Does the metabolic and behavior daily variation pattern on rams differ in summer and winter?

ABSTRACT This study aimed to compare the daily variation pattern of testosterone, cortisol, insulin, total blood protein, albumin concentration, glycemia, activity pattern, and surface temperature in 10 Corriedale rams during the breeding (BS) and the non-breeding (NBS) seasons. The surface temperature had a greater mesor but a lower amplitude (P < 0.001), and its’ acrophase was later during the BS than during the NBS. The mesor and amplitude of cortisol were lower during the BS than during the NBS (P = 0.01 for both). The acrophase of the time sleeping and the glycemia:insulin ratio occurred earlier during the BS than during the NBS (P = 0.001 in both). During the BS, there was a greater mesor of testosterone, a greater glycemia (P < 0.001), and a tendency to greater insulin (P = 0.06) than during NBS, but without changes in their daily variation pattern between seasons. In conclusion, some daily variation patterns were robust and maintained despite seasonal variations. Other patterns such as the surface temperature, the behavior pattern, cortisol concentration, and glycemia:insulin ratio were more sensitive to the modulation exerted by environmental variations or the internal changes triggered by them, probably because they are directly involved in favoring the seasonal adaptation in rams.