Fermentation processes in alfalfa haylage without additives and with introduction of Lactobacillus plantarum strain

The optimal pH required for the functioning of proteases in alfalfa is lower than that of meadow clover or cereal grasses, and this culture is rich in protein and pectin which is not favorable for high-quality feed production. It is recommended to accelerate the acidification of the alfalfa being hayed by adding preparations of lactic acid bacteria. In the present work, for the first time in Russia, a diversity profile of haylage microbiota during fermentation was revealed using NGS sequencing. The work aimed to study the peculiarities of alfalfa fermentation during haylage with and without using Biotrof, a lactic acid bacteria-based preparation. The experiments were performed in 2018-2019. In the first experiment, the peculiarities of biochemical and microbiological processes during alfalfa haylaging were examined. Alfalfa Medicago sativa L. nothosubsp. varia (Martyn) Arcang cv. Pastbishnaya 88 was grown (experimental field, the Williams Federal Research Center for Forage Production and Agroecology, Moscow Province), cut for hay, dried in swaths for 7 hours to a dry matter content of 43.5 % and put into 0.5 l glass vessels for haylaging. The pH dynamics, ammonia, sugar and fermentation acid levels were measured on days 0, 4, 7, 14, 28, 60, and 90 of storage. The composition of the microbial community of the plant biomass and the alfalfa haylage was analyzed in dynamics using NGS sequencing according to a modified technique. In the second series of experiments, the effect of the preparation of lactic acid bacteria Biotrof (OOO Biotrof, Russia) based on Lactobacillus plantarum No. 60 on storability and biochemical parameters of the haylage from alfalfa cv. Pastbishnaya 88 biomass dried to a dry matter content of 47.6 and 51.3 %, was studied. The biomass was put into 0.5 l-containers equipped with devices for measuring evolved gases for two treatment, with no additives and upon introduction of the Biotrof preparation in the recommended dose (105 CFU/g green mass). It was shown that a short-term wilting of alfalfa biomass to the haylage moisture resulted in 0.03-0.04 % ammonia and 0.08 % butyric acid concertation followed by an increase to 0.08-0.09 and 0.13-0.14 %, respectively, when haylaging. During wilting and early fermentation, the sugar contents in the biomass increased noticeably. In addition, the wilted alfalfa accumulates at least 3.7 % of malic acid which, like sugar, can be fermented by lactic acid bacteria. Butyric acid producers, the bacteria of the Clostridiaceae family, were not detected during fermentation. During haylage storage, among the bacteria of the Clostridia class the typical rumen microorganisms were identified of the families Eubacteriaceae , Lachnospiraceae , Peptostreptococcaceae , and Ruminococcaceae . We have found a relationship between an increase in the abundance of bacteria of the genus Ruminococcus and an increase in the amount of malic acid ( r = 0.80, p £ 0.05), and also between an increase in the amount of malic acid and an increase in the number of bacteria of the phylum Bacteroides in the haylage ( r = 0.84, p £ 0.05). The accumulation of malic acid improved the fermentability of plant biomass, causing a rapid acidification of the feed to pH 4.4-4.3 due to the introduced preparation of lactic acid bacteria Biotrof. This method improved the biochemical parameters of the feed, contributing to a decrease in the butyric acid level, however, it did not lead to a noticeable improvement in the preservation of nutrients and an increase in the energy nutritional value of the dry matter of the obtained haylage due to the favorable fermentation process in dried alfalfa biomass. Acceleration of the acidification of the dried mass with the Biotrof preparation did not have a significant effect on the reduction of ammonia formation during fermentation. Staphylococcus arlettae , Salmonella subterranea , Streptococcus gordonii , and Enterococcus cecorum capable of causing diseases in humans and