Diagnosis of post-partum anoestrus in dairy cattle

A study was carried out to establish the incidence of anoestrus in dairy cattle in Southern Chile. Cows that had not been seen in oestrus up to 60 days after parturition were considered in anoestrus and were clinically examined. Cows without corpora lutea were designated clinically anoestrus and a milk sample was taken for progesterone radioimmunoassay. Cows with progesterone concentration below 9.5 nmol/L were considered to be in true anoestrus. A total of 1831 post-partum cows from 10 farms were studied. Based on the reproductive records, 208 cows were in anoestrus (11.3% with a range from 4.3 to 33.3%). The clinical examination revealed that only 66 out of the 208 cows were in clinical anoestrus reducing the anoestrus percentage to 36% (range 1.9 - 10.8%). The progesterone concentration in skim milk showed that only 41 cows had low values compatible with anoestrus. Thus the true incidence of anestrus was 2.2% with a range of 0.8 to 7.0% between farms. In conclusion, the figures from the different methods of diagnosis of anoestrus (records, clinical and endocrine status) seem to be within the range of reported data in countries with high standards for livestock production. This study identified true reproductive problems, such as deficient oestrus detection and failures in clinical diagnosis of active CLs. Also, it confirmed that progesterone RIA is a valuable tool to monitor ovarian activity. (author). 18 refs, 1 tab