Three castrated pigs with initial body weights of 45-48kg were exposed to extremely high temperatures in a room with controlled temperature so as to investigate the effects of severe thermal stress upon swine, by raising the temperature as time elapsed. On pig was exposed to a temperature ranging from 33 up to 37°C for 3.5 days, while another pig was exposed to a temperature in a range identical as above, but was exposed to a higher temperature up to 49°C thereafter for a total period of 4.5 days and the third pig was exposed to the temperature ranging from 23.9 to 33.7°C for 6 days on outdoor and then to abrupt rise in the ambient temperature by more than 10°C and eventually to 41°C for 4 hours. The heart rate, respiratory rate and rectal temperature were measured for all the three pigs. All of these physiological responses were intensified as the temperature was gradually elevated. The heart rate definitely increased at a temperature above 41°C. The rises in the respiratory rate and rectal temperature were found to be in an even closer relationship to the temperature than the heart rate. The rates of intensification of these physiological reactions were mild up to approx. 40°C if the temperature was elevated gradually. Their maximum values were observed in the third pig at 41°C, where the heart rate, respiratory rate and rectal temperature were 130/min, 230/min and 42.8°C, respctively. Also in the second pig, a rectal temperature of 42.8°C could be observed at a temperature of 49°C. The maximum values of the respiratory rate observed in the present study were higher than those so far reported at temperature of 32-34°C. This result revealed that pigs can tolerate at a high temperature even around 40°C by increasing their respiratory rates, and the results of observations on the heart rate and rectal temperature also proved the tolerating ability of pigs.
Taking into consideration that all the three pigs still had considerable tolerability left even when they were evacuated from the room after the measurement, it was conceived that pigs can endure the high temperature which is usually experienced in summer in Japan, if they are to tolerate the only factor of high temperature.

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Three Lanrace barrows which had been previously subjected to varying temperatures of 37°C, 41°C and 49°C, respectively, were sacrificed by blood depletion and examined histopathologically.
The results revealed mild congestion in the brain of all the three pigs. Partial edematic changes were observed around the small blood vessels in cerebeller parenchyma or choroid plexus of the lateral ventricle of two of the barrows. The check of the skeletal muscle of all the three pigs revealed sporadic presence of regressive changes such as segmental constriction, hyaline degeneration or myolysis (fusion) in their whole body (M. linguae, diaphragmatic muscle, M. longissimus dorsi, M. psoas and M. vastus tibilis). Especially, the case B which was exposed to a high temperature for a longer peiod of time developed necrosis and regressive repair to a considerable extent in M. longissimus dorsi. Although these mild lesions can not be termed as the pathological changes similar to those of heat stroke due to exposure to a high temperature, they were deemed to be of some help as the basic data of experimental thermoplegia because of scarcity of reports on morphological changes in the cases of heat stroke of swine.

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Effects of feeding period and dietary levels of kapok meal on the porcine fat were investigated in the present study using sixteen 4-month-old piglets.
All the diets were supplemented with 7% soybean oil to soften porcine fat. The feeding test was conducted with a 4×2 factorial design of dietary treatment with 4 different dietary levels of kapok meal (0, 2, 3 and 4%) and with two different feeding periods (4 and 7 weeks). The kapok meal prepared by expeller was used and its content of etherial extract and that of cyclopropenoid fatty acids (CPFA) were 8.8% and 1.34%, respectively.
The iodine number and refraction index of the fat hardly varied with the different dietary treatments. The effects of kapok meal varied with the locations of fat accumulation. There was no significant effect observed on the outer layer of back fat by feeding of kapok meal to pigs, whereas significant rises were noted in the melting points and the ratio of C 18:0/18:1 of both the inner layer of back fat and the leaf fat. In the case of 2% level, the feeding period of 4 weeks showed hardly any effects upon these measurements and that of 7 weeks was needed. In the cases of 3% and 4% levels, the feeding period of 4 weeks proved to be equally effective to that of 7 weeks, and the feeding level of 3% proved to be as affective as 4%.
These results revealed that it is necessary to provide a long feeding period for CPFA to prevent soft fat in swine if it is to be given in a low level and that its addition over a certain level can not bring about improved effects and supplementation for a shorter period of time would be sufficient.

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Levels of catecholamines in plasma were determined of six littermate piglets (Landrace×Hampshire) which were subjected to cold and handling stress given twice during their age from 2 up to 14 days, and the results were comparatively evaluated with those under normal conditions.
Normal levels were observed in the rectal temperature, milk intake and hematocrit valuse of the piglets at the time of the present experiment. Concentrations of glucose in plasma showed no change ascribable to the stresses applied. The concentrations of norepinephrine (NE) and epinephrine (E) in plasma of piglets at age less than 7 days loaded with the stress tended to be higher than those of the piglets under normal conditions, but this tendency was not clearly observed at age over 10 days. The NE/E ratio under loading of stress was significantly higher than that of the normal condition (p<0.05), and that under loading of cold stress was higher than that given handling stress.
These results indicated that catecholamine is released into blood in response to the stress and that the NE concentration under the cold stress is relatively higher than that of E.

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