Enumeration of lactic acid bacteria on grass and the effects on silage fermentation of added bacteria
Year: 1990
Type: dissertation
Abstract: Initial studies on the methodology of enumerating lactic\nacid bacteria (LAB) on grass and silage indicated that (a)\nvarying the homogenisation time in a stomacher from 1 to 7\nminutes did not effect LAB numbers, (b) MRS and Rogosa\nmedia gave similar LAB counts in silage and (c) anaerobic\nincubation of plates led to higher counts of LAB from\nsilage compared to micro-aerophi1ic incubation, but\nsimilar counts from grass. A survey of LAB numbers on\ngrass grown for silage showed pre- and post- harvest values\nof 3.1 x 105 colony forming units (CFU)/g (range 1.40 x 104\nCFU/g to 1.3 x 107 CFU/g.) and 3.3 x 105 CFU/g (range 1.6 x\n104 CFU/g to 5.9 x 10° CFU/g) respectively. The numbers\nrecorded were not related to grass dry matter or water\nsoluble carbohydrate (WSC) content or to specific weather\nconditions pre- harvest. From a random selection of\ncolonies, lactobacilli accounted for 64*, leuconostoc\n25*, and streptococci 7* - of these 54* were identified as\nhomofermentative and 32* heterofermentative. Total LAB\nwere highest on dead material at the base of the crop (2.5\nx 107 CFU/g), intermediate on the lower stem and\ninflorescence and lowest on the leaf (6.0 x 104 CFU/g) and\nupper stem (2.0 x 105 CFU/g). Counts of LAB differed\nslightly across 6 grasses and one clover but were greater\nthan 10® CFU/g in all cases. LAB numbers on various parts\nof a new harvester and mower ranged from 0 to 104 CFU/cm2.\nAfter continuous use these values generally increased,\nwith 107/cm2 being recorded on the harvester chute. Where\nunwilted grass with 4 x 105 CFU/g to 9 x 10s CFU/g was\nensiled in large scale farm silos, values of 5 x 108 CFU/g\nto 1 x 109 CFU/g were found after 48 hours.
Author: Joseph M. Moran
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W1002207769