The most important managerial strategy for the betterment of pig farm management is to improve meat production performance of breeding pigs which is one of the basic means for production. The present study aims at obtaining useful information for efficient meat production of pigs and providing a method for improving profitability of pig farm management on the basis of the results of meat production performance tests for breeding pigs. The statistical analysis of the results was conducted in accordance with the method of multivariate analysis utilizing a large computer. The results of the study were as summarized hereunder. As to the traits such as the mean daily gain, carcass weight, length of dorsal loin and loin eye area, it was revealed that the figures of kurtosis and skewness which are the descriptive statistical values for the objective pigs were larger than those of any other traits and that the mode was leaned toward left from the mean values, showing a tapered distribution. These traits were rather inferior to those of the average values and it was found out that it would be necessary to improve the meat production performance of pigs. The discriminatory items in the overall judgement of results were not necessarily useful for classifying the characteristics of the pig progeny test results. There were some traits showing significant differences among the rating items, whereas some others showing none of the differences. As for the differences in various traits between the sexes, the females tended to show more favorable traits in their carcasses than the castrated males on lean meat production and so on. The results of factor analysis of all the factors involved in the meat production performance test of pigs revealed that seven factors could be extracted and the accumulated contribution ratio was 73.7%. The results of the cluster analysis revealed that three cluster could be formed according to the degrees of similarity. With the discriminatory analysis presently used for the overall judgement, a rate of fitness of 66.0% could be attained and further improvement of this figure can be expected on the basis of the results of mathematic judgement.

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An economical and efficient treatment system of waste water from pigpens was developed in a practically applicable size by separating microfine solid particles from water with a pretreatment step. This system was composed of filtration, agglutination and separation. In the filtration step, waste water of approx. 10, 000 pigs was filtered through a screen for separation of solid and large particles. In the agglutination step, a polymeric coagulant was added to the filtrate for agglutination and separation of flocculent fine particles in the filtrate and the mixture was subjected to the treatment with a multi-disk separator and activated sludge process. The microfine solid particles collected from the filtrate were collected together with excessive sludge and subjected to separation and dehydration with a multi-disk separator from the filtrate. The supernatant separated from the filtrate was treated with the activated sludge process. In conjunction with the efficiency of agglutination and separation, approx. 100mg/liter of a cationic polymer coagulant was added to the filtrate, attaining removal rates of SS (suspended solid) and BOD as high as 95.9% and 80.4%, respectively. With an amount of 50mg/liter of the addition of the coagulant, the removal rates of SS and BOD were also so good as 82.7% and 42.5%, respectively. The BOD of the supernatant after separation of the solid matter was 1, 910mg/liter, while the BOD of waste water was 8, 000mg/liter. In the activated sludge process, the BOD loading rate was 0.33kg/m³ per day and the BOD of the treated water was 44.0mg/liter. The removal rates of BOD and NH₃-N were as high as 97.7% and 98.0%, respectively. The rate of SS removal of the filtrate after separation of the sludge with the disk separator was also as good as approx. 98%.
The construction cost and the running cost of this system were approx. \5, 000/pig and approx. \1.6/pig/day. The treatment of waste water from pigpens could be substantially improved in terms of both efficiency and economy in comparison with those of the conventional methods for treatment.

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Eighty-three strains of Staphylococci isolated from skin of 30 healthy piglets of SPF swine farm and 76 strains isolated from that of 30 piglets of a conventional swine farm were subjected to identification of species and drug sensitivity test with agar dilution method. S. hominis and S. haemolyticus shared the majority of the strains isolated from the materials of both farms. There were hardly any differences noted in the bacterial species between both farms. More than 4 times higher values of 50% MIC were found out in the Staphylococci isolated from the conventional swine farm than that of the SPF swine farm in KM, CTC, and CP in the drug sensitivity test.

