Design requirements

Size - Width 0.5 - 0.68m. The smaller width of stall is used for gilts to prevent them turning around and defecating in the trough at the front. If this occurs enteric diseases then become a risk particularly porcine enteropathy and salmonella. Length - 2.28m. If the rear part of the stall is slatted, gilts housed in long stalls will tend to defecate on the solid concrete area leading to sore legs and other leg problems.

A short stall side 1.2m long is used for tethers, the width the same as the stall.

Rear gate - Ideally this should be made of vertical bars so that faeces and urine can spill away from the back of the slats. Care is required however to make sure that the bars do not cause pressure sores. Where solid rear gates are used their bottom edges should be raised 80mm above the slats so that faeces cannot build up, contaminate the vulva and lead to vaginitis and endometritis (but not too high to cause pressure sores). The height of the rear gate should be sufficient to prevent the sow from sitting on top of it. Out breaks of rectal prolapse and abortion have been associated with this.

Floors - These may be totally slatted, part slatted or totally solid. Totally slatted floors are not recommended. They are uncomfortable for the sow and create difficulties when the sow stands, increasing the incidence of leg weakness. On part-slatted floors the solid area should be approximately 1m at the front and the remainder slatted. The slats should be 80-100mm wide and with a gap of 10-25mm and run parallel to the sow to provide a better less traumatic surface for the feet. If sows are housed on solid floors there should be a 1:20 fall in the last 300mm of the floor. This allows drainage of urine and easy removal of faeces. If the whole length of the floor slopes to the back it may predispose to vaginal prolapse and in gilts and second litter females a predisposition to osteochondrosis or leg weakness. All the accessible concrete edges should be round and not sharp and the surfaces of the slats flat and not sloping to the gaps.

Bedding - If bedding is used the faeces and urine soiled material must be removed from behind the sow daily.

Water - Fresh water should be made available to the sow in a trough at the front after each feed. If this is supplied manually, it may be necessary to provide extra in hot weather. A drinker may also be provided but it can leak producing wet floors that result in skin sores. A shortage of water will predispose to cystitis pyelonephritis and increased sow mortality.

Feeding - Sows may be fed once or twice daily, preferably once a day to prevent agitation and anticipation in sows awaiting their second feed. From a welfare point of view automatic dispensers held in front of each sow are best so that all animals can be fed at the same time. This will reduce the risk of torsion of the intestines, trauma due to excitation and stress associated reproductive failure.

Group size - There are no constraints on the numbers of animals held in any one building.

Temperature requirements - 18-20ºC (64-68ºF).

Management, welfare and disease

If you keep a sow in a stall or tether she is totally confined and has no control over her environment. It is therefore important the stall is long enough, (some modern-day prolific sows grow too long for standard stalls), the floor is comfortable to lie on, she has sufficient feed to satisfy her appetite, the environmental temperature remains constant day and night and there are no draughts. You can tell whether you are achieving these if you quietly open the door to the dry-sow house when no pig persons have been present for a period. Over 95% of the sows should be lying down on their sides.

The majority of sows lie down most of the time and will only rise to drink, urinate, and defecate at feeding time. This leads to problems such as cystitis and pyelonephritis. If they are only fed one main meal a day, the ration should contain sufficient fibre to satisfy appetite and keep the faeces soft. It is advisable to stimulate all sows to rise at least once a day by walking the boar round or sprinkling small quantities of feed into the water in the troughs.

All animals should be examined daily in a standing position to detect any signs of lameness or leg weakness. Additionally feet, legs, shoulders and hips should be examined for any sores, swellings or granulomas. At least twice a week neck or girth tethers should be checked and adjusted as necessary. Every two to three weeks an assessment of body condition and body score should be carried out. The skin should be examined for evidence of lice or mange. A frequent examination should be carried out of the slats, to check that they are not worn and causing trauma to feet and legs. All metal work and rear gates should be examined regularly to check there are no parts likely to cause trauma. A maximum and minimum thermometer should be checked daily to ensure that the sows are being maintained within their comfort zone. A minimum of 14 hours of light should be available to maintain a constant photo period and reduce the predisposition to abortion. If sows are weaned into stalls or tethers, both feed and water should be available at all times and the floor must be kept very clean and well drained. If straw is used keep surfaces well bedded to prevent udder contamination and the development of mastitis. A combination of the above factors can often be responsible for embryo reabsorption, abortion and heavy culling rates, resulting in persistent low farrowing rates.

Arguments for and against confinement

Sow stalls and tethers provide 4 of the 5 freedoms. They also allow individual sow examination, controlled feeding, and handling (e.g. treatment). The criticism levelled against them is that they deny the freedom to express normal behaviour and can lead to abnormal stereotypic behaviour such as bar biting. Thin sows can develop "bed-sores", leg bones can become softer and more readily broken than those of loose-housed sows and being less fit they farrow more slowly. In addition, tethers can result in neck or girth sores if not regularly checked and adjusted. They can however serve a welfare-friendly purpose if used for short periods e.g. to hold aggressive sows at weaning and during oestrus or to hold a sow for treatment for a short period.