Preservation characteristics and bacterial communities of crimped ensiled barley grains modulated by moisture content and additive application

Abstract

Information about the relationships between preservation characteristics and main bacterial communities of fermented feeds can guide decision making during feed preservation and silage additive development. The objective was to evaluate fermentation quality, aerobic stability, microbial quality and bacterial profile of crimped barley grains ensiled under three moisture contents (MC): 228 (low MC), 287 (medium MC) and 345 (high MC) g/kg fresh matter; and using four additive treatments: 1. Control (CONT), 2. Formic and propionic acid-based additive (FPA), 3. Inoculation with homofermentative and heterofermentative strains of lactic acid bacteria (LAB), and 4. Salt-based additive (SALT). There was a quadratic effect (p < 0.05) of incremental MC on pH where greater decline happened from low (5.81) to medium (4.83) MC than from medium to high (4.28) MC, while lactic acid concentration and aerobic stability increased in a linear manner (p < 0.05). Ammonia-N and acetic acid concentrations increased quadratically (p < 0.05) with increasing levels of MC. The effects of additives depended on MC so that improvements in preservation characteristics in response to LAB and SALT were observed at medium and high MC, while FPA was effective at all MC levels. A minor shift was observed in bacterial ecology from raw material towards low MC samples, with Erwiniaceae sp., Enterobacterales spp. and Pseudomonas dominating the fermentation. A major change occurred in medium and high MC materials, where Fructilactobacillus dominated the fermentation in CONT, FPA and SALT silages. LAB-treated silages at medium and high MC resulted in a distinguished pattern with dominance of Lentilactobacillus followed by Lactiplantibacillus. Most abundant communities in the samples, such as Fructilactobacillus, Erwiniaceae sp., Enterobacterales spp. and Pseudomonas, were correlated with several fermentation characteristics. Our results showed that crimped barley grains could be successfully ensiled under various MC and additive treatments. Low MC feeds had higher risk to be aerobically unstable while high MC resulted in more extensive fermentation, with potentially poor fermentation quality. The suitable additive depends on the raw material characteristics as LAB and SALT require relatively high MC to be effective, while FPA showed consistent improvements over all MC levels used in the current study. Awareness of the MC of grain prior to ensiling allows to identify the risks to preservation quality and provides information for choosing an effective additive.

The Effects of Grass Silage Additive Type and Barley Grain Preservation Method on Rumen Function, Microbial Ecology, and Energy Metabolism of Dairy Cows

“…Barley grain preservation method affected barley associated microbiota. The bacterial composition of fresh crimped barley in our previous study [9] was dominated by Proteobacteria (77%), Actinobacteriota (10%), Firmicutes (9%), and Bacteroidota (3%), which are phyla commonly detected in various seeds [35,36]. The bacterial composition of dried barley in this study resembled the composition of fresh barley and was dominated by Proteobacteria, especially members from Pantoea and Pseudomonas genera.…”

“…In the current material the reduction in starch during ensiling was 20 g/kg DM, and concomitant formation of fermentation end products (ethanol, lactic acid, and acetic acid) was 28 g/kg DM. The extent of fermentation is highly dependent on the moisture content of the grains [9], and the results obtained in the current experiment can be considered typical for this type of a raw material.…”

“…Franco et al [6] demonstrated, in a pilot-scale ensiling experiment, that the same grass material treated with a homofermentative LAB inoculant contained 76 g water soluble carbohydrates (WSC) and 115 g lactic acid per kg DM compared with the respective concentrations of 195 and 2 g/kg DM for a silage treated with a commercial application level of a formic and propionic acid-based additive. Similar effects, although to a smaller extent, can be expected when dry and high-moisture ensiled grains are compared due to a partial conversion of carbohydrates to fermentation end products during preservation of moist grains [7][8][9]. Depending on the nature of substrates provided in the diet, different fermentation end products produced by the rumen microbes are provided to the host animal [10].…”

“…Demultiplexing, adapter removal, and sorting sequences by barcode were performed by the sequencing center. Sequence read quality control was performed using DADA2 [21] following the default settings in Qiime 2 [22] as described in [9] for feed samples and in [16] for rumen samples.…”

Efficacy of six lactic acid bacteria strains as silage inoculants in forages with different dry matter and water‐soluble carbohydrate content

“…In contrast, the preservation of crimped ensiled barley grains with low, medium, and high moisture contents was dependent on the additive type, that is microbial‐ and salt‐based inoculants required high moisture content. In contrast, formic and propionic acid‐based additives showed consistent improvement, regardless of the moisture content (Franco, Tapio, et al, 2022). In addition, inoculation of high and low DM alfalfa forages with L. plantarum 24–7 g for 60 days showed ameliorated silage quality compared to the control, which was more pronounced at high DM than low DM (Zhang et al, 2021).…”