Feed restriction as an alternative to the use of antibiotics in non controlled environment farms

The effect of antimicrobials and feed restriction (as an alternative to the use of the formers)  on production performance of growing rabbits reared in a non-controlled environment was estimated. A total of 987 young rabbits from a three way cross were randomly distributed into groups of 8 individuals, which were assigned to one of the following feeding strategies from 35 to 63 days of life: ad libitum feeding with medicated feed (antibiotics and a coccidiostatic; AdLibMed), ad libitum feeding with no medicated feed (AdLibNoMed), restricted feeding with medicated feed (RestrMed) and restricted feeding with no medicated feed (RestrNoMed). All groups were fed ad libitum with no medicated feed from 63 to 70 d. Feed offered to restricted animals was calculated weekly as 80% the feed intake of the batch-mates fed ad libitum the week before, increased by 10% to account for the increase in consumption with age. Feed restriction finally applied was on average 84.2%. Ad libitum feeding with no medicated feed led to lower average daily gain and relevantly higher but not significantly different mortality with respect to AdLibMed  (-1.29 g/d, p-value=0.03; +2.98%, p-value=0.28). Feed restriction did not improve performance, as average daily gain was lower than when animals were fed ad libitum, and mortality rate did not improved (-3.44 g/d, p-value<0.01; -0.52%, p-value=0.93; RestrNoMed vs. AdLibNoMed). These results are probably due to the range of variation of actual feed restriction along the trial (72 to 100% of ad libitum feed intake) and the low mortality rate in the overall trial (7.62% for ad libitum, and 6.12% for restriction). None of the treatments had effect on feed efficiency. Therefore, feed restriction might not be the best alternative to the production without antibiotics when feed intake is highly conditioned by environmental changes and mortality is low, and the use of other alternatives to avoid a decrease in daily gain is required.

Key words: antibiotics, environmental control, feed restriction, mortality, performance, rabbits.