Effects of Thymbra capitata essential oil on in vitro fermentation end-products and ruminal bacterial communities

13 páginas, 5 figuras, 3 tablas.

An in vitro trial was carried out to investigate the effects of natural Thymbra capitata essential oil (NEO) and its main compounds [including carvacrol, p-cymene, γ-terpinene given alone or in a synthetic combination (SEO)] on ruminal fermentation and the bacterial community using batch cultures inoculated with ruminal digesta and incubating two different basal diets [high-forage (F) and high-concentrate (C) diet]. After 24 h of incubation, primary fermentation end-products [gas, methane, volatile fatty acids (VFAs) and ammonia] and rumen microbial diversity were determined. NEO reduced the total VFA concentration (P 0.05) by any of the experimental treatments or diets evaluated. Microbial diversity analysis showed only a moderate effect of carvacrol and SEO on 13 genera, including, mainly, Atopobium and Blautia (involved in subacute ruminal acidosis) or Candidatus Saccharimonas (related to laminitis). In conclusion, T. capitata EO has a limited potential to attain nutritional or environmental benefits, but further research should be carried out to clarify its effects on animal health and microbial food safety.

Tis work was funded by CSIC (Proyectos Intramurales Especiales, 201940E115) and MUR (Direzione Generale dell’internazionalizzazione e della comunicazione Programma cooperazione internazionale PRIMA—Decreto Ministeriale 26 luglio 2016 n. 593) in the context of the MILKQUA-H2020-PRIMA 2018—Section 2. Alba Martín gratefully acknowledges receipt of a pre-doctoral grant (PRE2019-089288) from Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033, "El FSE invierte en tu futuro").