169 PREDICTION OF THE OPTIMAL DAY OF MATING IN THE BITCH USING A BOVINE PLASMA PROGESTERONE ELISA KIT

Abstract

The present study was conducted to predict the optimal day of mating by measurement of progesterone concentration in peripheral blood of bitches using a bovine plasma progesterone ELISA kit (enzyme-immunoassay practice P kit; Kawasaki Mitaka K.K., Mitaka-shi, Tokyo, Japan). In the first experiment, blood samples were collected from 20 mature beagle bitches once a day from 1 to 13 days after the onset of proestrus (Day = 0). All bitches were mated with male beagle dogs twice on Day 9 and Day 12 after the onset of proestrus and then allowed to undergo parturition. In the second experiment, blood samples were collected from 16 mature and 7 prepubertal beagle bitches; the blood collections were randomly started between Day 4 and Day 6 and performed three times after the initiation of blood collection (the first, third, and fourth days). The bitches with progesterone concentration of <10 ng mL^-1 at the end of progesterone analysis were mated with male beagle dogs twice at 3-day intervals between Day 9 and Day 15 according to the hormonal profile. Data were compared by chi-square analysis. In the first experiment, a total of 20 bitches were mated with male dogs irrespective of hormonal profiles, of which 17 bitches became pregnant and delivered offspring. Two of the non-pregnant bitches did not show an increase of progesterone concentration during the progesterone analysis period, and the other one showed a high progesterone concentration (>10 ng mL^-1) before the mating. In the second experiment, 6 of 23 bitches were excluded from the mating with male dogs because their progesterone concentrations had reached >10 ng mL^-1 by the second day of progesterone analysis. The percentage of prepubertal bitches with high progesterone concentration before the mating (4/7, 57%) was significantly higher (P < 0.05) than that of mature bitches (2/16, 13%). A total of 17 bitches were mated with male dogs, of which 15 bitches became pregnant and delivered offspring. These results indicate that the bovine plasma progesterone ELISA kit is useful for the prediction of the optimal day of mating with male dogs, and progesterone analysis may be effective for exclusion of bitches that have ovulated before mating.