Changes in reticulorumen content temperature and pH according to time of day and yearly seasons.

The monitoring of rumen content temperature can be useful for the evaluation of cow health condition and heat. The aim of this research was to evaluate the influence of the circadian rhythm (time of day) and season on reticulorumen acidity (pH) and temperatures (RT) in lactating dairy cows. The research was performed on ten 2nd - lactation, clinically healthy Lithuanian Black and White fresh dairy cows (up to 1 day after calving). The cows were milked twice daily at 05:00 and 17:00. The cows were kept in a loose housing system, and were fed a feed ration throughout the year at the same time, balanced according to their physiological needs. Cow feeding took place every day at 06:00 and 18:00. The pH and temperature of the contents of cow reticulorumens were measured using specific smaXtec boluses manufactured for animal care. The temperature starts rising 6 hours after the evening feeding and milking, whereas 1 hour after the morning milking, it starts decreasing. The lowest temperature observed in the springtime was 38.81±0.001, and the highest was in autumn 39.17±0.001. The pH starts decreasing 3 hours after the morning feed, whereas 4 hours after the evening feed, it starts increasing. The lowest pH was observed in the summertime - 5.99±0.001, and the highest was in autumn and springtime - 6.18±0.001. In conclusion the reticulorumen temperature in lactating cows was found to be influenced by the circadian rhythm and season. The acidity of the reticulorumen content changes similar to the temperature. The pH of the reticulorumen contents was also found to be influenced by the circadian rhythm and season.