豚の生態行動に関する研究

It is of great importance to have numerical data on various fundamental aspects for design of pigpens. The present study was conducted to know the nasal physical strengths of swine in experiments for observation with an device we designed for its determination. The results were as described below.<br>(1) The action for a pig to push forward with its nose can be classified into the motion for the tip of nose to draw an arc and into the motion for the tip of nose to draw an arc and into the the one for pushing something such as the door forward with its nose. If the door was a light one a habit for a pig to push it upward as well as forward could be frequently noted.<br>(2) The maximum objective weight which could be pushed forward with its nose and which could be determined with our device amounted to 73.3kg. The theoretical torque of the material of the fence actually bent or distorted by its nose was found to be comparable to the yielding point of the material.<br>(3) The nasal physical strengths of piglets grown by outdoor feeding gained proportionately as their bodies grew up, and reached the strengths of an adult pig at their age of 220 days. In contrast, the nasal physical strengths of the piglets fattened indoor were not in parallel with the growths pf their bodies, and remained less than 20kg. Of the piglets fattened indoor, the physical strengths of the piglets under restricted feeding were greater than those of the piglets under feeding ad libitum. It was noted that there was a training effect by the feeding and controlling conditions for piglets to gain their nasal physical strengths.<br>(4) No significant difference was seen between the physiques and physical strengths of the sows.<br>(5) It can not be denied that there is still foom for modifying the device and the method for determination of the nasal physical strengths if the facts are taken into consideration that boars, could not be subjected to determination due to excitement and that the heavier the door the greater was the recorded physical strengths. However, it can be assumed that the nasal physical strengths could be determined fairly adequately if the resistance against friction when the door is slowly forced open is also taken into consideration.