Thermoregulatory capacity of Santa Inês hair ewes of different genotypes associated with coat colors raised in a hot environment

ABSTRACT

The relationship between hair color characteristics and thermoregulatory responses in ewes raised in hot environment were evaluated. 15 Santa Inês hair ewes of different genotypes associated with coat colors (light brown, dark brown and black) with body weight of 41.2 ± 8.1 kg were evaluated during three consecutive days. Rectal temperature (R_T, °C) and coat surface temperature (C_ST, °C) of seven anatomical points (front, back, croup, loin, side, thigh, and belly) were measured during the morning and afternoon periods. Thermoregulatory responses were recorded along with meteorological variables. Heat tolerance index (H_TI) and thermal gradient (T_G, °C) were estimated for each genotype. R_T and C_ST were influenced by periods of the day (P < 0.05), being higher in the afternoon, but T_G did not differ (P > 0.05) between periods. H_TI, C_ST, and T_G were equal (P > 0.05) among the three genotypes. Only R_T was higher in animals with dark brown coats compared to light brown, but equal to the black coat. It was observed that animals with black or dark brown hairs have a strong association between the C_ST under study, and yet these had an inverse behavior with the R_T. Animals with a darker coat tend to trigger heat dissipation in various anatomical regions of the body, presenting dynamics in thermoregulatory responses in relation to those with lighter coats. Santa Inês ewes have heat dissipation mechanisms as a function of different genotypes associated with coat colors, but have the same thermoregulatory aspects to maintain homeostasis, demonstrating an excellent adaptive mechanism in a hot environment.

KEYWORDS:

• Adaptation
• genetic resources
• homeostasis
• hair sheep
• multivariate analysis
• semi-arid region

Search regulation

All procedures performed in this study followed ethical principles of the Declaration of Helsinki.

Authorship statement

A. M. de Vasconcelos: Conceptualization, Project administration, Methodology, Supervision, and Validation

F. R. G. Lima: Supervision

M. S. M. Castro; V. O dos Santos, A. K. C. Lopes, M. R. S. de Farias: Data collect and Writing – original draft.

J. Ferreira: Writing – Review & editing

M. C. P Rogério: Supervision

R. M. F. Silveira: Conceptualization, Methodology, Data analysis, Writing – review & editing, and Validation