Thermal exchanges, physiological responses and productive performance of Guinea Fowl (Numidia meleagris) subjected to different air temperatures.

The objective of this research was to evaluate the thermal exchanges, physiological responses, productive performance and carcass yield of Guinea Fowl confined under thermoneutral conditions and under thermal stress. For the experiment, 96 animals were confined in 8 experimental boxes of 1 m2 of area, each, divided in equal numbers and placed inside two distinct climatic chambers, where the birds were distributed in a completely randomized design, with two treatments (air temperatures of 26 and 32 °C, respectively). For the collection of physiological responses and carcass yield 16 birds were evaluated and for the collection of data on feed and water consumption and productive responses, 48 birds per treatment were evaluated. The environmental variables (air temperature (AT), air relative humidity and wind speed), temperature and humidity index (THI), heat exchanges, physiological responses (respiratory rate, surface temperature, cloacal temperature and eyeball temperature), feed (FC) and water (WC) consumption and production responses (weight gain, feed conversion index and carcass yield) of the birds were evaluated. With the elevation of the AT, it could be noticed that the THI went from a thermal comfort condition to an emergency condition, where the birds lost part of their feathers, increased all physiological responses evaluated, and consequently, reduced by 53.5% the amount of heat dissipated in the sensible form and increased by 82.7% the heat losses in the latent form, increasing also the WC. ATs of up to 32 °C did not significantly affect the productive performance and carcass yield of the guinea fowl.

Estimation of heat exchanges in Boer crossbred goats maintained in a climate chamber.

Exposure of goats to high air temperatures can induce physiological and behavioral adjustments, increasing the dissipation of excess body heat in the latent form, and intensification of the use of these thermoregulatory tools can result in physiological and productive damage to animals. With this, the objective of the research was to quantify the levels of thermal stress and the sensible and latent heat losses of Boer crossbred goats submitted to different air temperatures, in a climatic chamber. Six male crossbred goats of the Boer breed, with an average weight of 25.06 ± 4.43 kg and mean age of six months, were grouped using a completely randomized design, with three treatments (air temperatures of the 26, 30 and 34 °C, respectively) and six replicates (animals) with 68% relative humidity. The temperature and relative humidity of the air were collected to calculate the temperature and humidity index (THI) and heat exchanges. Were collected the physiological responses rectal temperature (RT) and surface (ST) and respiratory rate (RF), with these data were estimated the heat exchanges by radiation (L), convection (Cr), total sensitive (Gs), latent of the respiratory tract (Er), cutaneous (Ec), total latent (Et) and total heat exchange (Wt). It was found that the THI values were classified as thermal comfort, moderate stress and very stressful, respectively, in the three conditions evaluated. With the increase in AT, the animals significantly increased (P < 0.05) the RT, ST and RF, and consequently reduced sensitive heat exchanges, from 38 to 8%, and increased latent heat exchanges, from 62 to 92%, when compared air temperatures of 26 and 34 °C, respectively. Physiological responses showed a significant negative (P < 0.05) correlation with sensitive heat exchanges and a positive correlation with latent heat exchanges. In very stressful thermal conditions, the animals lost almost all of the excess metabolic heat by latent means (skin and respiratory tract).

Ethology, physiological, and ingestive responses of sheep subjected to different temperatures and salinity levels of water.

The objective of this study was to evaluate the physiological responses, ethology, and ingestive behavior of female Morada Nova sheep kept in a thermoneutral environment, after thermal stress and after consuming water with different levels of salinity. Thirty-six Morada Nova females with a mean age of 10.0 ± 2.0 months and a mean weight of 25.0 ± 3.0 kg were evaluated and distributed in a climatic chamber. The experimental design was completely randomized, with a factorial scheme of 2 (air temperature (AT)) × 3 (salinity levels (SLs)) and six replications. The sheep's physiological responses, ethology (day/night), and ingestive behavior were evaluated while they were subjected to ATs of 26.0 and 32.0 °C and SLs of 3.0, 6.0, and 9.0 dS/m. With elevation in AT, the animals experienced increased (P < 0.05) rectal temperatures (RTs), respiratory rates (RFs), and surface temperatures (STs) and exhibited reduced (P < 0.05) heart rates (HRs). When consuming water with an SL of 9.0 dS/m, a HR reduction (P < 0.05) was observed. Sleep behavior increased (P < 0.05) with the increase in SL during the day. Sleeping and drinking behaviors increased (P < 0.05), and the time of inactivity was reduced (P < 0.05) during the nocturnal period with increased SLs. With increased SLs, sheep consumed more water (P < 0.05) and reduced (P < 0.05) the number of regurgitated ruminal boluses per day (NRBD). Under the conditions of thermal stress (32.0 °C), sheep need to make physiological adjustments to maintain homeothermy. Water consumption of SLs up to 9.0 dS/m causes a higher state of dormancy in female Morada Nova sheep.