Abstract:
The prohibition of the use of growth promoting antibiotics in animal feeds within the
European Union (EU) and some other countries has led to an increased interest in alternative
means of manipulating rumen fermentation. The objectives of our study were to determine the
effects of alternative natural feed additives, essential oils (EO, Oleobiotec) and rumen specific
live yeast (LY, Levucell), to monensin (MO) and their effects on rumen fermentation and in
sacco NDF, starch and N disappearance.
The study consisted out of four rumen cannulated lactating Jersey cows that were used in
a 4 x 4 Latin square design experiment. The four experimental treatments were: 1) Control
(C), a lucerne hay/maize based TMR (10.7 MJ ME/kg, 17% CP, 32.1% NDF), 2) C + MO, 3)
C + EO, 4) C + EO + LY. The experimental periods were 25 days with the last four days for
rumen sampling and the in sacco study.
Mean ruminal pH ranged between 5.80 and 6.02 and tended (P < 0.10) to be lower in the
control cows compared to the other treatments. Total VFA production, acetate : propionate
ratio and rumen ammonia nitrogen concentration did not differ (P > 0.05) but lactic acid
concentration tended to be lower for the C + EO treatment when compared to MO
supplemented cows. In sacco TMR starch disappearance after 24 hours were higher for the C
+ EO treatment when compared to the C and C + EO + LY treatment groups (P > 0.05). Milk
production and DMI did not differ (P > 0.05) but fat % was higher for EO supplemented cows
(4.52%) when compared to C cows (4.32%) (P < 0.05). Results suggest a negative interaction
between the essential oil and live yeast products used in this study. More research is needed on
potential complimentary effects and interactions between feed additives.
