Vaginal temperature and eating, drinking, standing and walking activity rhythms of four anestrous Finnish-Landrace ewes

Four anestrous Finnish-Landrace ewes, 2–5 yr old, were maintained in separate rooms and given feed and water ad libitum. Room temperature was maintained at 17 ± 1 °C and incandescent light provided at about 100 lx from 0600 to 1800 h and total darkness from 1800 to 0600 h. A computer-controlled data acquisition system was used to record vaginal temperature, walking activity and duration of eating, drinking and standing at 15-min intervals for 29 days. Periodograms of detrended vaginal temperature data revealed strong 24-h rhythms in three of four animals. External acrophases ranged from −1.5 to −11.0 h and the amplitudes ranged from 0.03 to 0.11 °C. Peak eating, drinking, standing and walking activity tended to occur about the time of change from light to dark with some secondary peaks during the first hour of the light period. An analysis of variance indicated strong 24-h periodicities for all variables in all four animals. Least squares analysis revealed significant (P