Pigs (England): Code of Recommendations for the Welfare of Livestock: Pigs (PB7950)

Section 1 - Accommodation

Ventilation and Temperature

The Welfare of Farmed Animals (England) Regulations 2000 (S.I. 2000 No. 1870), Schedule 1, paragraph 13 states that:

- air circulation, dust levels, temperature, relative humidity and gas concentrations shall be kept within limits which are not harmful to the animals.

The Welfare of Farmed Animals (England) (Amendment) Regulations 2003 (S.I. 2003 No. 299), Schedule 6, Part II, paragraph 17 states that:

Pigs shall not be kept in an environment which involves maintaining high temperatures and high humidity (known as the sweat-box system).

52. All new buildings should be designed with the animals comfort in mind, and with the aim of preventing respiratory diseases. The buildings should provide enough ventilation throughout the year for the type, size and number of stock to be housed in them. In addition to meeting the ventilation requirements, the system should be designed to avoid draughts affecting the pigs living space.
53. Effective ventilation is essential to the well-being of the stock as it provides fresh air, removes noxious gases and aids in controlling temperature. Excessive heat loss should be prevented either by the structural insulation of the external walls, roof and the floor in the lying area, or by the provision of adequate bedding. Heat gain to buildings in hot conditions will be minimised by the insulation in the walls and roof.
54. Pigs have a very limited ability to sweat and are acutely susceptible to heat stress. Possible cooling methods, including blowing air over the pigs in a part of the pen, providing water spray/misting systems or simply wetting part of the floor with a hosepipe, can be used to ensure that pigs in buildings do not become overheated in hot weather. There should always be some dry lying area available as a matter of choice so that the pigs can move away from the cooler conditions.
55. Liveweight, group size, floor type, air speed and feed intake markedly affect temperature requirements and you must take these factors into account when determining the minimum temperature appropriate in each case. Slatted floors and low feed levels generally increase temperature requirements whilst straw bedding, high feed levels and higher body weights decrease requirements. For most circumstances, an appropriate minimum temperature can be found within the range given below:
Category of Pig Temperature
(C) (F)
Sows 15 - 20 59 - 68
Suckling pigs in creeps 25 - 30 77 - 84
Weaned pigs (3 - 4 weeks) 27 - 32 81 - 90
Later weaned pigs (5 weeks +) 22 - 27 71 - 80
Finishing pigs (porkers) 15 - 21 59 - 70
Finishing pigs (baconers) 13 - 18 55 - 64
56. You should avoid wide or abrupt fluctuations in temperature in housing systems within any 24-hour period. Wide fluctuations in the daily temperature regime can create stress that may trigger outbreaks of vice, such as tail biting, or disease such as pneumonia. You should maintain a higher than normal level of vigilance at these times.
57. When pigs are moved to new accommodation, the possibility of cold stress occurring as a result of sudden changes in the thermal environment should be reduced. This can be done by ensuring that the pen is dry, by the provision of bedding, such as straw, or by preheating the building.
58. When you are removing slurry from under slats, you must take special care to avoid fouling the air with dangerous gases (such as ammonia), which can kill both humans and animals. Buildings should either be empty or very well ventilated during this procedure.
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