Abstract
The author carried out comparative analysis of physical and chemical properties of house dusts collected from 4 fattening swine houses in Chiba Prefecture. The comparison was made between these samples and one sample each of feed, feces of pigs and dusts of broiler house.
The results were as summarized below.
(1) The contents of organic substances (84.03-85.62%), nitrogen (4.23-4.69%) and carbon (37.52-42.78%) of house dusts indicated values similar to those of feces of swine, and were rated as between those of the feed for fattening swine and those of the dusts in the broiler house.
The existence of starch in the content was verified by the iodine test of the house dusts, which was rated as ++ comparable to that of feces of swine, but was less than that of the feed of +++. A larger amount of iodine tincture was needed for the iodine reaction of house dusts than that needed for the feed or the feces of swine. The pH of the house dusts was found to be slightly alkaline, unlike that of the feed which was acidic.
(2) The bulk density of house dusts of swine houses was 0.404-0.432 when sparsely filled, 0.564-0.590 when densely filled, and 0.498-0.532 when measured by Yamanaka's apparatus for measuring bulk density. These results were intermediate between that of the feed and that of the house dusts from broiler house. The angles of repose were estimated as 41.1-44.9°, which were lower than those of feed and those of broiler house.
(3) The ratio of dusts held on a tray of electronic balance and the time required for reaching its end point were measured with the behaviors of dusts. The former was 0.743-0.853 and the latter was 25.3-36.0 seconds. These values also were intermediate between those of feed and those of dusts of broiler house.
(4) The wind velocity for moving the dusts was classified into five stages of the first particle movement, the second particle movement, top particle movement, temporary stability and the movement of its major part.
While there were no appreciable variations among the samples of the house dusts in terms of the wind velocity inducing the first particle movement, but as the wind velocity was gradually intensified, the variations among them became bigger in terms of the behaviors of the dusts. The dusts of swine houses could be moved by higher wind velocity than that for the dusts of broiler house, but by lower wind velocity than that for the feed.
From the above-mentioned results, it could be conceived that the house dusts in fattening swine houses were mainly derived from the feces of swine.
