Abstract
The aim in this study was to obtain the basic data for estimation of optimal mating time and ovulation time by finding out the relationship between vaginal cytology and reproductive hormone profiles during the estrous cycle in 36 Korea Jin-do bitches. A characteristic features of vaginal cytology during the estorous cycle were the high proportion of superficial cell, anuclear cell and erythrocyte in proestrus, superficial cell, anuclear cell and erythroucyte in estrus, parabasal cell, small and large intermediate cell and leukocytes in diestrus, and parabasal cell and small intermediate cell in anestrus, respectively. Cornification index(CI) was the high proportion in proestrus and estrus, then it was decreaed in diestrus and anestrus. It indicated that the CI was significantly high proportion in proestrus and estrus in comparison with the other phases. Plasma progesterone concentration was below 1.0ng/ml at the first day of vulval bleeding in pregnant and non-pregnat bitches, and then it was increaed slowly. When Day 0 was timed from the day that plasma progesterone concentration was first increased above 4.0ng/ml, plasma progesterone concentrations at Day 0 in pregnant and non-pregnant above 4.0 ng/ml, plasma progesterone concentrations at Day 0 in pregnant and non-pregnant bitches were $5.2{\pm}0.3ng/ml and 5.7{\pm}0.5ng/ml$$46.5{\pm}3.3 ng/ml$ in pregnant bitches and at Day 20 with $39.8{\pm}0.1ng/ml$ in nonpregnant bitches. It indicated that plasma progesterone concentration was higher in pregnant bitches than in non-pregnant bitches. Hereafter plasma progesterone concentration was decreased steadily. At Day 63 which is parturition day, plasma progesterone concentration was decreased below 1.0ng/ml with $0.8{\pm}0.2ng/ml$ in pregnant bitches whereas in the non-pregnant bitches at Day 75 were decreased below 1.0ng/ml with 40.5{\pm}0.4ng/ml$. Plasma progesterone concentrations was maintained below 1.0ng/ml during anestrus in all of them. The plasma estradiol-17 $\beta$ concentration was increased above 1.0 pg/ml at the first day of vulval bleeding and it showed a peak Day-1 with 38.2 pg/ml. Thereafter it was sharply decreased after Day 0, which was the day that plasma progesterone concentration was first increase above 4.0ng/ml, and was maintained below basal levels. In relationship between CI and reproductive hormones, plasma estradiol-17 $\beta$concentration showed a peak at Day-3 and CI showed a peak at Day-1 which was the second day after plasma estradiol-17 $\beta$ peak, and plasma progesterone concentration was first increased above 4.0ng/ml at Day 0 which was the first day after CI peak. CI was first increased above 80% at Day-6 which was the third day before plasma estradio-17 $\beta$ peak and it was maintained above 80% between Days-6 and Day 3 during 10 days, and showed above 90% at Day-3 which was the day that plasma estradiol-17 $\beta$peak and was maintained above 90% between Day-3 and Day 3 during 7 days. In conclusion, ovulation in Koran Jin-do bitches occurred at the first day after CI peak, at the third day after plasma estradiol-17 $\beta$peak and the day when plasma progesterone concentration was first increased above 4.0 ng/ml. And it was estimated that the optimal mating time was the day when the CI was maintained above 90% and plasma progesterone concentration was between 3.0~8.0ng/ml. Therefore plasma progesterone concentration measurement was used for determination of an accurate ovulation time and the optimal mating time but also vaginal cytology, which is low-priced with equipment and is the simple examination method, was reliable method for estimating estrous cycle, optimal breeding time and ovulation time in Korea Jin-do bitches.
