Seasonal adaptive strategies of North Tinerfeña goats in the Canary Islands, Spain.

Climate change has intensified thermal challenges in livestock production systems, reinforcing the need to understand adaptive mechanisms in locally adapted breeds. This study aimed to characterize the seasonal adaptive profile of North Tinerfeña goats, an autochthonous breed from the Canary Islands. Thirty adult non-pregnant female goats were evaluated under standardized management conditions. Repeated measurements of rectal temperature (RT), respiratory rate (RR), and coat surface temperature (CST) were obtained twice daily, in the morning and afternoon, throughout a one-year study period encompassing winter and summer. Coat characteristics (coat thickness [CT], hair length [HL], hair diameter [HD], and hair angle) were measured once per day during winter and summer. Physiological variables were significantly affected by season and period of the day (p < 0.001), with a significant season × period interaction for RR and CST (p < 0.01). Coat traits showed pronounced seasonal variation, with CT significantly greater in winter (p < 0.001) and HL significantly greater in summer (p < 0.001), whereas HD did not differ between seasons (p > 0.05). Multivariate analyses revealed distinct seasonal adaptive patterns, with CT and HL identified as the main discriminant variables between winter and summer (discriminant analysis, p < 0.001). Decision tree (CHAID) analysis identified coat thickness as the primary classifier of seasonal condition, with a threshold value of CT ≤ 8.7 mm predominantly characterizing summer (p < 0.001). These findings demonstrate that North Tinerfeña goats rely on integrated and season-dependent thermoregulatory strategies, in which morphological coat traits predominate during winter, while rapid and sensitive physiological responses are preferentially activated during summer to maintain homeothermy. This study provides novel phenotypic evidence of local adaptation and highlights the potential use of objective morphological thresholds, such as coat thickness, combined with simple physiological indicators, to support management and conservation strategies for insular goat breeds under climate change scenarios.