The objective of this study is to evaluate physiological parameters and the adaptability of Santa Inês sheep to two climatic conditions 25ºC (within the thermal comfort zone [TCZ) and 32ºC (above the TCZ) and three salinity levels (2.0, 4.0, and 8.0 dS m -1 ). The study was developed in a climatic chamber using 36 uncastrated male sheep. The experimental design was completely randomized with a 2 ´ 3 factorial scheme composed of two temperatures, three water salinity levels, and six repetitions. The physiological variables were not affected by the salinity levels. The rectal and skin temperature and the heart and respiratory rate were higher at 32 °C. However, the rectal temperature was within the normal range for the species. The consumption of water with different salt concentrations did not affect the adaptive responses of the animals and could be an alternative water source for sheep in regions where water has a high salinity level. The respiratory rate of sheep exposed to 32 °C increased to eliminate body heat, and exposure to 25 °C provided greater thermal comfort for the animals.

Objetivou-se avaliar as respostas produtivas de 30 ovinos mestiços ½Santa Inês + ½Dorper, com idade média de quatro meses, 15 com pelame preto e 15 com pelame branco, submetidos a estresse térmico. Os animais sofreram exposição à radiação solar direta durante uma hora (14h00 – 15h00) por semana durante oito semanas. Foram feitas as medições de altura do dorso, altura da garupa, largura do tórax, largura da garupa, perímetro do tórax, perímetro da coxa, perímetro da garupa e perímetro escrotal. Os animais foram abatidos e houve a pesagem dos seguintes componentes: sangue, pele, fígado, coração, rins, cabeça, patas, pulmão, trato gastrointestinal e vazio, testículos e pênis/uretra. Foram avaliados os pesos de carcaça quente e carcaça fria e calculadas as perdas por resfriamento e rendimento de carcaça quente e carcaça fria, além dos cortes comerciais: paleta, perna, pescoço, lombo e costela. Também foram avaliados o acabamento e conformação da carcaça e avaliação da cor, marmoreio, textura e espessura de gordura subcutânea. Os ovinos pretos apresentaram maior peso de rins e menor peso de testículos, carcaça quente, paleta, perna, costela e menor medida de largura da garupa em relação aos animais de pelame branco. O estresse térmico pode provocar distúrbios no metabolismo dos ovinos, afetando sua condição corporal e alterando seu desenvolvimento.

This study aimed to evaluate and compare the physiological variables of three sheep genotypes: Morada Nova, Somalis, and Dorper x Somalis crossbreed regarding the environment and diet in the Brazilian semi-arid region by using 30 animals (10 from each genetic group). Five of these animals had 30% of the tifton hay replaced by hairy woodrose hay. The temperature and relative air humidity were registered, the black globe temperature and humidity index (BGHI) was calculated, and the rectal temperature (RT), respiratory rate (RR), heart rate (HR), and surface temperature (ST) were measured in the morning and afternoon. The experimental design was a completely randomized design in a 3 × 2 × 2 factorial scheme, which consisted of three genotypes, two diets, and two periods, and five replications each. BGHI presented values of 81 in the shade and 90 in the sun and a significant difference (P < 0.05) was observed for the studied variables in relation to the periods, with higher values in the afternoon. The average ST was 35.48 °C in the morning and 38.11 °C in the afternoon. Morada Nova presented the lowest RT and RR (P < 0.05) among the genetic groups, with a higher tolerance to heat. The 30% substitution of tifton hay by hairy woodrose hay did not negatively affect the thermoregulatory capacity of sheep. The studied genetic groups were adapted and tolerant to climate conditions of the Brazilian semi-arid region.

The consumption of saline water in semiarid regions is a recurrent situation that can affect the ingestive behavior of small ruminants. This study evaluated the ingestive behavior of Santa Inês sheep maintained in a climatic chamber under two air temperatures-25 °C within the thermal comfort zone (TCZ) and 32 °C above the TCZ-and consuming water with three levels of salinity-2.0, 4.0, and 8.0 dS m-1. The experimental design was completely randomized in 2 × 3 factorial schemes, comprising two air temperatures and drinking water with three levels of salinity, in six replicates (animals). Regardless of air temperature, the consumption of saline water did not affect feed and water intake by the sheep; however, there was a decrease in feed intake and an increase in water intake as air temperature increased. Feed and water intake; feeding, rumination, and idle times; defecation frequency; and fecal production were not affected (P > 0.05) by the water salinity levels, whereas reduction in feed intake, feeding time, and rumination time and an increase in water intake and idle time were observed as air temperature increased. In summary, increasing air temperature negatively affected the ingestive behavior of the animals; however, water with salinity up to 8.0 dS m-1 did not affect their ingestive behavior and hence could be used for drinking.

O estresse calórico é constante em sistemas de produção, a zona de conforto térmico das diferentes espécies varia conforme a idade e o estado fisiológico dos animais. As alterações fisiológicas e comportamentais dos animais frente a modificações de temperaturas estão relacionadas com respostas provocadas pelo sistema neuroendócrino. Com a finalidade de suprir informações sobre a melhoria do ambiente térmico, estresse calórico em ruminantes, suas repostas fisiológicas e as estratégias para amenizar os efeitos foi realizada essa revisão. Diante essas informações verifica-se a importância do conforto animal para que os mesmos possam expressar o máximo de seu potencial produtivo.