[Estrogen determination in the urine of heifers during natural and CAP-affected sexual cycle]

With all differences due to environmental effects and individuality, oestrogen secretion actually follows a typical line of dynamics during one normal sexual cycle. Oestrogen curves were found to rise on the seventh and ninth days of the sexual cycle and to reach a maximum level on the last day. Cycle-depending differences between oestrogen concentrations were found to be leveled on the eighth day, when the oestrus had been synchronised by means of CAP. Oestrogens then went down, in response to synchronisation, up to the 15th day. Both the curve proper and the amount of oestrogens in the given cycle, following synchronised oestrus in heifer, practically were congruent with the values recordable from a normal sexual cycle. Two daily CAP doses of 10 mg per individual did synchronise oestrus in heifer and had no side effects on ovarian function over the following sexual cycle.