The present study was conducted to clarify the seasonal variations in the results of fattening and the properties of adipose tissues of pigs housed in vinyl-film-covered pigbarn in which fermentation floor was designed, as compared with the pigs housed in conventional pigbarn.
The results of fattening of 460 pigs and the findings on the fatty acids and melting points of adipose tissues of 137 pigs housed in vinyl-film-covered pigbarns in Shonai District of Yamagata Prefecture were evaluated by classification into four seasons. The results revealed that the thickness of backfat of pigs which were housed in conventional pigbarns in winter tended to be thinner than the pigs housed in summer likewise. As to the causes of adverse grades of dressed carcasses, rates of thin and soft fat of pigs which were housed in winter were higher, whereas, the pigs housed in vinyl-film-covered pigbarns showed thick backfat throughout the four seasons. Daily gains and feed conversion ratios for the pigs housed in vinyl-film-covered pigbarns tended to be more excellent and remained stable throughout the four seasons. The subcutaneous adipose tissues of pigs housed in conventional pigbarns in winter contained higher proportions of unsaturated fatty acids and had lower melting points than those in summer. The subcutaneous and perinephric adipose tissues of the pigs housed from autumn to winter in the vinyl-film-covered pigbarns likewise tended to contain higher proportions of unsaturated fatty acids. The concentrations of unsaturated fatty acids of subcutaneous adipose tissues of the pigs housed in vinyl-film-covered pigbarns was, however, lower (63.4%) than that of the pigs housed in conventional pigbarns in winter (66.5%) and remained stable throughout the four seasons. The concentration of linoleic acid tended to be similar to that of the unsaturated fatty acids and the melting point of the fat was high in the pigs housed in vinyl-film-covered pigbarns.
These results indicate that the pigs housed in the vinyl-film-covered pigbarns tended to show less frequencies of thinner and softer fat and less susceptible to seasonal variations for growth than the pigs housed in the conventional pigbarns.

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The production structure in the U. S. hog industry has observed drastic changes in recent years, and these changes are derived from the technical developments since 1970s. These developments depended on capitalintensive production and the scale-up of the hog industry became even clearer as the size of the production units became bigger and bigger. As a result, family-owned farms which are more specifically and intensively engaged in hog industry grew more popular ane the forms of business operations in this industry have been changed into those of partnership or corporation. In this article, we analyzed the processes of technological developments and management styles in U. S. hog industry in order to discuss the effects of economics of scale in competition in various regions.
The hog production in corn-belt states used to be of smaller scales, and the management of the hog industry in these areas used to be combined with self-supplied feedstuff from farms. The developments of the technology, e. g. in nutrition and housing, were more or less inhibited until the 1960s. However, the shift from pasture-farming system into overall house-feeding system contributed to labor-saving and improvement of feed efficiency in the phases of farrowing, nurseries and growing-finishing.
The operation consistent from farrowing up to finishing was a dominant form in the regions surrounding the corn-belt states hand in hand with the feeder pig finishing operations in the corn-belt states and the system for management was then differentiated more or less, but the operation consistent from farrowing up to finishing remained predominant. The large-scale hog industry operations could be materialized in the Southeastern states where the operation used to be more dependent upon the commercial feed than in the corn-belt states. This trend was especially clear in North Calorina State which is geographycally close to the big market in the Eastern states. A little behind this trend, growth of large-scale operations could be noted also in the corn-belt states, where the overall economic conditions are gerenally more advantageous than in the Southeastern states. This advantage can be claimed to be attributable to the fact that the operations in the corn-belt states are based on diversified sources, whereas those in the Southeastern states are based on family-owned intensive style which is more dependent upon the self-supplied feedstuff.

