Thermal adaptability of neonatal piglets: Early life welfare crisis

Abstract

Homeothermic mammals can assert equilibrium in heat production and heat exchange with the ambient environment to maintain their body temperature through modification of physiology and behavior. However, the newborn piglets do not possess a well-developed thermoregulatory center resulting in a welfare issue, that is, piglet mortality due to hypothermia. Therefore, the present study was aimed to evaluate the early life welfare crisis of thermal adaptability of neonatal piglets. For this purpose, 127 newborn piglets were selected immediately after their birth. Rectal temperature (RT), which represents the core temperature of the neonate piglets, was recorded for three consecutive days from the second day of the birth. The first-day recording was avoided to minimize the disturbance of the farrowing mother. The RT was recorded for three days (second, third, and fourth day) at 0600, 0800, 1000, 1200, 1400, and 1600 hours of the day. Concurrently, the ambient temperature and relative humidity were recorded. The average RT increased significantly (P < 0.01) as the neonatal piglets became older. The cosinor analysis demonstrated significant (P < 0.01) rhythmicity in RT of daytime on all three days. Furthermore, the gradual reduction of acrophase value indicated the gradual gaining of thermal control of neonates. The daytime RT of neonates was positively (P < 0.01) correlated with the ambient temperature (r² = 0.301). The results indicated that the RT of neonatal piglets in the early days of life was modified as per the ambient temperature and their thermoregulatory system gradually developed as age increased.