Infrared thermometry for detecting estrus and pregnancy in Holstein cows

Efficient reproductive management is paramount in enhancing the productivity and welfare of dairy cows. This study investigates the effects of pregnancy status, seasonal variations, and diurnal shifts on the body temperature of different body parts in dairy cows. Using a structured approach, cows were categorized based on pregnancy status (pregnant vs. control) or estrous status (estrous vs. control), season (winter, spring, summer), and time of day (morning, noon, evening). The analysis revealed that pregnancy and estrous statuses significantly affect the body temperature, with pregnant and estrous cows displaying higher temperatures (39.0 ± 0.03 and 38.0 ± 0.06 °C, respectively) than controls (37.1 ± 0.06 °C; p < 0.01). Seasonal impacts were also notable, with the highest temperatures observed in summer (38.3 ± 0.07 °C) followed by spring (38.1 ± 0.09 °C) and winter (37.7 ± 0.06 °C; p < 0.01), indicating a strong environmental influence on physiological responses. Furthermore, diurnal analysis indicated temperature fluctuations throughout the day, peaking at noon (38.1 ± 0.09 °C; p < 0.05) compared to morning and evening. High positive correlations were observed between the measured temperatures in different areas and rectal and vaginal temperatures, suggesting the skin surface is ideal for assessing thermal changes. These findings underscore the critical interplay between an animal's physiological state and external environmental factors in managing dairy cow health and reproduction. The study highlights the potential of non-invasive temperature monitoring as a tool for optimizing reproductive management and underscores the necessity of accounting for environmental and physiological variations in dairy management practices.