Freeze–thaw condition limits the fermentation process and accelerates the aerobic deterioration of oat (Avena sativa) silage in the Qinghai-Tibet Plateau

Abstract

The objective of this study is to determine the effect of freeze–thaw condition on the fermentation characteristics, microbial community, and aerobic stability of oat (Avena sativa) silage in the Qinghai-Tibet Plateau. Oat forage was harvested at milk ripening stage, ensiled in vacuum-sealed bags, and then stored at (1) a constant temperature of 20°C, as a control (20 group) or (2) subjected to freeze–thaw condition (alternating 20 and −5°C every 12 h; S group). The quality and microbial community in the silage were measured after 1, 3, 7, 14, and 60 days of ensiling, and the aerobic stability was measured after 60 days of ensiling at room temperature or at the two treatment temperatures. The results showed that the higher the pH, the lower the concentration of lactic acid and the ratio of lactic acid/acetic acid of the samples under freeze–thaw condition, as compared to those stored at 20°C. The dry matter content of 20 groups was significantly higher than S group (p < 0.05). While ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and water-soluble carbohydrates (WSC) had no significant difference between two groups. Lactobacillus spp., Leuconostoc spp., and Weissella spp. were the most prevalent bacterial genera in all groups. The abundance of Lactobacillus spp. in the 20 group was the highest on day 3 of ensiling (p < 0.05), and it reached the peak on day 14 in the S group, but the abundance in the S group did not exceed 50% during whole fermentation process. The abundance of Enterobacterales and the count of Escherichia coli in the S group was significantly higher than 20 group (p < 0.05). Interestingly, the lactic acid concentration was significant correlated with Lactobacillus spp. in 20 group, while correlated with Leuconostoc spp. in S group. The aerobic stability of the S group was lower than that of the 20 group (p < 0.05). The present study indicates that the freeze–thaw condition led to insufficient fermentation degree of silage by limiting the fermentation of Lactobacillus spp. and severely reduced the aerobic stability of oat silage.

The influence of low-temperature resistant lactic acid bacteria on the enhancement of quality and the microbial community in winter Jerusalem Artichoke (Helianthus tuberosus L.) silage on the Qinghai-Tibet Plateau

“…The storage temperature significantly influences ensiling success ( Zhou et al, 2016 ). The Tibetan Plateau’s low temperatures make it prone to incomplete ensiling fermentation ( Li et al, 2022 ), but inoculating low-temperature resistant LAB offers a potential solution for winter low-temperature ensiling fermentation ( McDonald et al, 1991 ; Zhou et al, 2016 ). A pH below 4.6 during ensiling inhibits the activity of undesirable microorganisms and protein hydrolyzing enzymes ( Ogunade et al, 2018a , b ).…”

“…However, the average daily temperature during JA harvesting in Qinghai Province hovers around 10°C, occasionally plummeting to below 0°C at night. The fermentation process is inhibited at low temperatures ( Li et al, 2021 , 2022 ). In colder temperatures (<5°C), inoculating with low-temperature resistant LAB can expedite the low-temperature fermentation process, inhibit the proliferation of detrimental microorganisms, and substantially enhance silage quality.…”

Responses of microbial community dynamics, co-occurrences, functional shifts, and natural fermentation profiles of Elymus nutans silage to altitudinal gradients

“…The Qinghai-Tibet Plateau (QTP) is one of the most important alpine animal husbandry areas in China ( 1 ). However, due to the frigid environmental conditions (e.g., low temperature, strong ultraviolet radiation, and hypoxia) and the short growing season of plants in this area, an imbalance between feed supply and the nutritional demand of the area’s domestic animals inevitably occurs during the annual winter and early spring ( 2 , 3 ). Consequently, domestic herbivores experience weight loss, low milk production, and other issues ( 4 ).…”

Investigating the efficacy of an exopolysaccharide (EPS)‐producing strain Lactiplantibacillus plantarum L75 on oat silage fermentation at different temperatures

“…Oat ( Avena sativa L.) is a highly valued livestock feed due to its nutritional value, low buffer capacity and high biomass production. It is widely cultivated in northern and western China, particularly in QTP (Chai et al., 2022 ; Li, Guan, et al., 2022 ). Therefore, efficient preservation of the forage is becoming increasingly important to address the seasonal feed shortage in the QTP.…”