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It was investigated in the present study on what influences would be exerted on the total activity level of lactic dehydrogenase (abbr. as LDH) in porcine serum and the level of its isozyme by various factors such as the method for handling the test samples, along with evaluation of physiological values of fattening pigs. The following results were obtained.
1) Comparison of LDH activity level and its isozyme level in (heparinized) plasma and serum:
There were no significant differences between the levels of LDH activity and isozyme in (heparinized) plasma and serum.
2) Effect of leaving time from collecting blood till centrifugation upon the results of assay:
No appreciable effect was identified by the variation in the leaving time till 2 hours after collecting blood except for LDH₂ fraction.
3) Stability of LDH activity and its isozyme in serum: The stabilities were the highest when stored at -80°C followed by those at room temperature and those at -20°C in this decreasing order. Storage at 4°C proved a failure in maintaining the stability for a long period of time.
4) Effect of hemolysis upon assay results:
Neither LDH₂ nor LDH₃ received any influence upon their levels by the hemolysis, while perceivable influences upon assay results were initiated upon LDH activity from (_??_), and upon LDH₁, LDH₄ and LDH₅ from (+), (_??_) and (_??_), respectively.
5) Comparison between the assay results of blood from living bodies (abbr. as living) and blood discharged by bleeding (abbr. as bleeding):
Significant differences were found out between them in terms of LDH activity and isozyme level. However, there were significant correlation between living and bleeding, and the regression equations were approved.
6) Physiological value of fattening pigs:
To demonsrate the physiological values with mean ±2SD. The activity of serum LDH was 1, 270±448 Wróblewski unit. LDH₁, LDH₂, LDH₃, LDH₄ and LDH₅ were 34.1±12.6%, 21.2±5.6%, 22.1±5.0%, 11.7±5.8% and 11.1±7.4% respectively.

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In order to presume the fat percentage in carcasses of pigs, the relationship among the backfat thickness, fat area of cross section of carcass and fat percentage of carcass was investigated with 49 Landrace boars when they reached a weight of 90kg and were slaughtered. The sites of cross sectioning were the 9th, 11th, 13th and 15th thoracic vertebrae and the 1st lumbar vertebra. The thickness of the subcutaneous fat was measured at the sites of 5, 10 and 15cm apart the dorsal median line. The areas of muscle, fat and bone on the cross section were measured with a Digitizer. The residual standard error (RSE) was used so as to compare the accuracy of presumption of the fat percentage of carcass. For use as the model for presumption of accuracy of fat percentage in carcass with subcutaneous fat thickness, the best possible combinations of independent variables included 3 sites of fat thickness (10cm apart from the 13th thoracic vertebra, 15cm apart from the first lumbar vertebra and 15cm apart from the 11th thoracic vertebra) and carcass weight of right side as R² of 71.53% and RSE of 1.57. On the basis of the ratio of the area of subcutaneous backfat in the cross section, the fat percentage of carcass was presumed as R² of 72.31% and RSE of 1.39 using the three independent variables of the 11th and 13th thoracic vertebrae and the carcass weight of right side. Furthermore, when all the fat areas of cross section including the intramuscular fat were used, the fat percentage was presumed as R² of 81.04% and RSE of 1.28 using the three sites of cross sections of the 11th and 13th thoracic vertebrae and the first lumbar vertebra and the carcass weight of right side. It was found out from these results that the fat area measurement of cross sections was the most effective method for estimation of fat percentage in the carcasses of pigs. It was also suggested that the accuracy of the presumption of subcutaneous fat thickness will be improved by selecting the sites for the measurement.

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It is known that there are considerable differences in live weight of individual pigs crossbred with wild boar even when they are at the same age in months. In order to investigate the relationship between the differences in live weight and the meat quality, ten crossbred animals of the same age in months were fattened for approx. 8 months, and they were divided according to the body weights upon slaughter into the group with light weight (2 castrated males and 3 females with a mean weight of 74.9kg) and the group with heavy weight (2 castrated males and 3 females with a mean weight of 88.6kg). The differences in the carcass traits and physico-chemical properties of muscles and adipose tissues were examined, obtaining the following results.
The yield (in percentage) of dressed carcass, I and II of loin length and ratio of the middle part were significantly larger in the heavy weight group, while the ratio of hind quarters tended to be larger in the light weight group. As to the ratios of composition of bone, fat and muscle in hind quarters, the ratio of fat was significantly higher in the heavy weight group than in the light weight group, while those of muscles and bones were significantly higher in the light weight group. The loin area and fat thickness tended to be larger in the heavy weight group.
No appreciable variations were found out with animals of different body weights in terms of physicochemical properties of muscles such as chemical composition of muscle tissues and color shade of M. longissimus dorsi, but the ratio of crude fat tended to be larger in the heavy weight group.
As for the properties of back fat and kidney leaf fat, melting point of fat tended to be higher and both iodine value and refractive index tended to be lower in the heavy weight group.
In conjunction with the composition of fatty acids in the muscles, the content of oleic acid was higher and that of linoleic acid was lower in the heavy weight group than in the light weight group. The content of linoleic acid in the back fat was significantly higher in the light weight group, and the content of linoleic acid in kidney leaf fat was higher and that of oleic acid in it was lower in the light weight group than in the heavy weight group.
The above mentioned results suggested that the light weight pigs crossbred with wild boars tended to have softer fat in view of the properties of their adipose tissues and the fatty acid composition.

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