Effect of a feed additive containing yeast cell walls, clove and coriander essential oils and Hibiscus sabdariffa administered to mid-lactating dairy cows on productive performance, rumen fluid composition and metabolic conditions

Thirty-six multiparous Holstein mid-lactating cows were housed in 6 pens (6 cows/pen) and allocated in two groups (3 pens/group), receiving a control total mixed ration (CTR), or the same diet supplemented with a feed additive (TRT). Between 15 and 35 days from enrolment (DFE) the dry matter intake (DMI) of each pen, and the individual milk yield (MY), rumination time (RT), the compositions of milk and rumen fluid and the metabolic profile of plasma were monitored regularly. At 35 DFE, cows started a 1-week wash-up period prior to the changeover. Data were analysed with a mixed model using repeated measures. Cows receiving the additive had higher DMI and MY (p <.01), a longer RT between 22 and 29 DFE (p <.05), a higher total VFA concentration and a lower pH in the rumen fluid (p <.01 and p =.04, respectively). At 15 DFE, TRT cows had a higher concentration of lactose in their milk, and lower concentrations of BHB, ceruloplasmin and haptoglobin, paired with higher concentrations of albumin, paraoxonase and aspartate aminotransferase in their plasma (p <.01). These outcomes suggest a positive effect of the additive on increasing DMI and MY, possibly reflecting that it had a combined action on the rumen and the liver.Highlights The additive increased feed intake, rumination time and milk yield. It improved rumen fermentations and liver activity, and mitigated ketogenesis and inflammatory conditions. Beneficial actions of the active components on rumen and liver functions could be hypothesised.