LACTIC ACID BACTERIA AS INOCULANTS FOR CORN (Zea mays) SILAGES USED TO FEED FEEDLOT STEERS

DI LUCA, F.; UEZEN, J.D.; MALDONADO, N.; ISLA, M.I. ; MORENO, A. ; RODRÍGUEZ, F.; NADER, M.E.F.; VIGNOLO, G.

Tucuman

Simposio; V International Symposium on Lactic Acid Bacteria (SIBAL). Benefitting from lactic Acid Bacteria. Progress in Health and Food.; 2016

CERELA-CONICET

Ensiling is a preservation method for moist forage crops. It is based on lactic acid bacteria (LAB) converting water-soluble carbohydrates (WSCs) into organic acids, (lactic and acetic acids), under anaerobic conditions. As a result, pH decrease and moist forage is preserved from spoilage microorganisms. Corn (Zea mays) silage is the most commonly used in feedlot-steers diets and is often inoculated in an effort to improve their preservation and quality. In this study, the performance of LAB strains inoculated in whole-crop corn forage silage containing 30-35% dry matter (DM), during 45 days-fermentation at 23 ºC was evaluated. Corn minisilos were individually inoculated with the homolactic Pediococcus acidilactici CRL2043 (LAB-1), heterolactic Lactobacillus fermentum CRL2085 (LAB-2) and with the two strains combined (LAB-mix) at an initial concentration of 5.0 log CFU/g. Minisilos were sampled at 0, 10, 20, 30 and 45 days after ensiling for microbiological and physicochemical analysis. Results showed total mesophyle in inoculated silages ranged from 6.0 to 7.5 log CFU/g. Although an initial decrease in LAB counts were observed, this population in the inoculated minisilos reached final counts between of 6.5 and 7.2 log CFU/g; those inoculated with P. acidilactici exhibited the lowest numbers. In addition, yeasts and moulds showed a higher growth in silages inoculated with the homolactic LAB-1 compared with samples inoculated with LAB-2 or LAB-mix. During fermentation, pH values decreased from 5.8 in fresh corn to around 3.6, P. acidilactici inoculated silage showing the higher acidifying rate. Physicochemical data during corn silage fermentation indicated DM loss, while WSCs and crude protein were not significantly affected by inoculation. A decrease and increase in starch and neutral detergent fiber concentrations, respectively was observed. When aerobic stability (deterioration upon opening) of minisilages was investigated, mixed inoculated showed the lowest DM loss compared to the control, whereas improved aerobic stability was obtained in the presence of L. fermentum with and without P. acidilactici by inhibition of yeast activity. Thus, there is a potential to add both microorganisms simultaneously to improve the fermentation and aerobic stability of corn silage as food for lot steers.