Influence of mycotoxin binders on the oral bioavailability of tylosin, doxycycline, diclazuril, and salinomycin in fed broiler chickens.

The presence of mycotoxins in broiler feed can have deleterious effects on the wellbeing of the animals and their performance. Mycotoxin binders are feed additives that aim to adsorb mycotoxins in the intestinal tract and thereby prevent the oral absorption of the mycotoxin. The simultaneous administration of coccidiostats and/or antimicrobials with mycotoxin binders might lead to a reduced oral bioavailability of these veterinary medicinal products. This paper describes the influence of 3 mycotoxin binders (i.e., clay 1 containing montmorillonite, mica, and feldspars; clay 2 containing montmorillonite and quartz; and yeast 1 being a modified glucomannan fraction of inactivated yeast cells) and activated carbon on the oral bioavailability and pharmacokinetic parameters of the antimicrobials doxycycline and tylosin, and the coccidiostats diclazuril and salinomycin. A feeding study with 40 15 day-old broilers was performed evaluating the effects of long-term feeding 2 g mycotoxin binder/kg of feed. The birds were randomly divided into 5 groups of 8 birds each, i.e., a control group receiving no binder and 4 test groups receiving either clay 1, clay 2, yeast 1, or activated carbon mixed in the feed. After 15 d of feeding, both the control and each test group were administered doxycycline, tylosin, diclazuril, and salinomycin, consecutively, respecting a wash-out period of 2 to 3 d between each administration. The 4 medicinal products were dosed using a single bolus administration directly in the crop. After each bolus administration, blood was collected for plasma analysis and calculation of the main pharmacokinetic parameters and relative oral bioavailability (F = area under the plasma concentration-time curve (AUC0-8 h) in the test groups/AUC0-8 h in the control group)*100). No effects were observed of any of the mycotoxin binders on the relative oral bioavailability of the coccidiostats (i.e., F between 82 and 101% and 79 and 93% for diclazuril and salinomycin, respectively). Also, no significant effects could be noticed of any of the mycotoxin binders on the relative oral bioavailability of the antimicrobials doxycycline and tylosin (i.e., F between 67 and 83% and between 43 and 104%, respectively).