DETECTION OF SILENT ESTRUS IN DAIRY-COWS BY MILK TEMPERATURE-MEASUREMENT

Milk temperature was measured automatically during milking with a view to detecting silent oestrus in dairy cows. A total of 38 silent oestr ous periods were studied, based mainly on ovulation and milk progester one levels together with visual observation. In 78.9% of silent oestro us periods, a significant increase in milk temperature amounting to a mean of 0.6 (s.e. 0.07)degrees C was found, and this was highly correl ated (r = 0.90) with an ir increased body temperature. In most silent oestrous periods increases in milk and body temperatures and ovulation with milk progesterone levels below 2 mu g/l were found, the oestrous cycles being characterized by typical progesterone profiles. In some cows increases in milk and body temperatures and ovulation during a si lent oestrous period were associated with non-typical progesterone pro files although most of these occurred shortly after parturition.