Essential oils and dairy cow performance

Essential oils have been shown to favourably effect in vitro ruminal fermentation, but there are few in vivo studies that have examined animal responses. The objective of this study was to evaluate the effects of thyme (THY) and cinnamon (CIN) essential oils on feed intake, growth performance, ruminal fermentation and blood metabolites in feedlot calves fed high-concentrate diets.

Cows got the control diet (no additive), the thyme diet (5 g THY/d/calf) or the cinnamon diet (5 g CIN/d/calf). Supplementation of THY or CIN did not affect DMI and ADG, and feed efficiency was similar between treatment groups. There were no effects of additives on ruminal pH and rumen concentrations of ammonia nitrogen and total VFA; whereas molar proportion of acetate and ratio of acetate to propionate decreased, and the molar proportion of propionate increased with THY and CIN supplementation.

Rumen molar concentration of butyrate was significantly increased by adding CIN compared to control; but no change was observed with THY compared with control group. No effects of THY, or CIN were observed on valerate, isobutyrate or isovalerate proportions. Plasma concentrations of glucose, cholesterol, triglyceride, urea-N, β-hydroxybutyrate, alanine aminotransferase and aspartate aminotransferase were not changed by feeding THY or CIN.

Results from this study suggest that supplementing a feedlot finishing diet with THY or CIN essential oil might be useful as ruminal fermentation modifiers in beef production systems, but has minor impacts on blood metabolites.

Source: Asian Australasian Journal of Animal Science.