Effect of diet supplementation with oxytetracycline combined or not with different feed-additives on fattening performance in the rabbit

Two trials were conducted in two different places with a 2 x 2 factorial experimental design, to evaluate, during the fattening period, the influence of the addition of oxytetracycline (200 ppm) alone or with live yeast (Saccharomyces cerevisiae, Sc 47, 10(6) CFU/g of feed) in the trial 1 or with flavophopholipol (4 ppm) in the trial 2. A total of 4 x 300 rabbits weaned at 30 days was employed for trial 1 and 4 x 108 32-days weaned rabbits for trial 2. Diets with oxytetracycline (OTC) were distributed during the first 4 weeks of the experiment and the others were employed during the whole period of the study: 49 day for trial 1 and 39 days for trial 2 or during the final part of the experiment. A digestibility study of the first trial feeds was performed with 4 cages of four rabbits per diet Mortality, growth rate and feed conversion ratio were not significantly different between control and experimental groups, whatever the trial. Nutrients digestibility was not modified by the addition of OTC and/or addition of live yeast. The average Digestibility coefficients were 64.5 - 72.2 and 23.8 for organic matter, nitrogen and crude fibre respectively. In both trials, the greater growth rate was observed for the Control group without any addition : 41.2 and 45.6 g/day for trials 1 and 2 respectively. In trial 2, a greater growth rate (+5.5% on average) was observed immediately after weaning with flavophospholipol addition, but this effect disappeared after.