Journal of the Society of Agricultural Structures, Japan

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Livestock feces has the potential to be a useful biomass resource, but the majority of livestock feces (90 %) is composted, which has resulted excessive amounts of compost. To rectify this problem, livestock feces will need to be utilized to produce other materials. In this study, we focused on Polyhydroxyalkanoate (PHA), a biodegradable plastic, and confirmed the presence of PHA-accumulating bacteria in cow feces by measuring the amount of these bacteria and total bacteria found in the feces from three dairy milking cows (Holstein) and three fattening beef cows (Japanese black cattle) from A farm and B farm in Tochigi prefecture (n=12). PHA-accumulating bacteria were counted using the double staining method with Nile blue A and DAPI (4’,6-diamidino-2-phenylindole) stain. The average number of PHA-accumulating bacteria and total bacteria were 1.0-11.0 × 107 cells/g-wet basis and 5.4-50.4 × 107 cells/g-wet basis, respectively. The ratio of PHA-accumulating bacteria to total bacteria was 18.5-20.9 %. There was no significant difference between the number of PHA-accumulating bacteria in the Holsteins and that of the Japanese black cattle, however, there was a significant difference between the Holsteins from the two farms. This difference may be due to the type and amount of feed given at the two farms. The ratio of PHA-accumulating bacteria to total bacteria was approximately 20 %, regardless cow species.

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