Thermal comfort of sows in free-range system in Brazilian Savanna

• Published in: Journal of thermal biology 2020-02, Vol.88, p.102489-8, Article 102489
• Main Authors: Mós, João Victor do Nascimento, Nascimento, Sheila Tavares, Murata, Luci Sayori, dos Santos, Vinicius Machado, Neto, Antonio José Steidle, de Oliveira, Evandro Menezes, da Silva Lisboa, Áquila, de Freitas Silva, Luana
• Format: Article
• Language: English
• Subjects: Air temperature; Alternative system; Ambience; Animal behavior; Gestation; Physiology; Posture; Relative humidity; Respiration; Savannahs; Shade; Shading; Swine production; Temperature; Tropical climate
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2019.102489

The aim of this work was to evaluate the thermal comfort of sows in a free-range system in the Brazilian Savanna, based on behavior observation, availability of shading resources, meteorological and physiological variables. The sows were analyzed in the gestation sector at Água Limpa Farm from University of Brasília; the sows were housed in paddocks of 1000 m2 each containing artificial and natural shading structures, where air temperature (Tair, °C), wind speed, relative humidity (RH, %) and black globe temperatures (TG, °C) were collected for the environment characterization in 20-min-intervals. From the black globe temperature, the Mean Radiant Temperature (TMR, °C) and the Radiant Heat Load (RHL, W m−2) were calculated in the sun and under the shade structures. The total short-wave irradiance was calculated through the sum of direct, diffuse and reflected radiations. For the behavioral evaluation, an ethogram was elaborated, taking in consideration where the animals were in the paddocks, body posture, and the activity performed. The physiological variables such as respiratory rate (breaths.min−1), surface and rectal temperatures (°C) were measured during the experiment. The data was statistically analyzed through analysis of variance and frequency analysis. There was a difference at 11a.m., 2 and 3p.m., with values above 40 °C under the shade and above 70 °C in the sun for the TMR. The preferential choice was for natural shading by the sows, due to the lower TMR and RHL throughout the day and resting activity had been predominated. The rectal temperature did not differ between the animals and the days evaluated, respiratory rate varied according to air temperature, and surface temperature only among the evaluated animals. It was concluded that even when there is a greater radiation incidence and meteorological variables above the condition of comfort for sows, they did not express any abnormal behavior that could indicate discomfort. •High temperatures affects the behavior of the pigs in free-range systems.•High solar irradiation makes the sows prefer to stay under the shading resources.•In free-range systems, pigs were able to express natural behaviors to the species.