Plasma progesterone levels and clinical findings in dairy cows with post-partum anoestrus

In the study, 1118 Polish Black and White cows from a dairy herd were examined during a three-year period. Three hundred and eighty-eight (34.7%) animals showed no visible oestrus signs until day 60 post-partum. In those cows clinical examinations were performed twice, with a 10 day interval, and blood samples for progesterone analysis were collected simultaneously. Progesterone was measured bythe radioimmunoassay (RIA). Based on progesterone values and clinical examination silent heat was diagnosed in 189 (48.7%), ovarian afunction in 178 (45.9%), follicular ovarian cysts in 19 (4.9%) and corpus luteum pseudograviditatis in 2 (0.5%) anoestrous cows. Progesterone analysis showed that only 270 (69.6%) anoestrous cows were correctly diagnosed by rectal palpation. The results show that post-partum anoestrus is still of great importance in Polish dairy cows. The two main clinical causes of anoestrus are silent heat and ovarian afunction. Progesterone determination in milk or blood is necessary if incidences of misdiagnosis are to be avoided.