How does Spix's yellow-toothed cavy (Galea spixii Wagler, 1831) face the thermal challenges of the Brazilian tropical dry forest?

The aim of this work was to investigate the thermal biology of the Spix's yellow-toothed cavy (Galea spixii) from the hot and dry environment of the Brazilian Caatinga by infrared thermography and biophysical equations. We monitored the rectal temperature, as well as the non-evaporative (radiative and convective pathways) and evaporative heat exchanges of males and females. The mean rectal temperature of females and males was 37.58 ± 0.02 and 37.47 ± 0.02 °C, respectively. We identified thermal windows by infrared thermography. The surface temperatures and the long-wave radiation heat exchanges were higher in the periocular, preocular, pinnae and vibrissae regions, in that order. The surface temperature of the periocular and preocular regions correlated positively with rectal temperature. Convective heat exchange was insignificant for thermoregulation by G. spixii. Evaporative heat loss increased when the thermal environment inhibited the radiative pathway. Females showed higher evaporative thermolysis than males at times of greater thermal challenge, suggesting a lower tolerance to heat stress. Therefore, infrared thermography identified the thermal windows, which represented the first line of defense against overheating in G. spixii. The periocular and preocular surface temperatures could be used as predictors of the thermal state of G. spixii.

Perfil hematológico de cães em diferentes concentrações de anticoagulante e bioquímica sérica em tempos diferentes de armazenamento / Hematologic profile of dogs in different concentrations of anticoagulant and serum biochemistry at different storage times

O objetivo deste estudo foi verificar as alterações hematológicas e bioquímicas em amostras sanguíneas de cães, em diferentes concentrações de anticoagulante EDTA-Na2 e diferentes tempos de armazenamento em temperatura entre 4 e 8°C por até 48 horas. Para isso, foram coletados 12mL de sangue por venopunção jugular ou cefálica de 30 cães (Canis lupus familiaris), procedentes do atendimento clínico realizados no Hospital Veterinário da UFERSA - Mossoró-RN. As amostras foram distribuídas em 4 tubos de ensaio, sendo 3 tubos contendo 50uL de EDTA-Na2 para a análise hematológica, preenchidos com 1mL, 3mL e 4mL, e o quarto tubo, para análise bioquímica, sem anticoagulante, foi acondicionado 4mL da amostra. As análises foram realizadas durante a primeira hora, 24 e 48 horas após a coleta. Posteriormente às análises, observou-se que as variáveis hematológicas se mostraram estáveis ao longo do tempo e independente da concentração de anticoagulante, sem diferenças significativas. Os resultados revelaram que a relação sangue/anticoagulante não interfere nos parâmetros do hemograma quando mantidas em condições adequadas de armazenamento e processadas em analisador hematológico Scil Vet abc™. Quanto às análises bioquímicas, submetidas às mesmas condições de armazenamento, também se mostraram estáveis por até 48 horas. Desse modo, conclui-se que as amostras sanguíneas podem ser armazenadas entre 4°C e 8°C por até 48 horas.

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment.

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R S-W, W m(-2)), were recorded. The R S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R S-W remained below 500 W m(-2). The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m(-2), the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R S-W exceeded 700 W m(-2). The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R S-W were recorded (815 and 958 W m(-2), respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m(-2).