robenidine and Poultry-Diseases

Drug resistance is now recognised as a major cause of the failure of drugs to control coccidiosis in the fowl. In this article, biological, biochemical and genetic aspects of resistance in Eimeria are reviewed and some of the problems that may limit progress in understanding the nature of resistance in coccidia are discussed.

Topics: Animals; Chickens; Clopidol; Coccidiosis; Coccidiostats; Drug Resistance; Eimeria; Imidazoles; Poultry Diseases; Robenidine; Turkeys

New anticoccidials continue to be introduced to the poultry industry on an average of about one every 2 years. Revised requirements have increased costs of discovery, development, and approval by the Food and Drug Administration to several million dollars for each product. Gross sales of anticoccidials are now estimated to be in excess of $30,000,000 annually. Anticoccidials are almost universally used in starter rations for meat-type birds being raised under floor-pen management. Protection is more important with these fast-growing birds than with egg-producing types where immunity and cage layer management modify demands for anticoccidials. Coccidiosis mortality has generally been eliminated by all 25 approved anticoccidials if properly used. Selection of specific anticoccidials is based on the ability of the anticoccidial to: (1) improve weights and (2) feed conversion, and (3) to suppress development of lesions. Costs of the product may influence decisions on which one to use. With some anticoccidials the rapid emergence of drug resistant strains has been the biggest problem. "Switching" among the 13 classes of anticoccidials and the so-called "shuttle program" are common methods used to avoid development of resistance. Preventive medication will probably continue to constitute the major method of coccidiosis control with meat-type poultry if attempts to develop economic cage-type management do not supplant current litter and floor-pen management. Immunity acquired through incidental or planned immunization is more important in control of coccidiosis with layer and breeder flocks raised in floor-pens. Some progress in development of avirulent immunogenic strains of different species of coccidia has been reported and further research efforts in this direction should be encouraged.

Topics: Administration, Oral; Animal Feed; Animals; Antiprotozoal Agents; Chickens; Coccidiosis; Costs and Cost Analysis; Drug Resistance; Eimeria; Immunization; Monensin; Poultry Diseases; Robenidine; Time Factors; United States; United States Food and Drug Administration

A floor pen trial was carried out on broilers in 1975 to compare the anticoccidial efficacy of monensin1), 3,5 dinitro-o-toluamide2), clopidol3), amprolium + ethopabacte4), amprolium + ethopabate + sulfaquinoxaline + pyrimethamine5) and robenidine6) in the presence of untreated controls. 4,200 Hybro chicks were distributed over twenty-eight pens, each initially housing 150 birds. Four pen replicates were allocated to each of the seven treatments. With the exception of robenidine, all agents used resulted in a statistically significant (P less than or equal to 0,05) gain in final weight compared with the untreated controls. The feed conversion rate showed significant (P less than or equal to 0,05) improvement in the groups treated with monensin, robenidine, amprolium + ethopabate.

Topics: Amprolium; Animals; Chickens; Clinical Trials as Topic; Clopidol; Coccidiosis; Coccidiostats; Ethopabate; Monensin; Poultry Diseases; Pyrimethamine; Robenidine; Sulfaquinoxaline

Ten Eimeria field isolates from North Germany were studied in battery tests for sensitivity to selected anticoccidials. A high percentage of the Eimeria field isolates (9 out of 10) showed resistance to anticoccidials, mostly multiple resistance. Partial or complete resistance to maduramicin was found in 7 field isolates, to monensin in 6, to salinomycin in 5, to nicarbazin in 8, to halofuginone in 7, to robenidine and toltrazuril in 1, and to diclazuril in 2 field isolates. Multiple resistance had developed in 7 of the 10 isolates. Cross-resistance between maduramicin, monensin, and salinomycin occurred in 5 Eimeria isolates. One isolate showed cross-resistance between diclazuril and toltrazuril. From the resistant isolates 15 pure E. acerculina and 5 pure E. brunetti strains were obtained by single oocyst infections. Seven of the E. acerculina and 4 of the E. brunetti strains showed resistance or partial resistance that was also present in the original isolate. Ten of 11 resistant strains were multiply resistant.

Topics: Animals; Chickens; Coccidiosis; Coccidiostats; Drug Resistance; Drug Resistance, Multiple; Eimeria; Germany; Lactones; Male; Monensin; Nicarbazin; Nitriles; Piperidines; Poultry Diseases; Pyrans; Quinazolines; Quinazolinones; Robenidine; Triazines

A floor-pen trial was conducted to investigate the effects of different shuttle programs upon the growth of broilers to 8 wk of age. Nicarbazin, halofuginone, and robenidine, when included in the starter feed for 3 wk, were effective in preventing lesions due to Eimeria. The effects of medication upon performance were apparent, medicated groups gaining more weight by 6 wk and having a lower feed conversion at 6, 7, and 8 wk than the unmedicated controls. There were no significant differences in body weight at 6, 7, or 8 wk or feed conversion at 6 or 7 wk among the medicated groups, whether medication was withdrawn for 7 or 14 days. A decrease in the number of small and medium oocysts in the litter was observed as the trial progressed. Few large oocysts (Eimeria maxima) were seen in the medicated groups. Numbers of oocysts did not increase following withdrawal of medication. Birds from all medicated groups were challenged at 6 wk with oocysts of Eimeria acervulina, Eimeria maxima, or Eimeria tenella. Weight gains were similar to that of the unchallenged controls, indicating that they had acquired immunity to these species of Eimeria.

