Effect of a dual-purpose inoculant on the quality and nutrient losses from corn silage produced in farm-scale silos

The effects of air stress during storage and low packing density on the fermentation and aerobic stability of corn silage inoculated with Lactobacillus buchneri 40788

We determined if a microbial inoculant could improve the fermentation and aerobic stability of corn silage subjected to various challenges during storage that included an air stress challenge and low packing density. In Experiment 1, whole-plant corn was untreated (CTR) or treated (INO, Lactobacillus buchneri 40788 and Pediococcus pentosaceus 12455. Five individually replicated 7.5-L silos, at a density of 240 kg of dry matter (DM)/m³, for each treatment were kept sealed (NAS) for 19 wk, air stressed early (ES, 3 h/wk for wk 1-9), or air stressed late during storage (LS, 3 h/wk for wk 10-19). Inoculation increased the number of agar-culturable lactic acid bacteria regardless of air stress status, but it did not affect the relative abundance of Lactobacillus. Early, but not late air stress, resulted in silages with a higher relative abundance of Acetobacter when compared with NAS. Silages treated with INO had greater concentrations of acetic acid than CTR. Numbers of yeasts were lowest for INO regardless of air stress and CTR-LS had the most yeasts among all treatments. Silages that were not air stressed had a higher relative abundance of Candida tropicalis than air stressed silages. Monascus purpureus was detected in ES and LS but not in NAS, and its relative abundance was numerically higher in CTR-ES than in INO-ES and statistically higher in CTR-LS compared with INO-LS. Early air stress numerically reduced aerobic stability compared with NAS, and there was a statistical tendency for lower stability in LS compared with NAS. Inoculation improved aerobic stability regardless of when the air stress occurred. In Experiment 2, corn silage was prepared with the same primary treatments of CTR and INO but was packed at a low (LD; 180 kg of DM/m³) or a normal (ND; 240 kg of DM/m³) density and sealed (NAS) or air stressed (AS; 24 h on d 28, 42, and 89) for 92 d of storage. The concentration of acetic acid was greater in INO compared with CTR and in AS compared with NAS. Numbers of yeasts were lower in NAS compared with AS regardless of inoculation and they were lower in INO-AS compared with CTR-AS. Treatment with INO improved aerobic stability but the improvement was better in NAS versus AS and better in ND versus LD. Overall, our experiments corroborate past findings showing that INO markedly improves the aerobic stability of corn silage but they are the first to show that improvement can be sustained even when the silage was exposed to regular air stresses and when packed at a low density.

Application of condensed molasses fermentation solubles and lactic acid bacteria in corn silage production

BACKGROUND

The aim of this study is to investigate the application of two lactic acid bacteria and dry condensed molasses fermentation solubles (CMS) in the making and preservation of corn silage. Forage corn materials are divided into eight treatment groups as follows: (i) control, (ii) B2 (Lactobacillus plantarum B2, 1 × 10⁹ cfu kg^-1 ), (iii) LAS (Lactobacillus buchneri 40788, 3 × 10⁸ cfu kg^-1 ), (iv) B2 + LAS, (v) CMS (35 g kg^-1 , fresh weight), (vi) B2 + CMS, (vii) LAS + CMS and (viii) B2 + LAS + CMS. The silage composition and aerobic stability are determined after ensiling for 90 days. Furthermore, the digestibility of the silage product and gas production are evaluated using a trotro digestion procedure.

RESULTS

The assay results indicate that the CMS supplementation and B2 inoculation significantly increased lactic acid concentration (P < 0.01). However, they also reduced the content of acetic acid and silage pH at the initial fermentation stage. The CMS supplemented with B2 (B2 + CMS) showed an improvement in the quality of silage, but a significant decrease in aerobic stability (P < 0.01). The B2 + LAS + CMS treatment yielded an increase in acetic acid production during the late fermentation period and is able to extend the aerobic stability of corn silage. Furthermore, this study shows that CMS supplementation alone can significantly improve the digestibility of the in vitro dry matter (P < 0.01) and the microbial protein synthesis efficiency (P = 0.01). In addition, the CMS supplementation is beneficial for enhancing the aerobic stability of corn silage.

CONCLUSIONS

These results suggest that the combination of CMS supplementation and a suitable inoculation lactic acid bacterial strain can be highly promising for enhancing the higher quality and stability of corn silage. © 2020 Society of Chemical Industry.

A meta-analysis on the effectiveness of homofermentative and heterofermentative lactic acid bacteria for corn silage

AIMS

This meta-analysis aims to assess the effect of lactic acid bacteria (LAB) inoculation on fermentation parameters, microbiological composition and aerobic stability of corn silage.

METHODS AND RESULTS

Databases (PubMed, ScienceDirect and Scopus) were searched from 1980 to 2017. The criteria for inclusion were: randomized and controlled experiments using corn silage and published in peer-reviewed journals. The meta-analysis showed that LAB supplementation increased pH, acetate and propionate concentrations, and decreased acid detergent fibre, water-soluble carbohydrates and ammoniacal nitrogen (NH3 -N) compared to controls in the pooled raw mean difference random effect model. In addition, inoculation reduced counts of yeasts and moulds, increased LAB counts and markedly improved aerobic stability in corn silage. However, results indicated that the effect of inoculants may differ depending on the administration of homofermentative or heterofermentative LAB.

CONCLUSIONS

For the development of functional bacterial inoculants, both types of LAB should be used.

SIGNIFICANCE AND IMPACT OF THE STUDY

To our knowledge, this is the first meta-analysis to compare the application of homofermentative and heterofermentative LAB for corn silage.

Effect of microbial inoculants on fermentation quality and aerobic stability of sweet potato vine silage

Objective

This study was conducted to evaluate the effect of homo or hetero fermentative inoculants on fermentation quality and aerobic stability of sweet potato vine (SPV) silage containing Italian ryegrass hay as moisture absorbent.

Methods

The SPV was harvested at 15% dry matter, mixed with Italian ryegrass hay at 1:1 ratio on a fresh weight basis, and chopped to 3 to 5 cm length. After then, the chopped forage mixture was ensiled into 20-L mini silos in quadruplicate for 7, 48, and 100 days after application of microbial inoculants at 1.2×10⁵ colony forming units (cfu)/g of forage following: no inoculant (CON), Lactobacillus plantarum as a homo fermentative (LP), Lactobacillus buchneri as a hetero fermentative (LB), and mixture of LP and LB at 1:1 ratio as a combo fermentative (MIX).

Results

The LP and MIX silages had lowest pH (p<0.001) on 7 and 48 days, while MIX and CON silages had greatest lactate concentrations (p<0.05) on 7 and 48 days, respectively. Acetate concentrations were highest (p<0.01) in LB and MIX silages on 7 days, and in LB silage on 48 days, while lactate to acetate ratios were lowest (p<0.001) in LB silages. The chemical compositions and nutrient digestibility of silage ensiled for 100 days was not affected by inoculants. On 100 days of ensiling, LB silage had lowest (p<0.01) lactate concentration and lactate to acetate ratio, but highest acetate concentration. Aerobic stability was highest (p<0.001) in LB silage followed in MIX silage. On contrast, LB silage had lowest (p<0.05) lactic acid bacteria and mold.

Conclusion

The results indicated that application of LB solely had a better effect on aerobic stability than not only LP, but also MIX. However, LP application did not show beneficial effects from the viewpoints of fermentation quality and aerobic stability compared to CON.