The aim of this study was to assess the estimates of the time of ovulation and mating derived by plasma progesterone concentration. The 40 mature Korea Jin-do bitches were monitored to determine the plasma progesterone concentrations from proestrus to parturition.
Gestation length in the 30 pregnant bitches was 63.9±2.3 (mean±SD) days in multiparous bitches and 61.8±3.6 days in primiparous bitches when Day 0 was timed from the first day of male acceptance, and 61.4±1.8 days and 61.3±2.7 days when Day 0 was timed from the day of first mating, respectively. Also, gestation length was 63.1±1.4 days, 62.4±1.1 days and 61.5±0.9 days in multiparous bitches, and 62.6±1.4 days, 62.4±2.0 days and 61.6±2.3 days in primiparous bitches when Day 0 was timed from the day that plasma progesterone concentration was first increased above 2.0, 3.0 and 4.0ng/㎖, respectively, and 53.8±3.1 days and 54.8±2.6 days when Day 0 was timed from the last day of male acceptance, respectively.
In 30 pregnant bitches, plasma progesterone concentration was 0.2±0.2ng/㎖ in multiparous bitches and 0.7±0.8ng/㎖ in primiparous bitches at the first day of vulval bleeding, 1,9±1.0 and 3.3±2.7ng/㎖ at the first day of male acceptance, 7.0±4.0 and 9.3±6.2ng/㎖ at the day of first mating, and 25.1±6.3 and 22.8±10.3ng/㎖ at the last day of male acceptance, respectively.
When Day 0 was timed from the day of parturition, plasma progesterone concentration at Day-62, Day -63 and Day -64 was 4.7±2.7ng/㎖, 3.5±2.2ng/㎖ and 1.7±0.9ng/㎖ in multiparous bitches, and 5.3±4.4ng/㎖, 3.2±3.7ng/㎖ and 2.0±1.9ng/㎖ in primiparous bitches, respectively.
When Day 0 was timed from the day that plasma progesterone concentration was first increased above 3.0ng/㎖ after the first day of vulval bleeding, plasma progesterone concentration at Day 61 and Day 62 was 2.7±2.2ng/㎖ and 1.4±1.9ng/㎖ in multiparous bitches, and 3.4±5.2ng/㎖ and 3.7±5.6ng/㎖ in primiparous bitches, and 0.8±0.7ng/㎖ and 0.9±0.4ng/㎖ at Day 63, respectively.
It was that bitches were mated when plasma progesterone concentraion was 1.9 to 14.2ng/㎖ and 3.5 to 20.0ng/㎖ in multiparous and primiparous bitches, which was between first day before ovulation and fourth day after ovulation. And pregnancy rate was 92% (23/25).
From these data, ovulation was estimated to occur the day when plasma progesterone concentration was first increased above 3.0ng/㎖ after the first day of vulval bleeding. It was estimated that mating time was the day when plasma progesterone concentration was between 1.9 and 20.0ng/㎖, and best time for mating was between 3.0 and 8.0ng/㎖ of plasma progesterone concentration.
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