Thermal stress index for native sheep.

The first objective of this study was to develop a thermal stress index for sheep based on environmental and animal data collected in a climate chamber under various environmental conditions. The second objective was to compare published indices of thermal comfort and the proposed index, testing them with the data from this study, with the objective of pointing out the most adequate index to be used by breeders when choosing management procedures. A total of 3024 data were obtained for the physiological variables of the sheep exposed to the eight thermal conditions in the climatic chamber and in ambient condition, kept three days in each thermal condition. A principal component analysis summarized the measurements of physiological variables into only one variable (y1). Using SigmaPlot software, multiple regression of y1 with the environmental variables and their combinations produced a number of indices. The equation chosen was the heat stress index for sheep, TSI = 24.153 - (0.0523*AT) + (0.746*BGT) + (4.104*Vp), with R2 = 0.668. The correlations presented high values, where these correlation values were assumed to indicate the efficiency of each index as indicators of the animals' response to the environment. Thus, it was assumed that the TSI presents a high efficiency.

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.