<b>Thermoregulatory responses of female buffaloes reared under direct sunlight and shaded areas in the dry season on Marajó Island, Brazil

Abstract

This research aimed to assess the effects of dry season climate variables on Marajó Island, Brazil, on the thermoregulatory responses of twenty female buffaloes, assigned to shaded (SD), and unshaded groups (US). Data on air temperature (AT), relative air humidity, wind velocity (WV), respiratory rate (RR), rectal temperature (RT), and body surface temperature (BST) were recorded at 6 a.m., 10 a.m., 2 p.m., 6 p.m., and 10 p.m. The temperature and humidity index (THI), practical buffalo comfort climatic conditions index (BCCCIp), and practical buffalo environmental comfort index (BECIp) were calculated. At 10 a.m. and 2 p.m., WV was the highest. The RR of animals in both treatments differed only at 10 a.m. and 2 p.m. A difference in RT between treatments was seen at 10 a.m., 2 a.m., and 6 p.m. Significant changes were seen in the BST of animals in both groups at 10 a.m., 2 p.m., and 10 p.m. BECIp was different between the groups at 10 a.m. and 2 p.m., with higher values for the US group. Buffaloes are prone to thermal stress, particularly between 10 a.m. and 2 p.m., when the highest values of AT, THI, and BCCCIp was observed.

Water buffalo production in the Brazilian Amazon Basin: a review

“…In a study carried out on Marajó Island in the hottest hours of the day (2:00 pm) during the dry season, the respiratory frequency of buffaloes raised in an unshaded traditional system was 53.49 ± 20.48 compared to 30.30 ± 7.13 from buffaloes raised in a shaded system. Similarly, rectal temperature was higher when animals were raised in an unshaded traditional system especially during the hottest hours of the day (10:00 a.m., 2:00 p.m., and 6:00 p.m.), with values of 38.63 ± 0.50, 39.19 ± 0.59, and 38.65 ± 0.51°C, respectively (Joset et al 2018). These results showed that there was higher accumulation of body heat and more demand for energy for thermolysis in the buffaloes exposed to direct solar radiation, reducing the available energy for milk or meat production (Garcia et al 2011).…”

“…In addition, buffaloes possess a less efficient evaporative cooling system due to a rather poor sweating ability, consequent of their apocrine-type sweat glands, which are inefficient for body heat elimination (Marai and Haeeb 2010). Thus, under intense solar radiation, buffaloes may undergo a series of drastic changes in biological functions that include depression of feed intake, disturbances in water metabolism, impaired protein, energy and mineral balances, enzymatic reactions, hormonal secretions, and blood metabolites (Moraes Júnior et al 2010;Garcia et al 2011;Silva et al 2014;Joset et al 2018).…”

Key points for the thermal comfort of water buffaloes in Eastern Amazon

“…In tropical climate conditions, the respiratory rate of water buffaloes at rest is 18 mov min -1 , reaching 24 mov min -1 in the hottest periods of the day. As buffaloes have a low relative efficiency in heat loss through the skin, loss through expired air, characterized by an increase in respiratory rate, plays an important role when compared to sweating (GUdEV et al, 2007b;JOSET et al, 2018). In the Brazilian Amazon, buffalo bulls managed in an artificial insemination center had a respiratory rate of 21 to 23 mov min -1 , in the rainiest period of the year, increasing to 23 to 30 mov min -1 , recorded in the transition period (BARROS et al, 2015).…”

Dynamics of Thermolysis and Skin Microstructure in Water Buffaloes Reared in Humid Tropical Climate—A Microscopic and Thermographic Study

“…One of the most notable characteristics of buffaloes is their adaptative capacity ( 9 ). However, despite their adaptability to different environmental conditions, the water buffaloes have morphological peculiarities that impact the regulation of their body temperature (BT) ( 10 , 11 ), making them more susceptible to heat stress, particularly when submitted to environmental conditions of high temperature and relative humidity and/or intense direct solar radiation ( 12 ).…”