Abstract: Forty-five dairy cows were used to compare the
enzyme activity of alkaline phosphatase (ALP), lactate
dehydrogenase (LDH), α -amylase in the cervical mucus of cows
during spontaneous and induced estrus using progestagen or PGF2 α
and to determine whether these enzymes affect the fertility in cows
with induced estrus, at the time of Al. The animals were assigned to 3
groups (no treatment, a Crestar® for 12 days, a double im injection of
PGF2 α). The cows were artificially inseminated (AI). Cervical
mucus samples were collected from all cows 3 to 5 min before the
AI. The results are summarized as follows: ALP and α -amylase
activity for spontaneous estrus were similar to those for induced
estrus (P>0.05) . LDH activity levels during spontaneous and PGF2 α
induced estrus was significantly lower (P < 0.001) than that in
progestagene induced estrus groups. While no difference was found
between the first and the third groups. Our result showed a significant
difference in LDH activity levels between cows conceived with 2 or
more AI and those conceived with 1 AI. The result of this study
showed that the enzyme activity in cervical mucus is helpful for
detection of ovulation and time of AI.