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

Author(s)

Carvalho Fonseca, Vinicius de Franca ^{[1, 2]} ; Campos Maia, Alex Sandro ^[1] ; Saraiva, Edilson Paes ^[3] ; de Melo Costa, Cintia Carol ^[1] ; da Silva, Roberto Gomes ^[1] ; Abdoun, Khalid Ahmed ^[4] ; Al-Haidary, Ahmed Abrahim ^[4] ; Samara, Emad Mohammed ^[4] ; Fuller, Andrea ^[2]

Affiliation

^[1] Sao Paulo State Univ, Biometorol Lab, Innovat Grp Biometeorol Behav & Anim Welf INOBIO, Jaboticabal - Brazil

^[2] Univ Witwatersrand, Sch Physiol, Brain Funct Res Grp, Johannesburg - South Africa

^[3] Univ Fed Paraiba, Anim Biometeorol & Ethol Grp BIOET, Areia - Brazil

^[4] King Saud Univ, Dept Anim Prod, Riyadh - Saudi Arabia

• Document type: Journal article
• Source: Journal of Thermal Biology; v. 84, p. 83-91, AUG 2019.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 11/17388-6 - Effects of solar radiation and air temperature on methane emission as associated with metabolic heat production and latent heat loss in ruminants
• Grantee: Alex Sandro Campos Maia
• Support Opportunities: Regular Research Grants