Validity of prepartum changes in vaginal and rectal temperature to predict calving in dairy cows.

The prevalence of dystocia is high in many dairy herds. This is associated with stillbirth and negative effects to the cow. An accurate predictor of calving would enable supervision of cows more precisely to a relevant time interval so that obstetrical assistance can be provided in a timely manner. This might help to decrease calf mortality rate. Also, more accurate prediction of calving has many other advantages. Is it possible? The study by Dr O Burfeind and co-workers explored the possibility. The title of the paper published in the Journal of Dairy Science, Volume 94 of 2011, pages 5053 to 5061, is: Validity of prepartum changes in vaginal and rectal temperature to predict calving in dairy cows.

Evidence indicates that cows exhibit a decrease in body temperature before the onset of calving. The nature of this decrease in body temperature as a test to predict the onset of calving in dairy cows has not been investigated. Therefore, the objective was to investigate test criteria of a decrease in vaginal and rectal temperature as predictors of calving in dairy cows.

In three experiments, temperature loggers were inserted into the vaginas of 85 cows before calving and rectal temperatures were measured twice daily in 55 of these cows. Vaginal temperatures were respectively 0.2 to 0.3°C and 0.6 to 0.7°C lower on the day of calving compared with 24 and 48 hours before calving, whereas rectal temperatures were 0.3 to 0.5°C and 0.4 to 0.6°C lower. Vaginal temperatures exhibited a diurnal rhythm during the 120 hours before calving, which continued at a lower level during the 48 hours preceding birth. In the three experiments, a decrease in vaginal temperature of equal or more than 0.3°C over 24 hours could predict calving within 24 hours, with a sensitivity ranging from 62 to 71% and specificity (“accuracy”) ranging from 81 to 87%. Similarly, a decrease in rectal temperature measured at 07:30 of equal or more than 0.3°C could predict calving within 24 hours, with sensitivity from 44 to 69% and specificity from 86 to 88%. However, although the dairy cows exhibit a distinctive decrease in vaginal and rectal temperatures commencing approximately 48 hours before calving, detecting this decrease did not determine the onset of calving precisely. Nevertheless, in addition to the traditional signs (i.e., relaxation of the sacro-sciatic ligament), it can provide valuable information that calving is imminent.