Effects of a high-dose Saccharomyces cerevisiae inoculum alone or in combination with Lactobacillus plantarum on the nutritional composition and fermentation traits of maize silage

Abstract

Context The inoculation of silage with Saccharomyces cerevisiae to deliver viable yeast cells is a novel concept. Aims The effects of a high-dose S. cerevisiae inoculum alone or combined with Lactobacillus plantarum on the nutritional composition, fermentation traits and aerobic stability of maize silage were studied after 30, 60 and 90 days of storage. Methods Whole-crop maize (309.3 g dry matter (DM)/kg as fed) was subjected to one of three treatments: deionised water (untreated control); S. cerevisiae at an estimated concentration of 108 CFU/g fresh forage (S); or S. cerevisiae at an estimated concentration of 108 CFU/g and L. plantarum at an estimated concentration of 105 CFU/g of fresh forage (SL). Key results Compared with the control, the S and SL groups showed increases (P < 0.001) in average pH (3.98 in S and 4.01 in SL vs 3.65 in the control), crude protein (85 g/kg DM in S and 80 g/kg DM in SL vs 63 g/kg DM in the control) and ammonia nitrogen/total nitrogen (122.2 g/kg in S and 163.9 g/kg in SL vs 52.9 g/kg in the control) but a lower (P < 0.001) average concentration of water-soluble carbohydrate (0.9 g/kg DM in S and 0.7 g/kg DM in SL vs 2.3 g/kg DM in the control). The levels of neutral detergent fibre and acid detergent fibre were greater (P < 0.001) in S silage than in the control and SL silages, and the hemicellulose level was lower (P = 0.004) in the SL group than the control and S groups. Starch and aerobic stability were unaffected by treatment, and the average lactate and ethanol concentrations were higher (P < 0.001) in the S (53.7 g lactate/kg DM and 28.7 g ethanol/kg DM) and SL (56.9 g lactate/kg DM and 21.4 g ethanol/kg DM) groups than the control (40.1 g lactate/kg DM and 5.3 g ethanol/kg DM) over 90 days of ensiling. Conclusions Overall, a high-dose inoculum of S. cerevisiae alone or combined with L. plantarum affected the nutritional composition and fermentation traits of maize silage. Implications The inoculation of maize silage with a high dose of S. cerevisiae needs to be performed with caution.