Why We Came to Have The Dry Sow Stalls
Outside of the pig industry very few people know why dry sow stalls came into existence. It is time an honest overview is presented that takes the consumer through the journey that produced the dry sow stall, the most widely used means of housing dry sows in the world. Dry sow is a term used to describe non lactating sows, typically pregnant sows.
This article is written by a welfare passionate pig farmer whose 31 years in the Australian and New Zealand pig industries have allowed him to provide an understanding of the welfare issues that plague any sow housing system and why this led to the development of the sow stall in the first case. He now works for a company that only houses sows in an outdoor system but the majority of his career has been in large indoor farms in Australia and New Zealand where dry sow stalls have been the norm, though he has seen and managed piggeries where alternatives to stalls have been attempted.
About 40 to 50 yrs ago pig farming was heavily based on running sows in an outdoor environment. Farmers who sought to become efficient at supplying significant volumes of pigmeat to consumers found many problems with their outdoor systems of production of which many were welfare related.
These problems included:
- Parasites were hard to manage i.e. lice, round worm and whip worm. The worm eggs survive for at least 6 years in contaminated soil so reinfection was a real problem and the modern wormers weren’t available then.
- The climatic elements made it difficult to keep piglet mortality, or summer infertility in sows at respectable levels
- Predators were a significant cause of piglet mortality e.g. foxes in Australia
- Farrowing huts did not manage piglet mortality rates very well so numbers weaned were poor
- Difficulty in feeding sows to condition, especially during periods of rain on poor draining soil, meant that there was a wide variation in sow condition.
- Difficulty by stockpeople in accessing sows in open spaces meant that sick or injured animals were harder to treat
Farmers sought to manage the above issues by placing sows in groups under cover in sheds and on concrete floors. While most of the outdoor problems were far easier to manage or in fact eliminated, a new significant problem arose due to bringing animals into closer contact with one another and that was bullying. Pigs have a very strong hierarchical system (pecking order) and in adult pigs this is particularly ugly. I have seen sows die as a result of bullying or having to scale a 1.2 metre fence to escape an aggressive sow. Note that sows typically don’t like jumping hurdles. An even more obvious outcome of this aggression is vulva biting where a dominant sow will get her way, especially during times of feeding, by biting the vulva of other sows. It is very common in group housed sows for animals to have heavily mutilated vulvas.
Any caring farmer trying to manage such outcomes gets very upset by what they see. It is out of this situation that farmers tried housing sows in dry sow stalls, a device about 0.600 m wide and 2.000 m long and which prevented the sow from turning around. At the back of the stall was a slatted area where the dung and urine could pass through into a collection drain and at the front was a source of water and a feed trough. By preventing the sow from turning around it separated the dung, with the worm eggs, from the mouth of the pig and in so doing denied the worm the opportunity to complete its’ life cycle, thus reducing the reliance on worming chemicals.
This device allowed sows to be handled as individuals where the dominant and timid sow could be treated as equals and where the timid sow was not intimidated. We can all relate to that since who wants to have to fight Jonah Lomu and Mohammed Ali for a feed. It is much better for everybody involved for feed to be allocated based on body condition, the thin sow gets extra and the overweight sow, less.
The sow rewarded the efforts of those who managed the dry sow stall well with hugely improved production figures. She showed that where all of the vices that she had to contend with, were managed to produce on balance, a system of least stress, she would perform at increased levels. While there are situations where outdoor production will provide a better option because of a well drained soil type, in general, the dry sow stall has globally been the best technique to manage the multitude of problems that have faced pig farmers and their pregnant sows.
A common complaint made against the sow stall is that we as humans would not like to be housed like that and therefore neither should the sow. This translation of human expectations into an animals situation is called anthropomorphism. While many of us would like to be able to discard the sow stall on the grounds that we wouldn’t like it, me included, it is heartening for those of us who care for sow welfare and have worked in sheds where sows are housed in stalls during their whole pregnancy to see what happens when a sow accidentally unlocks the latch that keeps her back gate shut. Inevitably this happens at night and she will go a for a walk around the shed and often be found asleep the next morning in her stall with the back gate still pushed up in the air by her as she backed out during her earlier escapade. She obviously returns to where she feels happiest, in an environment where she is warm and secure. Maybe anthropomorphism in this case at least is not a good tool to judge sow welfare. Where it is appropriate though is where animals are housed in stalls near cold draughts, or a dripping tap in winter, or on poorly drained concrete, or with poor slats. In such situations there is no excuse for a farmer not identifying with his animals and so rectifying the situation.
More recently other techniques have become available that allow sows to be feed as individuals and yet roam around as part of a large group. Such techniques rely on electronic identification or the provision of individual feeding stalls that all the sows in a group are locked in while they are fed and then released to cohabit until the next feed time. Such systems typically require higher standards of stockmanship and so forcing farmers to use such systems can have negative welfare outcomes for sows. Unfortunately though there are no perfect systems adaptable to all situations and while the pig industry is forced to manage public perception and misinformation, simply demanding that sows be released from sow stalls will only negatively impact on sow welfare, a major reason why the stall was developed in the first case.
The pig industry has accepted that from the publics perspective the stalling of dry sows for their whole pregnancy is not acceptable; however without good alternatives that capitulation will not guarantee a better life for dry sows, indeed it will be a backward step for many sows who are forced back into the cheaper form of housing which is in groups. The managing of stress in the first four weeks of pregnancy is hugely critical to achieving a successful pregnancy so many farmers therefore wish to retain some stalls and have begrudgingly accepted a maximum of 4 weeks after mating to be the upper limit. I can understand their views on welfare grounds.
Idealist critics of indoor breeding who insist on running sows outdoors don’t know what difference soil type makes to managing sow and piglet welfare. New Zealand has few regions suitable for outdoor breeding and so such ideals cannot be satisfied throughout the country. These idealists fail to understand that we don’t live in a perfect world; even the antelope gets eaten by the lion, a terrible outcome for the antelope. Such is the outcome also for too many piglets and sows who are thrown into an environment when it is not well suited to outdoor breeding.
In closing I wish to comment on footage from TV1’s Sunday programme 17 May 09 of sows screaming and biting bars during the night filming. I have done night shift on large piggeries and never did I witness sows screaming unless I did something stupid like moving the feed trolley, even a few inches. Pigs are animals of habit and if they hear or smell something that suggests they are going to be fed, they will react as they always do and that is to scream until they are fed. Biting the bars is simply a means of venting their frustration of having to wait, just like a jostling queue of boys waiting to be served at a school camp.
Ian McIntosh (B.App.Sci.Rur.Tech)
