Lactic acid bacteria and enzyme inoculation of Italian ryegrass-red clover silage: enhancing microbial profile, fermentation quality, and digestibility

This study evaluated the effects of inoculating Italian ryegrassred clover with a commercial additive containing lactic acid bacteria and enzymes (LABE) on the microbial profile, fermentation quality, nutritive value, and digestibility of silages. The experimental treatments were: (1) control (without LABE); (2) LABE1 (inoculated at 1.5×105 cfu/g of ensiled mass); and (3) LABE2 (inoculated at 3.0×105 cfu/g of ensiled mass). After a 60-day incubation period, nutrient composition, fermentation characteristics, microbiology, and digestibility were determined. The pH values of the first harvest Italian ryegrass-red clover silages were 4.59, 4.15, and 4.14 for the control, LABE 1, and LABE 2 groups, respectively (P<0.05), while the corresponding values for the second harvest silages were 4.90, 4.09, and 4.14 (P<0.05). In the control silages, the lactic acid contents were 7.60 and 3.68%, for the first and second harvests, respectively. Following LABE inoculation, these values increased to 8.02 and 10.01% for the first harvest LABE 1 and LABE 2 groups, and to 6.15 and 6.38% for the second harvest treatments, respectively (P<0.05). Ammonia nitrogen concentrations did not differ in the first harvest, however, in the second harvest, the LABE2 group had higher levels (101.54 g/L) compared to control (69.66 g/L) and LABE1 (81.25 g/L) groups (P<0.05). Microbiological analysis showed a decrease (P<0.05) in total aerobic mesophilic bacteria and enterococci populations in both harvests, while lactic acid bacteria counts were unaffected. Yeast-mold, and enterobacteria counts were below detection limits (<2.3 log10 cfu/g) in all groups. Furthermore, the in vitro neutral detergent fiber digestibility values of the first and second harvest control silages were 34.97 and 32.68%, respectively. LABE inoculation increased these values to 41.13 and 35.04% for the first harvest LABE 1 and LABE 2 groups, and to 42.45 and 39.26% for the second harvest treatments, respectively (P<0.05). The population of lactic acid bacteria present in the natural microflora of fresh forage is often unpredictable. By overcoming this limitation, LABE improved the overall silage profile, as the enzymes accelerated fiber degradation, providing essential substrates for lactic acid bacteria. Ultimately, the LABE 2 treatment (inoculated at 3.0×10 cfu/g) produced the most optimal results. Consequently, these improvements in fiber digestibility are expected to positively affect overall animal performance, although further in vivo research is required to confirm these effects.