Topics: Animals; Body Weight; Chickens; Coccidiosis; Coccidiostats; Diet; Eimeria; Feces; Immunity; Male; Nicarbazin; Parasite Egg Count; Piperidines; Poultry Diseases; Quinazolines; Quinazolinones; Robenidine

Thirty isolates of Eimeria tenella obtained from broiler and breeder farms were examined for their sensitivity to anticoccidial drugs. All were sensitive to robenidine, 28 were sensitive to methyl benzoquate, 25 to clopidol and 21 to nicarbazin. Most isolates were resistant or partly resistant to amprolium and dinitolmide.

Topics: Amprolium; Animals; Chickens; Clopidol; Coccidiosis; Coccidiostats; Dinitolmide; Drug Resistance; Eimeria; Nicarbazin; Poultry Diseases; Quinolones; Robenidine

Topics: Animals; Chickens; Clopidol; Coccidiosis; Guanidines; Poultry; Poultry Diseases; Pyridines; Robenidine

Topics: Animals; Coccidiosis; Digestive System; Eimeria; Immunity; Poultry; Poultry Diseases; Robenidine; Sulfaquinoxaline

Tests for resistance to a recently introduced anticoccidial drug, robenidine, were performed on a strain of Eimeria tenella recovered from broiler chickens infected with acute cecal coccidiosis. The strain was identified previously and again confirmed by the timing of mortality of the infected chickens (five to six days postinfection), the appearance of lesions and parasites in ceca only, and the measurements (21.6 +/- 1.9 micron X 19.8 +/- 2.4 micron) of the oocysts. The tests showed that the strain of E. tenella could establish infections in chickens medicated with fourfold the recommended level of robenidine in feed but no oocysts could be recovered from the feces of infected chickens when the level of drug was increased to eightfold. The decrease in mortality, in the severity of lesions and oocyst output and the increase in the average weight gain of infected chickens followed closely the increase in the level of robenidine in feed. In contrast, no infections were found in chickens infected with a sensitive strain of E. tenella and maintained on feed mixed with the recommended level of robenidine. This and other findings discussed here show that resistance to robenidine is developing in coccidia commonly found in broiler houses.

Topics: Animals; Chickens; Coccidiosis; Drug Resistance, Microbial; Eimeria; Guanidines; Poultry Diseases; Robenidine

The development of resistance by the Houghton strain (H) of E. tenella to robenidine has been studied in the laboratory, by serially passaging the strain in chickens fed increasing concentrations of drug. Resistance to robenidine developed more readily in experiments using larger numbers of birds with higher numbers of oocysts in the inoculum. Both these factors increased the parasite population and increased the chance of selecting parasites resistant to the drug. E. tenella (H) was made resistant to 264 ppm robenidine and showed no cross-resistance to other anticoccidial agents. Resistance arose in a series of 'steps' as the concentration of drug was increased. E. tenella (H) was continuously passaged at concentrations ranging from 2 to 33 ppm of robenidine. After 16 passages, lines passaged at 2,4 and 8 ppm were not resistant to 33 ppm robenidine, suggesting that the degree of resistance developed was dependent upon the drug selection pressure.

Topics: Animals; Chickens; Coccidiosis; Coccidiostats; Drug Resistance; Eimeria; Feces; Guanidines; Poultry Diseases; Robenidine

Features of the anticoccidial activity of nicarbazin, amprolium, zoalene, sulphadimidine, diaveridine, Darvisul, spiramycin, chloramphenicol and oxytetracycline have been re-investigated both in vivo and in cell culture using Eimeria tenella. Of the drugs studied, only spiramycin was appreciably coccidiocidal, although nicarbazin and amprolium showed possibly slower coccidiocidal activity. In order to show activity against a particular stage in the life-cycle, higher concentrations of drug than those usually recommended for field usage had in most cases to be used. Under these conditions, parasites were usually inhibited as multinucleate 1st generation schizonts. With delayed medication, effects against 2nd generation parasites were in most cases found, and in many cases, although the parasites never matured to give viable merozoites, the large degenerating forms produced were able to cause extensive tissue destruction and haemorrhage. Methodology in this type of study is discussed in relation to more active and more recent anticoccidials, and some further experiments with robenidine reported.

Topics: Amprolium; Animals; Cells, Cultured; Chickens; Chloramphenicol; Coccidiosis; Coccidiostats; Dinitolmide; Eimeria; Leucomycins; Nicarbazin; Oxytetracycline; Poultry Diseases; Robenidine; Sulfaquinoxaline

Topics: Amprolium; Animals; Chickens; Clopidol; Coccidiosis; Coccidiostats; Drug Evaluation, Preclinical; Hydroxyquinolines; Poultry Diseases; Quinolines; Robenidine; Sulfaquinoxaline

Topics: Animals; Cecum; Chick Embryo; Chickens; Cytoplasmic Granules; Eimeria; Endoplasmic Reticulum; Golgi Apparatus; Guanidines; Lipids; Lysosomes; Microscopy, Electron; Poultry Diseases; Robenidine; Time Factors; Vacuoles