughter plant. As regards transport, cull sows may be more vulnerable compared to other swine categories due to disorders or weaknesses after several reproductive cycles.

“We know very little about how the transport to the slaughter plant affects cull sows. Previous studies have focussed on finishers”, says senior researcher Karen Thodberg, who ran the study.

As the first of its kind, the researchers at Aarhus University have completed a study of sows’ clinical condition before and after transport to the slaughter plant under commercial Danish conditions.

More than 500 sows from 12 herds were studied

The big observational study included 522 sows from 12 Danish herds. The sows were part of 47 loads of sows transported for up to 8 hours, depending on the distance from the herd of origin to the slaughter plant. Standardised clinical examinations of all sows were carried out in the herd and at arrival to the slaughter plant. The examinations included body temperature, respiration rate, body condition score, gait score and various injuries.

In addition, data on duration of transport, number and duration of stationary breaks during transport (sows were not unloaded) and temperature in the truck during transport were collected. On average, the sows were 5th parity (varying from 1-11), and nearly 40% of the sows were weaned the same morning and lactating on the day of transport. On average, the sows were transported 179 km, varying from 78 to 280 km. The journeys lasted from 46 minutes to almost 8 hours. The average temperature on the truck during driving was 14.1 °C, varying between 3.4 to 26.1 °C. The highest temperature measured in the trucks was 29.1 °C.

Deterioration during transport

Based on existing legislation, all sows were fit for transport before the transport, and 0.6% (3 sows) arrived at the slaughter plant in a condition, which would have been assessed as unfit for transport. Furthermore, the results showed that for several of the clinical measures examined before and after the journeys, a significant deterioration had happened in, for example, number of superficial skin lesions and wounds, gait score and signs of dehydration.

The European regulation rules for transport of animals says that “all animals shall be transported in conditions guaranteed not to cause them in jury or unnecessary suffering” (Transport Regulation, EU 1/2005). However, the regulation does not specify limits for “injury”, which makes it difficult to determine whether or not the deterioration of the condition of the sows in this study was inconsistent with EU’s regulations for animal transport.

“Our results highlight the need for more knowledge about the concept  of fitness for transport and for further studies of the importance of transport for the welfare of  cull sows , including development of methods which can optimise transport of pigs”, says senior researcher Mette S. Herskin.

Results may contribute to improved animal welfare

The researchers identified a number of risk factors connected to the deterioration of the sows’ condition: temperature and duration (often in combination) as well as duration of stationary breaks in the journeys and waiting time before unloading.

“Our results are important knowledge in relation to welfare of this group of animal during transport, and they also stress the need for the continuous focus on welfare challenges as regards transport of cull sows. Therefore, future studies should continue working on improving how to identify and separate risk factors and in that way develop procedures enabling transport of cull sows to the slaughter plant without risking their welfare”, concludes Karen Thodberg.

You can read the full scientific article: Transportation of Cull Sows—Deterioration of Clinical

Condition From Departure and Until Arrival at the Slaughter Plant


The research has been commissioned by the Ministry of Environment and Food of Denmark as part of the contract between Aarhus University and Ministry of Environment and Food for the provision of research-based policy advice at Aarhus University, 2017-2020.


Further information

Karen Thodberg, Department of Animal Science, Aarhus University
Email: Karen.Thodberg@anis.au.dk

Mette S. Herskin, Department of Animal Science, Aarhus University
Email: MetteS.Herskin@anis.au.dk