Are there differences in the adaptive profile of hair sheep and their crosses with wool breeds?

• Published in: International journal of biometeorology 2024-02, Vol.68 (2), p.229-236
• Main Authors: Silveira, Robson Mateus Freitas, Garcia, Paulo Rogério, de Castro Júnior, Sérgio Luís, Arno, Alessandra, da Silva, Iran José Oliveira
• Format: Article
• Language: English
• Subjects: Air temperature; Animal Physiology; Biological and Medical Physics; Biophysics; Blood; Blood levels; Body temperature; Circadian rhythms; Correlation; Dissipation; Earth and Environmental Science; Enthalpy; Environment; Environmental conditions; Environmental Health; Homeostasis; Hormones; Hot weather; Meteorology; Original Paper; Physiology; Plant Physiology; Respiration; Respiratory rate; Sheep; Surface temperature; Thermal comfort; Thermal stress; Thyroid; Thyroid gland; Thyroid hormones; Thyroxine; Time factors; Triiodothyronine; Variance analysis; Wool
• ISSN: 0020-7128; 1432-1254
• DOI: 10.1007/s00484-023-02585-2

This study aimed to evaluate and compare the physiological performance of different genetic groups of sheep, by physiological variables and serum hormone levels, in a hot weather environment. Thirty sheep from five genetic groups were used: Santa Inês (SI), ½ Dorper + ½ Santa Inês (DO), ½ Ilê de France + ½ Santa Inês (IF), ½ Suffolk + ½ Santa Inês (SK), and ½ Texel + ½ Santa Inês (TX). The readings and records of physiological parameters (respiratory rate (RR), rectal temperature (RT), auricular cavity temperature (ACT), and surface temperature (ST)) were carried out at 7:00 am, 1:00 pm, and 7:00 pm, in 12 non-consecutive days. The collections of blood samples for hormone analysis (triiodothyronine (T 3 ), thyroxine (T 4 ), and cortisol (CORT)) is in four consecutive days. The environmental conditions of the experimental period caused a thermal discomfort in the sheep, but not a state of thermal stress. The thermolysis mechanisms, sensitive (ST and ACT) and latent (RR) processes, were enough to maintain their homeostasis (RT). The results showed that crossbred breeds presented a higher metabolism and were more efficient at dissipating heat through thermolysis than the SI breed. The crossbred breeds were efficient at dissipating heat through the elevation of body surface temperature and respiratory rate, mainly SK and TX, i.e., crossbred breeds, despite the wool cover, used thermoregulatory mechanisms that promoted lower variation of RT. The analysis of variance showed significant effects ( P