A new cervical mucus penetration test (CMPT) technique was developed for determination of the potential fertility of bulls in this study.

In the first stage of the experiment artificial inseminations were conducted by using the frozen semen of 10 Holstein bulls. The first and last 3 bulls whose mean non-return rates (NRR) scores had significantly difference formed the high and low fertility groups respectively, and their frozen semen were used at the 2nd stage (CMPT) of the study. Differently from the current CMPT methods the cervical mucus was drawn into transparent straws of 0.25 ml. Than incubated with thawed semen at 3 various temperature (37, 39 and 41ºC) and for 2 various periods (15 and 45 min). Following incubations, the straws were frozen at liquid nitrogen vapour and stored at -20ºC. On the examination day, the straws were cut into pieces by measuring the lengths from the open end as following; 15-15.5 mm (1st penetration interval; PA1), 32.5-35 mm (PA2) and 50-52.5 mm (PA3) 2.5 mm each. Frozen mucus portion in each cut straw part is then pushed out on slight glasses by means of a piece of wire and cover glass was placed for spermatozoon count under a phase-contrast microscope (200x).

A significant positive correlation was found between the individual NRR scores of bulls and spermatozoon numbers at PA3 (P<0.05) and motility (P<0.01), and a negative correlation between the individual NRR scores and acrosomal defect rate (P<0.01), other morphological defect rate (P<0.01) and total morphological defect rate (P<0.01). Also, in the 41ºC for 15 min incubation period, when compared with the low fertility group, bulls from the high fertility group had a higher number of spermatozoa at PA3.

We have concluded from this study that, (a) this new CMPT method can be used for determination of fertility in bulls in combination with routine spermatological tests, and that (b) the further penetration distance (PA3), the high incubation temperature (41ºC), and the short incubation period (15 min) allow yielding of clearer test results.