Concentration of plasma free fatty acids (FFAs), the decomposition products of body fats, of the six Landrace were determined by gas chromatography/mass spectrometer system (GC/MS) to examine the relationship between the body weights and the composition as well as concentration of FFAs in plasma. Blood samples were collected in the fed state at 30, 50 and 70kg, and in the fasted state at 90kg in live weight. The FFAs were assayed by firstly extracting lipids from plasma, isolating them by thin layer chromatography, converting the FFA fraction into methyl esters, infusing the methyl esters into a GC/MS and then quantifying the methyl esters by selected ion monitoring method (SIM) using methyl pentadecanoate as an internal standard. The monitored ions of 14:0, 15:0, 16:0, 16:1, 18:0, 18:1 and 18:2 were m/z=74.0, 74.0, 74.0, 236.3, 298.3, 264.3 and 294.3, respectively.
FFA sampled from plasma of the swine in fed state had higher percentage of palmitic acid (16:0) and linoleic acid (18:2), and a lower percentage of oleic acid (18:1) than the counterparts from their subcutaneous fat. Findings on the change in the composition of FFAs in plasma during growth of swine revealed that saturated FFAs increased and linoleic acid (18:2) decreased as swine grew up, as seen in the subcutaneous fat. The concentration of FFAs after the fasting amounted to approximately five times of that in fed state, and the composition of FFAs became very much similar to that of subcutaneous inner layer fat.

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In order to induce estrus and ovulation in prepuberal gilts in a simplified manner, a comparative study was conducted on varying doses of HCG with check for varying responses after the administration. The results were as described below.
1) Estrus signs were noted in all the gilts treated with HCG as time advanced.
2) A low dose (250 IU) of HCG could induce clearly notable estrus response, whereas higher doses (1500-3000 IU) resulted in poorer responses.
3) The processes of estrus response development with 250 IU of HCG were marked increase in redness of vulva at 72 hours after its administration and swelling of vulva at 72 hours to 120 hours, followed by exudation of mucus from vulva, wrinkles of vulva and response to back pressure, all clearly distinguishable, at 120-144 hours after HCG administration.
4) Of the changes in the conditions of genital organs in time lapse after HCG administration, the weights of ovary were found to have gained 5 times greater with more than 500 IU of HCG than those before its administration and the lengths and weights of uterine horns tended to increase.

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Development of reproductive organs such as ovary, uterine horn, and uterine cervix were grossly and histologically examined at varying ages of prepuberal gilts, i. e. 6 at age of 70 days (Group A), 7 at age of 130 days (Group B) and 12 at age of 180 days (Group C), twenty five in total. The following results were obtained.
1) The mean body weight of gilts in Groups A, B and C was 24.0kg, 65.7kg and 103.9kg respectively. The mean weight of the ovary was 0.68g (A), 1.73g (B) and 3.02g (C), and the mesurement of the ovary was 1.30×1.03×0.67cm, 2.01×1.40×1.10cm and 2.40×1.85×1.20cm in Group A, B, and C, respectively. The mean weight of uterine horn was 3.0g, 12.4g and 29.1g, while the mean length of the horn was 13.3cm, 25.2cm and 35.5cm in Group A, B, and C, respectively. The regression equation showed a significant correlation between the body weight and ovarian weight (r=0.89), and between the ovarian weight and cervical weight (r=0.78).
2) The ovaries of four gilts in Group A showed only primordial or primary follicles and no mature follicle was found out. Hemorrhage was noted in some follicles of two gilts in Group C.
3) Atretic follicles of the initial, middle and late stages were observed in only one gilt of Group A, and all the gilts of Groups B and C. The ratios of the number of atretic follicles to all the follicles were 58.3%, 30.5% and 45.7% for Group A, B and C, respectively. There were no significant findings in the mucosal epithelium of the horn or cervix of uteri.
4) It was thus found out that there was no rapid growth of reproductive organs at the prepuberal stage of the gilts and that gradual growth was attained in them as their body weights gained and rapid growth was attained at the puberal stage.

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