Comparison of N,N-dimethyldodecanamine with antibiotics on in vitro cellulose digestion and volatile fatty acid production by ruminal microorganisms.

Eleven antibiotic compounds used in animal production, were compared with N,N-dimethyldodecanamine for their effects on in vitro cellulose digestibility and VFA production. Dose-response data were analyzed statistically to determine the concentration for each compound which would inhibit cellulose digestion of VFA production by 50%, thereby providing a convenient reference point for evaluation of the amine with respect to the antibiotics. Chlortetracycline, oxytetracycline and penicillin inhibited cellulose digestion by 17 to 35% and VFA production by 18 to 26% at concentrations of 2.5 micrograms/ml, while N,N-dimethyldodecanamine and dihydrostreptomycin at concentrations of 10 micrograms/ml inhibited cellulose digestion and VFA production by 5 to 19%. For similar inhibitive effects, bacitracin, chloramphenicol, kanamycin, sulfanilamide and sulfathiazole were required in concentrations of 25 micrograms/ml. Tylosin at a concentration of 1 microgram/ml inhibited cellulose digestion and VFA production by about 80 and 50%, respectively, and monensin was effective at 5 micrograms/ml. In general, compounds of lesser importance for growth promotion in ruminants (sulfathiazole, sulfanilamide and kanamycin) had a less inhibitory effect on cellular digestion and VFA production in vitro. N,N-dimethyldodecanamine was more effective than these compounds but repressed cellulolytic activity less than those antibiotics (chlortetracycline, oxytetraxycline and monensin) that are most effective in improving feed efficiency.