When visiting a pig facility it is necessary to have a toolbox of indicators to detect heat stress. There are many indicators available, both environmental (risk factors) and animal based, of which some show an acute, others a longer term effect (pen fouling) of heat stress. Individual indicators are not sufficient as a signal for heat stress, a combination of indicators is a better proof. The most useful and proven indicators are described in more detail in three indicator factsheets (see ‘Show more’).
Useful indicators for (the risk for) heat stress:
Panting and changes in respiratory rate: Changes in respiratory rate and panting are thermoregulatory behaviours which can indicate heat stress. Pigs have a very limited number of functional sweat glands. Therefore, the major way pigs thermoregulate is via behavioural adaptation, e.g. increase in respiratory rate.
Pig fouling: When pigs are dirty through manure/faeces on the body, this is due to inappropriate behaviour arising from unsuitable conditions on the farm, such as thermal stress, bad ventilation, overcrowding or pen and/or flooring design.
Ambient temperature and relative humidity: The upper limit of the thermoneutral zones of pigs is as low as 25°C in the end of the finishing period. For lactating sows the thermoneutral zone already ends at 21°C, heat stress starts beyond this temperature. High humidity will aggravate heat stress due to the reduced ability of the pigs to use evaporative cooling (e.g. by panting).
Source photo: ©WUR