Daily rhythms of body temperature around lambing in sheep measured non-invasively
Fifteen ewes had data-loggers affixed under the tail, programmed to record temperature (T) every 5 min, storing up to 72 h of data. Ewes were monitored to identify time of lambing (time 0). Lambing period lasted 5 d; thereafter seven ewes which yielded data for 24 h before and after lambing were selected. Mean T (±S.E.M.) was 39.03±0.02°C. Mean T in the 24 h preceding lambing (38.68±0.02°C) was lower than it was in the 24 h following parturition (39.38±0.03°C) (P< 0.0001). T was lower in the 12 h preceding lamb birth (38.56±0.10°C) than it was in the previous 12 h (−24 to −12, 38.76±0.02°C) (P<0.0001); thereafter, T was lowest precisely at parturition (mean T = 38.18±0.03°C) and increases rapidly and peaked (mean T = 39.70±0.04°C) 2 h after lambing. In the 12 h following delivery (39.28±0.02°C), T increased, especially in the window +12 to +24 h (39.51±0.03°C). In conclusion, T of ewes changed around parturition, with a reduction 12 h before lambing, followed by a rapid increase in the hours following parturition. The data-loggers used proved a high degree of sensitivity to detect physiological T changes, which confirmed that they are appropriate for use in sheep studies.