Body temperature, heart rate, and locomotor activity measured by bio-loggers before and after a progestogen+eCG treatment for artificial insemination in sheep: effect of pregnancy

Abstract

Context The introduction of bio-sensors for monitoring real-time changes in physiological variables has helped understand how external factors affect an animal’s resiliency to stressors. Aims To quantify changes in temperature, heart rate, and locomotor activity in ewes during hormonal treatments for artificial insemination (AI) for up to 15 days after insemination. Method Twelve ewes received a surgically implanted subcutaneous bio-logger to record data every 5 min. One week later, ewes received an intravaginal sponge for 12 days and AI was performed 54 ± 1 h after sponge withdrawal. The data were divided into the following four periods: ‘sponge in’ (Days −14 to −2), ‘day before AI’ (Day −1), ‘day AI’ (Day 0), and ‘post-AI’ (Days 1–5, Days 6–10, and Days 11–15). Key results Ewes presented significantly (P < 0.001) higher mean temperature and activity, and a lower heart rate when the sponges were in place than they did in the days following AI. Mean body temperature in the ‘sponge in’ period and the ‘day before AI’, but not in ‘post-AI period’, differed significantly (P < 0.001) between pregnant and non-pregnant ewes. Non-pregnant ewes had a significantly (P < 0.001) higher heart rate than did pregnant ewes when sponges were in and in the ‘post-AI’ period. Non-pregnant ewes were significantly (P < 0.001) less active than were pregnant ewes in the ‘sponge in’ period and on Days 1–5 after AI; however, the former were significantly (P < 0.001) more active than were pregnant ewes on Days 11–15 after AI. Conclusions The subcutaneous bio-logger system documented 24-h variations in body temperature, heart rate, and locomotor activity before and after AI in ewes that had received an estrus-synchronising hormonal treatment. Pregnancy status affected those variables and their circadian fluctuations at the time of the hormonal treatment and in the ‘post-AI’ period. Implications Any device designed for use in the study of Precision Livestock Farming that allows a simple, non-invasive measurement of these variables might provide the basis for the development of a system that could identify females that are in an optimal state for insemination, and provide an early pregnancy prediction system.