Research note: does compensatory growth occur following withdrawal of salinomycin from the diet of broilers?

The influence of withdrawal time on the performance of broiler chickens fed semduramicin

Three 49-d experiments, with a total of 6,528 male broiler chicks in floor pens, were conducted to test the hypothesis that Semduramicin feeding-time affects the body weight gain, feed consumption, and feed conversion ratio of broilers. Semduramicin ionophore was added to corn and soybean meal-based diets at the recommended level, 25 mg/kg for 0,34,39, or 42 d. Thus, three withdrawal times were employed (7, 10, and 15 d) during each experiment. Significant differences among experiments were observed for body weight gain, feed intake, and feed conversion ratio, but no significant differences due to Semduramicin were noted in body weight or feed intake. There was only one treatment by experiment interaction found for 0-to-34-d feed intake (P = 0.028), but it was not evident for 0 to 39 d (P = 0.818) or any other times. Feeding Semduramicin with a 10- or 15-d withdrawal period resulted in an improvement in feed conversion of about 0.04 units.

Final-week performance of straight-run broilers as affected by early coccidiostat withdrawal followed by increased dietary salt

Three experiments were conducted to evaluate elevated dietary NaCl levels as a means of offsetting industry-observed reductions of growth, feed intake, and feed efficiency associated with early (35-d) coccidiostat withdrawal. In the first experiment, monensin (100 ppm) was withdrawn and dietary salt levels of 0.33, 0.48, 0.63, 0.78, or 0.93% provided from 35 to 42 d of age. Experiments 2 and 3 involved lasalocid (110 ppm) withdrawal and slat amounts of 0.33, 0.53, 0.73, or 0.93%. In all studies, a positive control of 0.33% salt and the coccidiostat was also given. Monensin withdrawal reduced body weight gain, which was not overcome by slat addition. Feed efficiency during the 1-wk period was improved to the level of the group receiving continued medication by salt amounts of 0.78% or above. In contrast to industry field observations, removal of lasalocid did not reduce body weight gain, feed intake, or water consumption, and elevation of salt levels resulted in no consistent improvements of weight gain, feed intake, or feed conversion. Water intake increased proportionally as salt concentration increased. Elevated salt levels do not appear to be a reliable means of offsetting reduced performance related to early coccidiostat withdrawal, nor were such performance problems demonstrable for lasalocid in these trials.