Anticoccidial Efficacy Research Articles

Anticoccidial Efficacy of Semduramicin in Battery Studies with Laboratory Isolates of Coccidia

The anticoccidial activity of semduramicin against laboratory isolates of five species of poultry Eimeria was investigated. In laboratory scale battery trials, semduramicin at 20 to 30 ppm demonstrated broad-spectrum anticoccidial efficacy equivalent to salinomycin at 60 ppm. Also, semduramicin at 25 ppm was fed to uninfected cockerels in batteries for 21 days, and growth rate and feed efficiency were found to be equivalent to birds fed salinomycin at 60 ppm. Semduramicin was well tolerated when coadministered with tiamulin. Semduramicin demonstrated the same activity whether produced by semisynthesis or by direct fermentation.

Anticoccidial Efficacy of Diclazuril against Recent Field Isolates of Eimeria from Turkey Farms in the United States

In a series of laboratory tests, diclazuril was evaluated for efficacy against Eimeria adenoeides, E. meleagrimitis, E. gallopavonis, and a mixture of the three species. Four isolates of each of the species were tested. When given at 0.5, 1.0, and 1.5 ppm in the feed, diclazuril was highly efficacious against all three species and against mixtures of the three, as judged by protection against mortality from coccidiosis, reduction in droppings scores, and improvement of weight gains compared with unmedicated controls. When diclazuril was given at 1.0 ppm, the improvement in droppings scores and weight gains was better than when 0.5 ppm of diclazuril was given. Increasing the dosage to 1.5 ppm did not appear to offer any consistent or significant improvement over 1.0 ppm.

A Comparison of Three Continuous and Four Shuttle Anticoccidial Programs

Continuous programs of a combination of narasin (40 ppm) and nicarbazin (40 ppm) (NaNi), narasin at levels of 60 and 70 ppm, and a 2 by 2 factorial shuttle design (NaNi or nicarbazin at 125 ppm, each for 27 or 28 days, followed by narasin at 60 or 70 ppm to termination), were compared with unmedicated controls for their anticoccidial efficacy and growth performance in nine broiler trials conducted in seven countries outside the United States. Cecal coccidial lesions were reduced only by treatments that incorporated nicarbazin either at the 40-ppm level in NaNi or at 125 ppm, whereas total intestinal lesion scores were reduced by all the anticoccidial programs tested. At Day 28, the three treatments containing NaNi and the treatment containing narasin at 60 ppm significantly improved weight gain and feed efficiencies over the two treatments containing nicarbazin at 125 ppm and the unmedicated controls.At termination all the anticoccidial programs significantly decreased the mortality rate and improved bird weights and feed efficiencies. Birds on the treatments containing NaNi either in the two shuttle programs or in the continuous program were significantly heavier than those on the two treatments containing nicarbazin at 125 ppm in shuttle programs.

Anticoccidial Efficacy of Diclazuril against Recent Field Isolates of Eimeria from Commercial Poultry Farms

The anticoccidial efficacy of diclazuril, a novel anticoccidial agent, was titrated in laboratory experiments using recent field isolates of Eimeria. Fifty tests were conducted with six individual species isolates, and seven tests were done with a mixture of the six species. Results were based on intestinal lesion scores at necropsy, droppings scores, and weight gain. Diclazuril at 0.5 ppm was almost completely effective against E. tenella, E. acervulina, and E. mitis. Prevention of E. brunetti was better at 1.0 ppm than at 0.5 ppm. In birds infected with E. mitis. Prevention of E. brunetti was better at 1.0 ppm than at 0.5 ppm. In birds infected with E. maxima, diclazuril at 0.5-1.5 ppm significantly reduced lesion scores and droppings scores and improved weight gain, although lesions were higher than with other species. Oocyst shedding by E. maxima was almost completely prevented by 0.5-1.5 ppm. Lesion scores and droppings scores caused by E. necatrix or mixed infections were greatly reduced by 0.5 ppm of diclazuril, but 1.0 ppm was necessary to obtain full protection of weight gain. Results suggest that 1.0 ppm of diclazuril best prevents coccidiosis caused by six species of coccidia in chickens.

Anticoccidial Efficacy of Diclazuril in Broilers under Simulated Natural Conditions in Floor Pens

Anticoccidial efficacy of diclazuril given for 42 to 49 days of age was evaluated in broiler chickens. Mortality from coccidiosis in unmedicated controls averaged 12.90% for six experiments. Treatment with diclazuril at 0.5, 1.0, and 1.5 ppm reduced coccidiosis mortality to 1.41%, 0.85%, or 0.63%, respectively, and reduced average total lesion scores by 78%, 81% or 82%, respectively. The final live weight and feed conversion at 49 days of age was significantly improved by treatment with diclazuril at all levels. Comparisons in some trials suggested that 1.0 ppm of diclazuril was equal or superior to the other anticoccidial drugs. There was no evidence that diclazuril harmed performance, even when given at 1.5 ppm.

