Chemical and microbial characteristics and aerobic stability of laboratory-scale unchopped alfalfa baleage: effects of lactic acid bacteria inoculation and beet molasses at two moisture levels.

Preserving alfalfa as unchopped baleage can reduce nutrient losses, but its high buffering capacity, low fermentable carbohydrate availability, and physical structure may restrict effective fermentation. This study evaluated the effects of lactic acid bacteria inoculation and beet molasses on fermentation, microbial dynamics, and aerobic stability of laboratory-scale unchopped alfalfa baleage at two moisture levels. Wilted alfalfa at 60% and 50% moisture received four treatments: untreated control, water-sprayed control, lactic acid bacteria inoculation (3 × 10⁶ CFU/g), and inoculation combined with beet molasses. Samples were vacuum-sealed, stored for 42 days, and analyzed on days 1, 7, 21, and 42. Controls maintained pH above 6 throughout storage. At 60% moisture, the combined treatment reduced pH below 4.6, whereas other additive treatments reached 4.6-5.0; inoculation alone at 50% moisture remained above pH 5. Dry matter was unaffected by treatment, while neutral detergent fiber decreased in the combined treatment at 60% moisture by day 42 (P < 0.01). Additives increased lactic acid bacteria populations and suppressed Enterobacteriaceae, while yeasts and molds were eliminated by day 21. Clostridia were unaffected. Ammonia nitrogen was higher at 50% moisture (P < 0.01), and butyric acid occurred only in controls. Acetic acid production occurred earlier and reached higher concentrations in additive-treated samples. Additives improved aerobic stability (P < 0.01), extending spoilage time by more than 109 h versus controls. Overall, wilting alone was insufficient for adequate fermentation, whereas inoculation, particularly with beet molasses at 60% moisture, produced the most favorable fermentation and aerobic stability under laboratory conditions.