Demonstration of thermoregulatory control of piglets during farrowing by infrared thermography

Newborn piglets are extremely cold sensitive, being born with very little adipose tissue, no brown fat and very little, if any pelage. They lose heat rapidly once born and need to get to the udder and ingest colostrum quickly in order to increase their body temperature, as well as acquire immunity. The purpose of this study was to monitor piglet’ skin temperature continuously during farrowing, to better demonstrate the thermal compromise piglets face once born, without the need to disrupt maternal and piglet behaviour during farrowing by removing piglets for traditional methods of measuring temperature (e.g. rectal thermometers). A preliminary study was conducted within an existing research project on alternative farrowing systems. Sows gave birth in loose farrowing accommodation onto a solid concrete floor with a designated amount of straw bedding. The infrared thermal imaging camera, model Avio TVS 500 (thermal resolution better than 0,05°C, spatial resolution 1.6 mrad), was secured two metres above the nest pen at the time when a sow was beginning to show nest-building behaviour. A thermal image of the nest, sow and subsequent piglets was captured automatically every 20 seconds starting seven hours before and until 12 hours after the farrowing. Images obtained were analyzed using software specialized in processing infrared images (Goratec Thermography Studio), A thermographic video showing piglet’ skin temperature variation was created. Piglet’ skin temperature decreased from a maximum value of 39.5°C immediately at birth to just 31°C - 32°C ten minutes after birth, which was equal to the temperature of the straw near the sow. Concrete flooring not covered by straw bedding close to the nest varied in temperature between 18ºC - 20ºC.Piglet’ skin temperature started to increase only when they reached the udder and started suckling; taking more than one hour after birth to reach 35°C. To our knowledge, this is the first study using infrared thermography to continuously measure changes in skin temperature on pigs during farrowing. Thermography could provide highly detailed and non invasive measures on the multifactorial influences on piglet thermoregulation in the most critical time post birth and lead to an improvement in knowledge of the behavioural and physiological events that occur during this period. Thermography may better demonstrate the importance of micro-climate to buffer the piglet from immediate heat loss and therefore potentially give it extra time to reach the udder and suckle colostrum. In addition, this technique offers a useful, visual tool to translate scientific data into a visual medium for the producer.