Research Note: Anticoccidial Effect of Monensin Against Eimeria mitis and Eimeria dispersa

Four chick and five poult trials were conducted in order to investigate the anticoccidial efficacy of monensin against Eimeria mitis in chickens and Eimeria dispersa in turkeys. The chicks were fed a basal diet with either 0 or 100 ppm of monensin. The poults were fed a basal diet with either 0 or 60 ppm of monensin. Two days after the initiation of each experiment, the chicks and poults were crop-intubated with oocysts of E. mitis and E. dispersa, respectively. A group was also included that was not infected and not medicated. Growth and feed intake were recorded. At 6 or 7 days postinoculation, the birds were killed by cervical dislocation and were scored for the incidence and severity of intestinal abnormalities. The Eimeria mitis infection reduced (P<.01) gain and the feed:gain ratio, compared with uninfected birds; the E. dispersa infection only reduced (P<.05) gain. Although well-defined, discrete lesions were not observed, marked intestinal abnormalities were noted in birds infected with either E. mitis or E. dispersa. Also, the infected, unmedicated birds had increased (P<.01) intestinal scores compared with uninfected birds or those with infection but treated with monensin. Monensin eliminated the reduction in gain and feed efficiency seen in the infected birds. The infected birds fed monensin had intestinal scores, gain, and feed:gain ratios similar (P>.10) to those for the birds that were not infected and that did not receive medication.

Anticoccidial efficacy of diclazuril in pheasants.

Diclazuril, a new anticoccidial drug, was tested in young pheasants artificially infected with the three most common pathogenic species of Eimeria, E colchici, E duodenalis and E phasiani. In two replicate experiments each with 40 birds the mortalities in the infected controls were 50 and 25 per cent. Diclazuril was administered in the feed at dose levels of 1, 2 and 4 ppm from the day before the inoculation of coccidia until the end of the test on day 6 after infection. The 1 ppm dose failed to inhibit the development of the parasite completely, as was shown by a reduction of the weight gain of the birds and the output of a small number of oocysts. Diclazuril at 2 or 4 ppm adequately controlled the infection, with weight gains similar to those of the uninfected controls. At all dose levels, mortality, intestinal lesions and diarrhoea were prevented.

Potentiation of the anticoccidial effect of salinomycin with dihydroquinoline‐type antioxidants

The potentiating efficacy was determined on day 8 after infection with Eimeria tenella on the basis of oocyst counts and gross caecal lesions. The prototype of dihydroquinoline-type antioxidants (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) had no potentiating effect. When two molecules of the prototype were linked with an alkyl group (methylidene, ethylidene, or propylidene), the anticoccidial efficacy of salinomycin was increased such that a dose of 15 mg/kg was as effective as the standard 60 mg/kg given alone. The potentiating effect was lost if the molecule were acetylated or sulphonated. A similar potentiating effect was also demonstrable for monensin but was lacking for lasalocid.

Efficacy of diclazuril in the control of intestinal coccidiosis in rabbits

The anticoccidial efficacy of diclazuril was studied in rabbits artificially infected with Eimeria flavescens, Eimeria intestinalis, Eimeria magna and Eimeria perforans. Continuous administration at 1 and 2 ppm in pelleted feed proved to be highly efficacious in controlling oocyst output and faecal scores. The weight gain was comparable and the feed efficiency slightly improved compared with the non-infected, non-medicated controls, and clinical signs were fully prevented. Medication of rabbits at 0.5 ppm also provided a significant improvement in all parameters compared with the infected, non-medicated controls. In order to obtain 100% effectiveness in the control of intestinal coccidiosis in rabbits, continuous medication at 1 ppm is recommended.

Anticoccidial Efficacy of Narasin in Floor Pen Trials

Narasin is effective against all species of chicken coccidia when tested in short-term battery cage experiments. The efficacy of narasin at concentrations of 20, 40, 60, 80, and 100 ppm was evaluated in ten floor pen trials in which commercial broiler production conditions were simulated. To provide intentional exposure to different levels of coccidia challenge, the litter of some pens was seeded with oocysts of each of the pathogenic species of chicken coccidia, whereas some pens were left nonseeded. Weight gain, feed efficiency, and lesion score data from the ten trials were analyzed as one randomized block experiment.Medication with narasin resulted in a significant reduction in lesion scores and significant improvement in weight gain and feed:gain ratios when compared with scores and gain of nonmedicated controls for both seeded and nonseeded pens. Each increase in narasin concentration up to 100 ppm for the seeded pens and up to 80 ppm for the nonseeded pens resulted in a significant reduction in cecal lesion scores. Although maximum weight gain in the seeded pens was obtained with 40 ppm narasin, concentrations ≥60 ppm narasin were significantly better than the 40 ppm concentration in improving feed:gain ratios.These results confirm the effectiveness of narasin in controlling coccidiosis in broilers exposed to oocysts in the litter of floor pens. Furthermore, a clear relationship between the response to narasin and the level of oocyst challenge was demonstrated.