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The genetic variations of blood groups and biochemical polymorphisms in Jinhua pigs, a Chinese pig breed, were investigated in this study as one of the attempts to investigate the genetic properties of the pig breed which is being brought into Japan in recent years. The blood samples were collected from eighteen (5 males and 13 females) of the pig breed which were introduced into four stations in Japan. Blood types investigated comprised eight blood groups (A, E, F, G, H, K, L and O), five serum proteins (Tf, Pa, Hp, Cp and Am), five red cell enzymes (PHI, 6PGD, PGM, ADA and EsD) and two serum allotypes (PSA-I and PSA-II), 20 loci in total.
The results were as follows.
1) There were no variations in F, G, K, L, Pa, Cp, Am, PHI, 6PGD, PGM, ADA, EsD and PSA-II loci, while the other seven loci were found polymorphic in Jinhua pigs. When the gene frequencies in Jinhua pigs were compared with those in Meishan, Taoyuan, Short-ear and Ohmini pigs, those in Jinhua pigs were characteristic in A, H, Am and 6PGD loci.
2) The genetic variability of Jinhua pigs analyzed by H. I., H, Ppoly and Ne was the lowest among the twelve different pig breeds studied (Jinhua, Meishan, Taoyuan, Short-ear, Ohmini, Göttingen, Pitman-Moore, Landrace, Large White, Hampshire, Duroc and Hypor).
3) Using the gene frequencies in the 20 loci, the genetic distances were calculated among twelve pig populations on the basis of the two formulae of Rogers and Nei, and the dendrogram showing genetic similarities among them was made. It was clarified from the dendrogram that Jinhua pigs belonged to Asian pig groups which were thoroughly different from Euro-American group, and was in a close distance to Meishan pig breed.

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A trial apparatus for testing respiration of poultry of open type and of weight model (HALDENE Type) was modified in this study for use in piglets. Its performance and capabilities were examined by its actual applications to the piglets. The following results were obtained.
(1) Blank test: Tests were conducted on whether or not carbon dioxide gas and moisture from the atmosphere brought into the chamber could completely be eliminated by the CO₂ and H₂) removal kit with three different amounts of aeration of 3 liters/min, 6 liters/min. and 8 liters/min. The results revealed that carbon dioxide gas and moisture were completely removed with an aeration amount of 8 liters per minute.
(2) Recovery test of moisture and carbon dioxide gas: Recovery test of moisture and carbon dioxide gas which were generated in the chamber was conducted to find that the recovery rate with an aeration amount of 6 liters/min. proved to be the best possible showing that of moisture bnd that of carbon dioxide gas as 100.5±0.33% and 99.5±0.10%, respectively, while the recovesy rate with 8 liters/min. tended to be lower.
(3) Test on the limit of carbon dioxide gas absorption: In order to find the limit amount of absorption of carbon dioxide gas generated in the chamber with the carcon dioxide gas absorption set, tests were conducted with five diffenent amounts of carbon dioxide gas of 80g through 160g which was generated in the chamber. The results showed that the recovery rate of 80g yielded the highest value of 99.7±0.08%, and the performance of the set was lower as the volume of carbon dioxide gas increased toward 160g.
(4) Experiments with actual use of F₁ piglets: (Berkshire×Sus scrofa):
The results of test on the respiration of the piglets weighing approx. 18kg revealed that the consumption of oxygen, generation of carbon dioxide gas RQ and generated heat per hour were 0.674±0.022 liter/kg^0.75, 0.666±0.026 liter/kg^0.75, 0.989±0.003 and 3.38±0.11kcal/kg^0.75, respectively.
Results of high accuracy can therefore be expected when this apparatus is applied to respiration test of piglets with an aeration amount of 6 liters per minute, for tests on 8 hours per day.

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The effects of carbetocin (a long-active oxytocin), oxytocin and prostaglandin F_2α (PG) on clinical findings and blood characteristics were investigated with swine in this study. Six healthy post-weaning sows weighing 195 up to 300kg were given 0.2mg of carbetocin, 25IU of oxytocin, and 10mg of PG by intravenous injection on the first, second and third days, respectively. The check was made at 0, 30, 60, 90 and 120 minutes after each injection. Transient flush of skin, vomiting, urination and defecation were clearly noted since immediately after injection of PG, which lasted for approx. 30 minutes. However, no adverse effect upon the clinical findings was found out with the other two agents.
The heart rate of the sows in the group of oxytocin injection at 120 minutes after its injection significantly increased over the value at 0 minute after the injection. The body temperature fairly rose up after injection of any of the three tested agents, but no significant change was found out in the body temperature, pulse rate or respiration of any animal except the increase of heart rate at 120 minutes after injection of oxytocin.
The values of erythrocytic elements (RBC, Hb and Ht) demonstrated substantial variations, and significant rises were noted in the Hb values of the carbetocin and oxytocin groups. There were no significant changes in the leukocyte counts or total plasma protein values.

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