The present study was conducted to clarify the possibility of synchronization of ovulation by PMSG-hCG injection in the prepuberal gilts. Seventy nine gilts were injected intramuscularly 1, 000IU of PMSG. Thirty four of them were injected intramuscularly 3ml of physiological sodium chloride solution 72 hours after PMSG injection (PMSG group). The other fourty five gilts were injected intramuscularly 500IU of hCG 72 hours after PMSG injection (PMSG-hCG group). Each of 3 to 10 of the treated gilts was laparotomied on 0, 1, 2, 3, 4 or 5 days after physiological sodium chloride solution or hCG injection (day 0=day of physiological sodium chloride solution or hCG injection) and examined the ovulation. In PMSG group, the percentage of the ovulated gilts was 0% on day 0 and day 1, and 60.0% on day 2, 83.3% on day 3, 100% on day 4 and day 5. In PMSG-hCG group, the percentage of the ovulated gilts was 0% on day 0 and day 1, and 100% on day 2 to day 5. The ovulation rates on day 2 were 85.6% in PMSG group and 94.5% in PMSG-hCG group. The ovulation rates were more than 90% on day 3, day 4 and day 5 in both groups. The number of ovulated follicles was almost the same on day 2 in both groups and was smaller in PMSG group than in PMSG-hCG group on day 3, day 4 and day 5.
From the results of the present study, PMSG-hCG injection was more effective in the induction of ovulation than single PMSG injection. Also, the present study suggests that the ovulation occurs on day 2 after hCG injection.

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The present study was conducted to clarify the changes of sex steroids and Prostaglandins around induced ovulation in the prepubertal gilts.
Forty eight prepubertal gilts were injected intramuscularly with hCG (6IU/kg of body weight; kg.b.w.) 72 hours after receiving PMSG (12IU/kg.b.w.). Ovulation was verified by laparotomy. Changes in concentrations of steroids and Prostaglandins in peripheralblood plasma, ovarian vein blood plasma and follicular fluid were examined.
Ovulation rate was 0% until 24 hours after hCG injection and 16%, 60%, 80%, 86%, 85% at 32, 36, 42, 48, 72 hours after hCG injection, respectively. And it is suggested that ovulation occurred 32 to 48 hours after hCG injection. Regarding the levels of sex steroids in the pheripheral blood plasma, ovarian vein blood plasma and follicular fluid, estradiol-17β and testosterone levels decreased as the time of ovulation approached. Progesterone levels increased markedly after ovulation. PGF_2α levels in the ovarian vein blood plasma increased near the time of ovulation. Furthermore, the levels of PGE₁, PGF_2α and 6-keto-PGF_1α in the follicular fluid also increased rapidly near the time of ovulation.
Based on these results, it is suggested that PGs are produced in the ovaries as the time of ovulation approaches and that PGs have some roles on ovulation.

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The possibility of identification of meat species by HPLC patterns of sarcoplasmic protein was investigated. In this study, sarcoplasmic proteins extracted from M. longissimus thoracis of cattle, horse, pig, goat and sheep which were treated with acetone cooled below -10°C (acetone-dried muscle powder) in order to eliminate the muscle lipid were analyzed by reverse-phase HPLC. The HPLC patterns of the sarcoplasmic protein obtained were then statistically analyzed by discriminant analysis.
The reliability of RRt was improved significantly by using sarcoplasmic proteins extracted from acetone-dried muscle powder. There was a tendency that peak area of the protein fractions was different between individuals in a species.
The chromatograms of the sarcoplasmic proteins from cattle, horse, pig, goat and sheep revealed the patterns specific to the species, respectively, and suggested that the five species can be distinguished one from another.
Results of discriminant analysis showed that the classification rule identified 12 in 13 samples for cattle (92.3%), 16 in 17 samples for horse (94.1%), 25 in 25 samples for pig (100%), 8 in 9 samples for goat (88.9%), and 10 in 10 samples for sheep (100%).

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This experiment was carried out to clarify the proliferation of the peripheral blood lymphocyte during the perinatal period in sow. The proliferative responses of peripheral blood mononuclear cells stimulated in vitro with non-specific mitogens such as pokeweed mitogen, concanavalin A and phytohemagglutinin were measured during perinatal period in nine specific-pathogen free sows. The incorporation of ³H-thymidine into the lymphocyte induced by the mitogens at 2 and 0d before parturition and at 14d after parturition was significantly lower than that at 14d before parturition. This indicates a suppression of lymphocyte proliferative response related to the parturition in the sow.

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