Submitted to: International Silage Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2005
Publication Date: 7/3/2005
Citation: Muck, R.E., Filya, I., Contreras-Govea, F.E. 2005. Inoculant effects on ensiling and in vitro gas production in lucerne silage. In: Park, R.S., Stronge, M.D., editors. Silage production and utilisation, XIVth International Silage Conference, July 3-6, 2005, Belfast, Northern Ireland. p. 204. Interpretive Summary:
Technical Abstract: Our objective was to study how inoculation of alfalfa silage affected in vitro gas production. Alfalfa harvested with standard field equipment was ensiled in two trials, first [48% dry matter (DM)] and second cut (39% DM), in 1-l and 500-ml glass jars in first and second cut, respectively. Each trial had fifteen treatments (uninoculated control, 14 inoculants), four silos per treatment. Eight inoculants were commercial products; the others were single strains provided by two companies. All inoculants were applied at 10^6 colony-forming units (cfu)/g crop (not label rates). Silages were stored for a minimum of 30 d at 22°C. A portion of silage was wet ground in a Büchi mixer. In vitro gas production was measured on 1-g samples of the wet-ground silage in 160-ml Wheaton bottles. Three replicate in vitro analyses was performed, one on fresh ground silage and two using frozen silage. In vitro analysis was carried out at 39°C, and gas pressure was measured at 3, 6, 9, 24, 48 and 96 h. At 96 h, the bottles were opened, and pH was measured. In first cut, the natural lactic acid bacterial population at ensiling was 1.5 x 10^5 cfu/g, and all inoculants except one reduced pH relative to that of the control. The commercial homofermentative inoculants produced the largest reductions in pH whereas the two Lactobacillus buchneri inoculants produced the smallest reductions as expected. In second cutting, the natural population (2.7 x 10^7 cfu/g) at ensiling was high. The commercial homofermentative inoculants were the only treatments producing lower pH values than the control. The highest pHs were the L. buchneri inoculants. Our expectations were that inoculants would improve in vitro DM digestibility, resulting in increased gas production. Surprisingly inoculants had either no effect on 96-h gas production per g DM or gas production was reduced. In vitro fluid pH values at the end of an analysis run did not differ across treatments. Correlation analysis did not show consistent effects between cuttings. In first cut, gas production was correlated positively with silage pH, negatively with silage lactic acid concentration. In second cut, gas production was correlated positively with silage acid detergent lignin and hemicellulose concentrations. These results indicate that inoculation of alfalfa at ensiling is affecting in vitro fermentation, but silage fermentation products or fiber fractions could not consistently explain differences in gas production.