Four digestion experiments with 5 wethers each (0, 15, 30 or 60 mg
avoparcin per animal and day), three individual feeding experiments (28, 18 or 56 bulls per experiment; 0 and 150/200; 0, 250 and 500 or 0 and 200 mg
avoparcin per animal and day in the experiments 1, 2 or 3) and two group feeding experiments (60 bulls and 161 heifers per experiment;
salt lick stones without or with 2.5 g
avoparcin per kg) were carried out in order to investigate the influence of
avoparcin on apparent digestibility, figures of rumen fermentation, fattening and slaughtering results as well as
protein, fat and energy retention.
Avoparcin supplementation did not significantly influence the apparent digestibility of organic matter and crude nutrients. Concentration of
acetate of rumen liquid was decreased (16 or 36) and that of
propionate was increased (25 or 50 mmoles per mol) when 200 or 500 mg
avoparcin per animal and day were added.
Acetate:
propionate ratio decreased from 4.2 to 3.5 and 3.1:1.
Avoparcin did not influence feed intake, enhanced daily
weight gain (37 to 174 g per animal and day) and improved feed efficiency (5 to 26%).
Salt lick stones with
avoparcin increased
weight gain (58 and 96 g per animal and day). Slaughtering results and body composition of bulls were not influenced by
avoparcin. Daily retention of
protein, fat and energy was significantly increased (16 to 18%; P less than 0.05) when
avoparcin was supplemented.