In intensive piggeries, sound hygiene can minimise disease problems and maximise production. A good standard of hygiene depends largely on the design of the piggery, management, routine cleaning and disinfection, and good housekeeping. Unhygienic conditions reduce the pig’s resistance to infection allowing disease problems to flourish.
Sensible piggery design, along with all-in all-out styles of management and pig flow, make an effective hygiene program much easier to use. Floors, walls and ceilings should be free from cracks and ledges so that cleaning and disinfection is more effective. Ideally, these surfaces should be constructed from materials that are resistant to chemical action, impervious to moisture and do not corrode.
Poor ventilation in any building affects hygiene. Increasing the air flow through the piggery will remove many airborne particles, which includes clumps of micro-organisms. This will improve the air quality inside the building and reduce the risk of respiratory disease. Bad ventilation can also lead to high humidity and poor air quality, resulting in bad dunging patterns. Bad dunging patterns further reduce the level of hygiene. Overcrowding, especially in hot humid weather, also lowers hygiene.
Stocking rate and stocking density.
Both stocking rate (m²/pig) and stocking density (m³/pig) influence hygiene. Unless current recommended levels are respected, it is difficult to maintain good hygiene and air quality. There are minimum stocking rates in the Model Code of Practice for the Welfare of Pigs (3rd edition).
The stocking rates in the code are minimums for each weight of a growing pig (based on a formula) and for other classes of pigs; a summary for growers is 0.22 m²/pig for pigs averaging 20 kg; 0.47 m²/pig for 60 kg; and 0.66 m²/pig for 100 kg for all indoor systems except deep litter. General practice is for pigs to be provided with a little more space than these minimums to cater for seasonal changes e.g. summer.
Airspace stocking densities.
Pigs per airspace: less than 300 per shed or room (if respiratory disease is present: Cargill)
All-in all-out systems (AIAO)
In AIAO systems, pigs of the same age (within two weeks) or class are housed together in a room or shed (age-segregated rearing) and arrive and leave about the same time. They may be weaners, growers or finishers, or may be sows due to farrow during the same week. The essential points of an AIAO system are that:
- all pigs are removed from the room or shed before the next group of pigs move in
- the facilities are thoroughly cleaned between batches.
Cleaning is one of the most significant factors affecting the improved growth rates and reduced levels of disease associated with AIAO production. A high-pressure hose can be used to thoroughly clean the space for the next batch, without the risk of wetting pigs or spreading micro-organisms to other pigs.
Another advantage of AIAO is that fewer pigs share the same air space i.e. stocking density (pigs/m 3 airspace). As air currents transfer micro-organisms from one pen to another, reducing the number of pigs in any particular air space can slow disease spread. Increased stocking density results in increased dust and bacteria levels, increased disease levels, and reduced growth rates.
A major aim of age-segregated rearing is to reduce the contaimination level in the shed to below the infective dose for each disease (so that the pig does not become sick), to eliminate contact between groups of pigs and to limit the stress on the pigs i.e. to improve the level of hygiene, air quality and temperature control. Conventional farrow to finish production, with continual flow housing in large open penned sheds, provides maximum opportunity for diseases to be spread from sows to their litters and from pig to pig in the growing phase. A factor in this is the contact between slower growing (unhealthy) pigs with younger faster growing (healthy) pigs.
AIAO can be by room, sections, building or even site to separate the groups of less than 300 pigs. Within a building, reduced pig-to-pig contact can be achieved by placing an aisle or empty pen between pigs, or using a solid pen wall at least 1.2 m high, a curtain to divide shed sections, a solid wall to the eaves or even the roof line; each step is an improvement and reduces the risk of disease spread.
The design of pens also influences hygiene. Fully slatted pens and partly slatted pens are best, followed by solid-floor pens with a separate drain. However, if fully slatted floors are used, then pits need to be flushed regularly; at least twice daily, otherwise ammonia and bacterial levels may become a problem. Deep pits, which can hold one to two weeks of effluent, should not have the level rising closer than 30 to 40 cm to the bottom of the slats otherwise bacterial aerosols may become a problem.
Partly slatted pens for groups of pigs such as growers should be long and narrow with slats at one end. Standing on the slats, a pig should be able to see other pigs in the next pen. The waterer should be over the slats.
Dry sow stalls.
The slats in dry sow stalls should be designed so dung does not accumulate behind the sows and urine does not form puddles. If there is a common feeding and watering trough, the stalls should prevent gilts and thin sows from turning around and urinating or dunging in the trough.
In well-designed farrowing pens, piglets dung and urinate over slats away from the creep area, which should be warm and dry. The creep area should be covered by a low roof with a solid floor surrounded by three solid walls. Drainage should be arranged so that spillage from the sow’s waterer does not wet the pen or creep area. The position and type of waterers and slats all influence the dunging patterns of the piglets. Well-designed pens should need very little cleaning while they are occupied.
Batch farrowing (groups of one age/stage e.g. a batch of sows due to farrow at the same time and fill the shed or room) will enable more effective cleaning in the farrowing house as it allows separation of ages and the AIAO system to be practiced. Increasing the gap between batches reduces the risk of disease spread between groups of pigs. The batches of sows’ farrow together, preferably so the litters have an age range of less than four days but no more than seven days. Farrowings can be weekly or fortnightly in large herds, and/or up to every five weeks in smaller herds.
Trough feeding is better than floor feeding. The design of the trough should prevent the pigs from walking, lying, urinating or dunging in it. Trough feeding weaners is strongly recommended.
Disinfectant footbaths have little value unless the fluid is changed at least daily.
How to clean pens.
- Remove and clean feeders and other equipment then remove all loose dung from the pen, walls and floor.
- Hose down walls and ceilings to remove dust and soak pen with water and detergent (a cleanser and solvent which makes caked-on material easier to remove).
- Soak heavily caked pens for 24 hours. Soaking the pens and using detergents reduces water use and cleaning time.
- Pressure-clean using a minimum 1000 psi (6900 kPa), ideally with hot water or steam. Take care not to damage concrete surfaces.
- When cleaning farrowing pens and weaner accommodation, ensure all piglets and weaners are protected or removed from adjacent pens to prevent chilling.
- Disinfect the roof, walls and floor with a spray disinfectant. Disinfectants are substances selected to kill infectious agents including bacteria, viruses and fungi. To save time and money it is essential to thoroughly clean the pen before disinfecting it as most disinfectants adversely react with organic matter.
- Disinfect the water system.
- Control rats, mice and flies by keeping the site tidy and free of overgrown grass and weeds.
Some herd operators flame the farrowing crates to help control coccidiosis.
(Cleaning pens information adapted from The Good Health Manual for Pigs, 1995, Pig Research and Development Corporation)
Colin Cargill and Tim Murphy,
Primary Industries and Resources,
Government of South Australia