Effects of Citrus Lemon essential oil levels on ruminal fermentation of Holstein calves and In vitro digestibility

The objective of this study was to investigate the effects of different levels of Citrus Lemon essential oil on in vitro nutrient digestibility and rumen microbial fermentation in male Holstein calves. four fistulated male Holstein calves (average body weight 650± 20 kg) were allocated to five experimental diets including basic diet without additive (control), control + 300 mg Monensin, control + 600, 800 and 1000 mg lemon essential/d for five periods of 17 days and in a change-over complete randomized block design. Inclusion of 800 mg lemon essential/d decreased digestibility of dry and organic matter, but the other treatments did not have a significant effect. Inclusion of 600 and 800 mg/d of Citrus Lemon essential oil significantly decreased rumen N-NH3 concentration and the diet containing of 1000 mg/d decreased acetate to propionate ratio in rumen. The treatments had no significant effects on protozoa count and rumen pH. Generally, the results of this study showed that diets containing citrus lemon essential oil showed better performance in comparison to Monensin based diets. More investigations should be done to evaluate the effects of lemon essential oil on performance of ruminants.