EFFECT OF AIBELLIN, A PEPTIDE ANTIBIOTIC, ON PROPIONATE PRODUCTION INTHE RUMEN OF GOATS

Aibellin was administered in feed to goats (16 to 18 kg of BW) for 12 d. At 80 mg/d, the molar percentage of propionate in rumen fluid incre ased significantly in 8 d, and the effect lasted for as long as 10 d a fter administration ceased. Total VFA concentration, protozoa numbers, and NDF digestibility were not depressed significantly at this dosage but were reduced at 100 mg/d with little further increase in the mola r percentage of propionate. Therefore, the optimal dosage of aibellin was 80 mg/d under our experimental conditions. In contrast, monensin ( 30 mg/d) and gramicidin D (60 mg/d) decreased total VFA concentration and protozoa numbers when supplemented to obtain molar percentages of propionate comparable to 80 mg/d of aibellin. From these results, aibe llin may be easier and safer to use than monensin and gramicidin D to modify rumen fermentation.