peppermint and pennyroyal essential oil effect on performance, rumen microbial population and some blood parameters of sheep

Background: the use of antibiotics as feed additive in animal feeds due to the appearance of residues in milk and meat and their effects on human health is restricted. two essential oils with high potential for use in ruminant diet are mentha piperita (peppermint) and mentha pulegium (pennyroyal) essential oil. objectives: this study was conducted to investigate the effects of essential oils of peppermint and pennyroyal on performance, ruminal microbial population and some blood parameters of sheep. methods: for this purpose, 9 dallagh sheep were used in a change-over design experiment in three 21-d periods (14 days as adaptation and 7 days for sample collection). experimental treatments were 1) basal diet without additive (control), 2) basal diet + 110 mg/d mentha piperita essential oil and 3) basal diet +110 mg/d mentha pulegium essential oil. sheep were kept in individual cages and had free access to food and water. rumen fluid was collected before, 4 h and 8 h after morning feeding and a blood sample was obtained 3 h after morning feeding at the last day of each period. results: essential oils had no effect on performance, blood parameters, ph, ammonia, protozoa, and total viable bacterial count of rumen. coliforms of rumen fluid significantly decreased at 4 h and increased 8 h after morning feeding following peppermint and pennyroyal supplementation, respectively (p<0.05). acid lactic bacteria count was significantly higher at before and 4 h after morning feeding in pennyroyal treatment compared with other treatments. conclusions: although essential oils of mentha piperita and mentha pulegium had some effects on rumen microbial population they had no significant effects on performance and blood metabolites of dallagh sheep.