Ass. Prof. Alberto PALMONARI

Rumen is an anaerobic chamber, and it is inhabited by a dense and different strict anaerobes microbial population: Bacteria, Archaea, Fungi and Protozoa. They are involved in the fermentation and degradation of plants material which result in the conversion into digestible compounds as volatile fatty acids (VFAs) and such a source of energy. The archaeal and bacterial domains are essential for rumen activities. Many taxa are not abundant in the rumen, but they are also important for fermentation and digestion. The rumen microbiome is influenced by several factors including host genetics and species, animal behaviour, and diet’s characteristics or composition. There are different dietary interventions which could influence microbiota: improving the quality of ingredients, changing the F:C ratio of the diet, and using feed additives. In general, any activity on the diet could influence the whole rumen microbiome, and not only a specific population. Following trials were made to investigate such dynamics. First study was conducted at the Alma Mater University of Bologna dairy research farm involving 24 lactating cows, fed the same diet, but presenting different milk productions. Animals were then separated in two groups, high-producing cows (HY) and low-producing cows (LY). Rumen protozoa, ammonia (NH3) concentration, and volatile fatty acids (VFA) were analyzed. DNA from rumen was extracted, purified, and sequenced with Illumina MiSeq. For VFAs, acetic and propionic acid were different between groups (P ≤ 0.05), being the first higher in LY, while the latter in HY. No statistical difference was observed for the main protozoa genera and ammonia concentration. Ruminal microbiota composition revealed significant differences. The HY group showed a higher abundance of Lachnospiraceae (P ≤ 0.05), and Veilonellaceae (P ≤ 0.05), while Eubacteriaceae (P ≤ 0.05), and RF16 spp. (P ≤ 0.05) were higher in LY. A tendency (P = 0.10) was observed for the Prevotellaceae family, with higher values in LY compared to HY. Data obtained with the metataxonomic analysis are very interesting, since similar effects were observed in a previous in vitro study, in which we investigated the potential of molasses in modulating the rumen microbiota composition, fibre digestibility and in vitro volatile fatty acid (VFAs) production. Other than dietary composition, recent findings suggest that also the genetic potential of the animal itself would play an essential role in promoting (or weakening) the growth of specific microorganisms. In conclusion, the combination, or potential triangle, between microbial environment – genetics – specific diet, are actually offering a serious key point to reconsider and better understand the whole idea of precision feeding, moving a first very important step toward new nutritional strategies.