SUMMARY The goal of an anticoccidial program either anticoccidial drugs or live coccidia vaccines is to control the severity of coccidiosis thus maximizing performance. Anticoccidial drugs have been successfully used for over 80 years. However, extensive usage and the limited number of approved drugs has led to some degree of resistance being developed to all drugs. Three independent battery trials were conducted to evaluate the anticoccidial drug sensitivity (AST) of species/strains of Eimeria within three commercial coccidia vaccines. The vaccines used for these studies were Immucox 3 ® (broiler vaccine) (IM3), Immucox 5 ® (broiler breeder vaccine) (IM5), and Immucox T ® (turkey vaccine) (IMT). Each trial utilized a randomized block design with 6 replications of each treatment. Blocks consisted of cage location within the battery; each cage contained 8 male Cobb 500 broilers (IM3 and IM5) or 8 male Hy-Line turkeys (IMT). Upon receipt from the hatchery, the non-coccidia vaccinated birds were placed into battery cages and colony raised on non-medicated feed. At 12 days of age (D0), birds were examined, healthy birds pooled, group weighed, allocated to treatment cages, and issued weighed treatment feeds. At the initiation of the trial (D0) and D8 (20 days of age) (IM3 and IM5) or D9 (21 days of age day (IMT), each cage of birds was group weighed. Birds had ad libitum access to feed and water. Feed intake was measured from D0 to D8 or D9. Basal non-medicated rations were formulated as a typical commercial broiler starter corn-soybean meal ration (22% protein, 3,000 kcal/kg metabolizable energy) or commercial turkey starter corn-soybean meal ration (28% protein, 3,020 kcal/kg metabolizable energy). Anticoccidial drugs were blended at commercial use levels with these basal rations. The treatments were as follows. IM3 :(1) Non-medicated non-challenged (NMNC); (2) Non-medicated challenged (NMC); challenged and medicated with (3) robenidine 33 ppm; (4) decoquinate 30 ppm; (5) clopidal 125 ppm; (6) zoalene 125 ppm; (7) diclazuril 1 ppm; (8) amprolium 125 ppm; (9) salinomycin 66 ppm; (10) narasin 39.6 ppm + nicarbazin 39.6 ppm ; and (11) narasin 74.25 ppm. IM5 used the same IM3 treatments1-11 plus (12) nicarbazin. IMT : 1) Non-medicated, non-challenged (NMNC); (2) Non-medicated, challenged (NMC); (3) lasalocid 79.2 ppm; (4) monensin 66 ppm; (5) amprolium 125 ppm; (6) zoalene 125 ppm; and (7) clopidal125 ppm. The challenge for each vaccine was 100 X the commercial recommended dose given orally on D2 (14 days of age). For trials IM3 and IM5, on D8 (6 days post challenge) all chickens were coccidia lesion scored. IMT oocysts per gram and dropping scores were determined instead of lesion scores. Coccidia oocysts production (D7-9) was determined by counting number of oocysts per gram fecal material (OPG). On D8 (day 6 post inoculation), fecal material from all cages were visually numerically scored for degree of coccidiosis. For IM3 and IM5 vaccines, the results showed that all strains were highly sensitive to robendiene, decoquinate, clopidol, salinomycin, narasin, narasin + nicarbazin, and nicarbzin (IM5). Differences in anticoccidial drug efficacy also influences interpretation of results. All strains were sensitive to diclazuril, zoalene, and amprolium but coccidiosis control was not as pronounced due to efficacy issues of the drugs. For turkey IMT vaccine, the results showed that all strains were highly sensitive to clopidol, zoalene, amprolium, lasalocid, and monensin. This information can serve as a foundation for the use of these coccidia vaccines in the restoration of coccidia sensitivity in the field.

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