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

DI LUCA FERMANDO; UEZEN DAVID; MALDONADO NATALIA CECILIA; ISLA MARIA INES; NADER MARÍA ELENA FÁTIMA; VIGNOLO GRACIELA

San Miguel de Tucumán

Simposio; V Simposio Internacional de Bacterias Lácticas (SIBAL); 2016

CERELA-CONICET

Ensiling is a preservation method for moist forage crops. Itis based on lactic acid bacteria (LAB) converting water-soluble carbohydrates (WSCs) into organic acids, (lactic and acetic acids), under anaerobic conditions. As a result, pHdecrease and moist forage is preserved from spoilage microorganisms. Corn (Zea mays) silage is the most commonlyused in feedlot-steers dietsand is often inoculated in an effort to improve their preservation andquality. 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 homolacticPediococcusacidilactici CRL2043 (LAB-1), heterolacticLactobacillus 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 7.5log 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 homolacticLAB-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.WSCsand crude protein were not significantly affected by inoculation, whilea decrease and increase in starch and neutral detergent fiber concentrations, respectivelywas observed. When aerobic stability (deterioration upon opening) of silages was investigated, mixed inoculated showed the lowest DM loss compared to the control, whereas improved aerobic stability was obtained in the presence ofL. fermentum with and without P. acidilacticiby inhibition of yeast activity.Thus, there is a potentialto add both microorganisms simultaneously to improve thefermentation and aerobic stability of corn silageas food for lot steers.