Morphophysiological profiles associated with thermoregulation in dark-coated North Tinerfeña goats and Canária de Pelo sheep in the Canary Islands

Abstract

This study evaluated and compared morphophysiological characteristics associated with thermoregulation in North Tinerfeña goats and Canária sheep, both dark-coated and maintained under similar environmental conditions on the island of Tenerife, Spain. A total of 23 adult Canária de Pelo ewes (clinically healthy, multiparous, non-pregnant; mean age 2.5 years; average body weight 39.50 ± 1.25 kg) and 30 North Tinerfeña goats (all females, aged 2–4 years and non-pregnant; average body weight 39.45 ± 3.58 kg) were evaluated. Physiological variables (rectal temperature and respiratory rate), coat morphological traits (coat thickness, hair length, and hair diameter), and environmental variables (air temperature and relative humidity) were measured. Repeated-measures analysis revealed significant population effects for rectal temperature and respiratory rate (P < 0.001). Canária sheep exhibited higher rectal temperatures and markedly higher respiratory rates than North Tinerfeña goats, although rectal temperature remained within the physiological range of homeothermy in both populations. North Tinerfeña goats exhibited significantly thicker and longer coats with larger hair diameters than Canária sheep (P < 0.001), demonstrating marked population-associated differences in coat morphology. Canonical discriminant analysis performed at the individual-animal level and validated using leave-one-animal-out cross-validation correctly classified 98.1% of animals using physiological traits alone and 100% using either coat morphological traits or the combined set of physiological and morphological variables. The classification tree identified hair length as the primary discriminatory trait between populations, with a threshold of 54.70 mm completely separating the two groups within the evaluated population. These findings demonstrate pronounced population-associated physiological and morphological differentiation related to thermoregulation in dark-coated North Tinerfeña goats and Canária sheep and provide a basis for further investigation of thermoregulatory variation in locally adapted small ruminants.