Bio-thermal responses and heat balance of a hair coat sheep breed raised under an equatorial semi-arid environment

• Autor(a) principal: Carvalho Fonseca, Vinicius de Franca [UNESP]
• Data de Publicação: 2019
• Outros Autores: Campos Maia, Alex Sandro [UNESP], Saraiva, Edilson Paes, Melo Costa, Cintia Carol de [UNESP], Silva, Roberto Gomes da [UNESP], Abdoun, Khalid Ahmed, Al-Haidary, Ahmed Abrahim, Samara, Emad Mohammed, Fuller, Andrea
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.jtherbio.2019.05.024; http://hdl.handle.net/11449/194844
• topic: Morada nova sheep; Body temperature; Metabolism; Nycthemeral cycle; Sensible heat loss; Adaptation

Long-term assessments of bio-thermal responses in a hair coat sheep breed were performed to investigate the effect of the thermal environment on their physiological performance and thermal balance. Twelve healthy non-lactating Morada Nova ewes (3 +/- 1.2 years old, body mass 32.7 +/- 3.7 kg) were assigned in two 12 x 12 Latin square designs (from 07:00 to 19:00 h and from 19:00 to 07:00 h, respectively) for assessments of their biothermal responses during 24 consecutive days. There was a monophasic pattern in the ambient temperature (T-A), which ranged between 21 and 38 degrees C, thereby exposing the ewes to different levels of surrounding T-A over the day and influencing several of their bio-thermal responses (P = 0.0001). Their body temperatures (i.e., rectal, skin, and hair coat surface temperatures) gradually increased (P = 0.0001) from 04:00 h. The mean peak for rectal temperature (39.3 degrees C) was recorded at 19:00 h, while for skin and hair coat surface temperatures it occurred at 13:00 and 14:00 h, respectively. The sensible heat loss by long wave radiation and surface convection exceeded the metabolism of ewes when the T-A was below 24 degrees C, which usually occurred between 24:00 and 06:00 h. During exposure to higher ambient temperatures, the sheep increased respiratory evaporative heat loss, without panting. In conclusion, the sheep regulated rectal temperature within a relatively narrow range of 1.4 degrees C over 24 h, and appear to be well adapted to coping with heat. Minimum 24 h body temperature was correlated with minimum T-A, indicating that heat conservation strategies are likely to be important for Morada Nova sheep in a tropical biotype at night, when rates of sensible heat loss exceed the heat generated by metabolism.