Evaluation of nutritional significance and microbial production of 1, 2-propanediol in silage

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This research was aimed to identify microbial factors responsible for 1, 2-propanediol formation in silage. The value of dietary 1, 2-propanediol in ruminants was also investigated.From a mixed silage primarily containing wet brewers grains, a 1, 2-propanediol producing microorganism was isolated. This gram-positive, catalase-negative and heterofermentative lactic acid bacteria was identified as Lactobacillus buchneri. When L. buchneri was inoculated to whole-crop maize and grasses, significant amounts of 1, 2-propanediol were produced in the silages. The production was coupled with a decrease in lactate and an increase in acetate, and was enhanced when storage period was prolonged The highest content was 77 g/kg DM in this study.Aerobic stability of silages was considerably improved when L. buchneri was inoculated, probably because the increased acetate could act as an antimicrobial component and lower yeast population during ensilage.Exogenous 1, 2-propanediol was degraded by rumen microorganisms and the ratio of acetate to propionate decreased, while not affecting the intake and preference of total mixed ration. Also, the intake of total mixed ration was not altered, when L. buchneri inoculated silage was incorporated.It is concluded that L. buchneri can be a major 1, 2-propanediol producing microorganism in silage and could be used as a novel additive to inhibit aerobic deterioration. The intake and preference of diets would be unaffected by 1, 2-propanediol, when inoculated silages were offered as ingredients of total mixed ration.