A strain development with Landrace pigs was carried out from 1990 to 1996 (for five generations) to improve reproductive ability and the meat performance. The pigs were selected mainly based on EBV of litter size with the BLUP method at 90kg of live weight, and mated atapproximately eight months of age. The mathematical model to analyze the data included the effects of generation and live weight of the females at the time of first mating. The average litter size per generation increased from 9.7 to 10.8 during the experiment. The regression of the litter size was significantly (p<0.05) affected by the weight at first mating, of which the regression coefficient was 0.03 piglet per kilogram of weight. Effect of generation on litter size was not significant. The genetic gain of litter size per generation was 0.14 on the model including generations and was 0.09 on that including both generations and weight of first mating. These results indicate that selection by the BLUP method is feasible for the improvement of the litter size of swine, and that it should be more effective if the body weight at the time of first mating is considered.

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The present study was conducted to clarify the changes of sex steroids and Prostaglandins at inhibition of ovulation by an inhibitor of Prostaglandin biosynthesis in the prepubertal gilts. Thirty prepubertal gilts were injected intramuscularly with hCG (6IU/kg of body weight; kg. b. w.) 72 hours after receiving PMSG (12IU/kg. b. w.). Twentyfour hours after hCG injection, they were injected intramuscularly either phisiological saline solution (Control Group; n=15) or 7.6mg/kg. b. w of indomethacin (Indomethacin Group; n=15). In each ten gilts of both groups, the ovulation was verified by laparotomy on 2, 3 or 7 days after hCG injection, respectively. In each five gilts of both groups, blood sample was withdrawn from jugular vein until 25 days after hCG injection and levels of sex steroids were measured.
The patterns of the changes in the levels of Progesterone, Estradiol-17β and Testosterone in peripheral blood plasma and ovarian vein blood plasma were similar in Control and Indomethacin Group. In Indomethacin Group, ovarian follicular fluid was in ovarian follicle even on the 7th day after hCG injection. The concentration of progesterone in follicular fluid was very high. The concentration of PGE₁ and PGF_2α in follicular fluid did not increase and remained low level.
The patterns of the changes in the levels of Progesterone, Estradiol-17β and Testosterone in peripheral blood plasma for 25 days after hCG injection were not different in both Control and Indomethacin Group. The life span of corpus luteum was 18 days in Control and Indomethacin Group, respectively. Based on these results, it is suggested that inhibition of ovulation by indomethacin did not influence steroidogenesis in ovarian follicle. It is also suggested that prostaglandins take part in some roles in the phenomenon of rupture of follicle.

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The physicochemical properties of a red pigment in Parma ham were examined in this study and compared with those of other myoglobin (Mb) derivatives whose red color is due to oxymyoglobin (O₂Mb) and nitrosylmyoglobin (NOMb). A water extract of Parma ham was prepared and the absorption spectra of the final filtrate were recorded at 350-650nm. The effects of pH on the absorption spectra were studied subsequent to the addition of NaOH or HCl to the water extract. A single absorption peak was noted at 423nm in the Soret's band and 2 peaks at visible wavelengths of 549 and 587nm. The absorption spectra of red pigment had no change at pH 6-10. At pH 5, the red pigment started to precipitate and increasingly more so as pH became more acidic. No typical absorption peaks for metmyoglobin (MetMb) could be seen at 505 and 630nm at any pH. The sterile water extract of Parma ham was kept in a sterilized test tube for 7 days at low (5°C) or room temperature (20°C) under conditions of light exposure or darkness. The red pigment of the water extract was stable in the dark at each temperature during 7 days of storage. To the water extract of Parma ham and each of the O₂Mb and NOMb solutions, ferricyanide was added. O₂Mb and NOMb were oxidized by ferrycianide to MetMb, but the spectrum of the water extract from Parma ham had no change. The water extract of Parma ham and the O₂Mb and NOMb solutions were heated at 40-70°C for 30min followed by measurement of the absorption spectrum. The heated extract was filtered under sterile conditions. For the water extract, absorption of the spectral peaks decreased, though the spectrum of this pigment was maintained essentially during heating, in contrast to those of O₂Mb and NOMb; precipitation of the pigment was noted with increasing temperature. The pigment precipitated with foreign proteins denatured by heating, but could be detected in its acetone extract.

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Computer simulation of a closed pig strain was used to analyze effects of change in number of animals measured on genetic parameter and breeding value estimates obtained by single-trait REML with an animal model. Two different heritability levels (0.25 and 0.50) for the traits were used. In each generation, 10 boars were mated to 50 guts randomly and each mating produced 4 progenies as candidates for selection. Each animal except those in base population was assumed to have one record. Population mean only was considered as a fixed effect in the computer simulation. Additive genetic and error variances from information on 200 animals measured in the first generation were estimated not to be in agreement with actual parameters. Mean squares errors of genetic parameters decreased with increase in the number of animals measured. Mean square error of correlation between true and estimated breeding values in the last generation hardly decreased with increase in amount of information from two generations or more. It was concluded that amount of information on about 400 animals measured was sufficient for estimating genetic prameters and breeding values in the closed pig strain.

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