Accuracy of Ultrasonography and Rectal Palpation in the Diagnosis of Silent Heat in Cows Compared to Plasma Progesterone Concentration

The study was carried out on five dairy herds in the North-East Poland. The cows, which showed no visible oestrus signs until day 60 postpartum, were examined by ultrasonography and rectal palpation twice, at a 10-d interval. A real-time, B-mode scanner with a 5 MHz probe was used. The plasma progesterone concentration was determined using RIA. A high progesterone level on the first examination, but low on the second, or low on the first and high on the second examination were interpreted as a silent heat. Based on the progesterone values, silent heat was diagnosed in 145 anoestrous cows, whereas ultrasonographically, 106 cows were found to have silent heat. The accuracy of the ultrasonography and rectal palpation in the diagnosis of silent heat in cows was 89.0% and 69.7%, respectively (P≤ 0.05). For the diagnosis of the corpus luteum, the sensitivity and specificity of the ultrasonography was 94.7% and 84.0%, and for rectal palpation 86.2% and 70.3%, respectively (P≤0.05). Our results showed that ultrasonography is a useful tool in the diagnosis of silent heat in cows.