Implications of Changes in Core Body Temperature

Dairy farmers and veterinarians have used body temperatures, most commonly rectal temperatures, to detect and manage febrile disease and changes in the state of cows (estrus and onset of calving) for many years. Mastitis, pneumonia, metritis, lameness, estrus, onset of parturition, heat stress, and subacute ruminal acidosis (SARA) are among the physiological conditions potentially correlated with body temperature that deviates from normal. Many new technologies have been introduced to measure body temperature of cattle at various locations, including rectum, ear (tympanic), vagina, reticulum-rumen, skin, and milk. While each location has its own advantages and disadvantages, temperature measurements at some of these locations can be automated for routine, frequent, and non-disruptive temperature recording. Systems for measurement of reticular temperature are available commercially. However, many factors other than the physiological conditions of interest affect reticular temperature. Among these are ambient temperature, food and water consumption, stage of lactation cycle, age, recumbency, activity level, stage of gestation, and of course, general health. The relationship between reticular and rectal temperatures appears to be relatively consistent, though the correlation is affected by time of season, housing system, and time of day. Reticular temperatures are affected by water intake, and substantially so for large volumes and extremely cold water; and dips in reticular temperature following water consumption must be considered when interpreting observations. Research is continuing to assess the ability of reticular temperature monitoring, perhaps in conjunction with other precision dairy farming tools, to allow earlier intervention with appropriate management. Success of early intervention will be the key to the ultimate success of any temperature monitoring technology.