Agreement between ultrasonographic classification of the CL and plasma progesterone concentration in dairy cows.

摘要

The study was conducted in 2 phases. In the first phase, the ovaries of 8 cows were examined ultrasonographically and plasma progesterone was assayed daily from oestrus (day 0) to day 4, then on days 7 and 10 and daily from day 17 to the onset of the next oestrus. The corpora lutea (CLs) were classified on the basis of echogenic characters as follows: absence of CL, evolving CL, mid-cycle CL. On the basis of the progesterone values, the CLs were classified as (1) non-secretory CL when plasma progesterone was <1 ng/ml; (2) evolving CL when progesterone was between 1 and 4 ng/ml; (3) mid-cycle CL when progesterone was >4 ng/ml. In the second phase, the ovaries of 157 randomly selected Friesian cows were examined once by ultrasonography, and blood samples were collected concurrently and analysed for progesterone content. The degree of agreement between the CL classification by ultrasonography and by progesterone concentration was 72%. Ultrasonographic characters of day 3-4 CLs and their respective plasma progesterone concentrations were not distinguishable from those of CLs 3-4 days before the next oestrus.