Thermoregulatory Responses of Heat Acclimatized Buffaloes to Simulated Heat Waves

Abstract

Climate change is seen as a significant threat to the sustainability of livestock production systems in many parts of the world, particularly in tropical regions. Extreme meteorological events can result in catastrophic production and death of livestock. Heat waves in particular can push vulnerable animals beyond their survival threshold limits. However, there is little information about buffalo responses to sudden changes in the thermal environment, specifically the heat waves. This study aimed to quantify the thermoregulatory and blood biochemical responses of heat-acclimatized buffaloes to a simulated heat wave. The experiment was designed in a climatic chamber with two periods of 4 days each. Twelve heat acclimated buffalo heifers aged 18 months were used. The climatic chamber environment was set as follows: 4-day period (P1) simulating the same weather conditions of a summer in humid tropical climate used as a baseline, with daily cycle with Ta and RH at 27 ± 1 °C and 76% from 0600 h to 1900 h and 24 ± 1 °C and 80% from 1900 h to 0600 h, and 4-day period (P2), simulating a daily heat wave cycle, from 0600 h to 1900 h with Ta and RH kept at 36 °C and 78% and from 1900 h to 0600 h, 27 °C and 74%. All animals were subject to both treatments and data were analyzed by a repeated measure analysis of variance, with post-hoc pooling comparison performed by Tukey’s test. In P2, there was observed a significant increase in respiratory frequency (p < 0.01), found four times in P1. The sweating rates were quite high in both periods; still, there were significant increases in P2 compared to P1 (p < 0.01) (4931 and 3201 g/m2/h, respectively). A slight but significant increase in rectal temperature was observed during the day (p < 0.01), with a rising until 1900 h. The simulated heat wave in P2 did not affect the values of the erythrogram or leukogram, excluding the significant reduction in K+ (p < 0.05). The low heat storage and the subsequent fast and full recovery of the thermal balance late afternoon appear to be related to the high sweating rate values. The massive sweating rate emphasizes its relevance in the maintenance of buffalo homeothermy. The absence of changes in hematological parameters has revealed the considerable physiological resilience of buffaloes toward simulated heat waves.

Water buffalo production in the Brazilian Amazon Basin: a review

“…This characteristic promoted the false idea that buffalo is a species that would have a high level of production under any environmental condition. However, the animal productivity is related to adaptability, and heat stress appears to be the major factor which negatively influences buffalo production in many parts of the world as Asia (Manjari et al 2015;Liu et al 2019), South America (Barros et al 2016;Galloso-Hernández et al 2020;Pereira et al 2020), Europe Africa (Megahed et al 2008). In this sense, the water buffalo, like any other species, needs to be properly managed in order to reduce exposure to adverse environmental factors and to guarantee its health, welfare, and a high level of productivity.…”

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

“…The relative air humidity recorded during the HTT favored heat exchange through respiratory evaporation, demonstrated by the pronounced increase in RR when the animals were under direct solar radiation, reaching maximum values of 116 mov·min −1 . The increase in RR is an essential thermoregulatory response to maintain homeothermy and is used by buffaloes as a proactive thermolytic response to prevent hyperthermia in heat challenge situations ( 65 ).…”

“…Shade enabled a reduction by 0.0427 W·m −1 h −1 in stored heat, which reflected in a difference of 0.31°C in internal BT when compared with the internal temperatures measured between Periods 0 and 3. According to Pereira et al ( 65 ), when in a thermal comfort condition, buffaloes exhibit a notable loss of body heat, provided by the reduction in stored heat.…”

Reliability of methods to determine cutaneous evaporative water loss rate in furred and fleeced mammals

“…It also automatically determines the measurement duration (~5–10 s) and signals completion with an audible tone. We used the original calibration that was certified and performed at the company laboratory, which represents what has commonly been done in previous studies (cattle, Scharf et al, 2008; dogs, Lau‐Gillard et al, 2010; sheep, Titto et al, 2016; buffaloes, Pereira et al, 2020).…”

“…These evaporimeters, originally validated for use on humans to determine transepidermal water loss (Nuutinen et al, 2003), are a convenient way to obtain instantaneous measurements of local CEWLs. They have been widely employed in studies with cattle, sheep, buffaloes, and dogs (Dikmen et al, 2008; Hamblen et al, 2018; Pereira et al, 2020; Scharf et al, 2008; Titto et al, 2016), despite never being validated nor calibrated for use in such mammals. A potential limitation of these methods is that the CEWL is measured in a closed chamber, and therefore is influenced by the microclimate near the skin surface (Imhof et al, 2009).…”