Anticoccidial Efficacy of Narasin in Battery Cage Trials

Narasin is a polyether monocarboxylic acid antibiotic produced by Streptomyces aureofaciens. An extensive series of battery cage trials was conducted to evaluate the efficacy of narasin against recent field isolates of the pathogenic species of chicken coccidia.Statistical analyses of the results of these studies revealed that each successive increase in the concentration of narasin produced a significant reduction in the severity of cecal and intestinal lesions when compared with those in infected nonmedicated controls. Increasing the concentration of narasin also produced significant improvements in weight gain and feed efficiency when compared to gain and feed efficiency of infected nonmedicated controls. Maximum weight gain of birds infected with Eimeria tenella alone was obtained at a narasin concentration of 60 ppm, but birds infected with E. tenella plus intestinal species of coccidia, when medicated with 80 ppm narasin had weight gains significantly greater than those of birds medicated with 60 ppm narasin. Weight gain improvement decreased at narasin concentrations ≥100 ppm. Results of these studies confirm the effectiveness of narasin in controlling coccidial infections produced by recent field isolates of the pathogenic species of chicken coccidia.

Anticoccidial Efficacy of Halofuginone in Turkeys Reared to Market Weight

Floor-pen studies were conducted in three geographic locations to study the efficacy of halofuginone (3.0 ppm in feed) against important species of coccidia in turkeys. Severe coccidiosis exposure was obtained in studies in Georgia and Colorado and mild coccidiosis in Wisconsin. Coccidiosis caused by contamination of the feed with oocysts of Eimeria adenoeides, E. meleagrimitis, and E. gallopavonis was almost completely controlled by halofuginone at 3 ppm, even though intestinal lesion scores and weight loss were high in two studies. Halofuginone was also highly effective in preventing buildup of infection in pens contaminated by indirect means (movement by caretakers through the pens, etc.). Weight gains and feed conversion were best in poults receiving halofuginone, whether directly or indirectly exposed. There was no evidence that halofuginone caused any untoward reactions in the poults, even though the drug was fed until turkeys reached market weight.

Antiparasitic activity of natural and semisynthetic monensin urethanes.

A total of 17 monensin urethanes, including two naturally produced phenethylurethanes (Streptomyces sp.), were evaluated for antiparasitic activity. All of the compounds had the characteristic properties of the polyether antibiotics including their ability to transport cations across membranes. Several of the semisynthetic derivatives demonstrated in vitro and in vivo anticoccidial activity in chickens. In vitro activity was shown utilizing chick kidney cell culture experimental procedures in which several of the semisynthetic antibiotics were active at 1 ppm or less. Derivatives having anticoccidial efficacy exhibited activity in vitro against Treponema hyodysenteriae, the causative agent of swine dysentery. Mice previously treated with specific semisynthetic urethanes survived a severe Plasmodium berghei challenge indicative of antimalarial properties as well. Specific biological activity could be correlated with structural relationships of the semisynthetic urethanes.

Anticoccidial Efficacy of Salinomycin (AHR-3096C) and Compatability with Roxarsone in Floor-Pen Experiments with Broilers

Five experiments were conducted to test the anticoccidial efficacy of salinomycin (AHR-3096C, A. H. Robins) at 66 ppm and its compatibility with roxarsone (50 ppm) under floor-pen conditions. Monensin (100, 121 ppm), lasalocid (75, 125 ppm), and shuttle programs of salino-mycin-monensin (66/100 ppm) or monensin-salinomycin (100/66 ppm) were included for comparison. Coccidiosis exposure was provided by using the infected seeder bird technique.Salinomycin reduced the lesion scores significantly and improved the body weight and feed conversion in all the trials as compared to unmedicated groups. All three ionophores effectively reduced the lesion scores. Birds treated with salinomycin-monensin shuttle programs had lesion scores, body weight, and feed conversion that were not significantly different from the salinoniycin treated birds, suggesting tha t this shuttle program could be used satisfactorily for control of coccidiosis. Lesion scores, body weight, and feed conversion data of the 4th and 5th trials suggested that the anticoccidial activity of salinomycin and roxarsone are additive. There was evidence of compensatory growth after withdrawal of salinomycin and monensin but not with lasalocid.

Influence of Anticoccidial Drugs on Losses of Broiler Chickens from Heat Stress and Coccidiosis

A floor-pen experiment conducted to study the anticoccidial efficacy of a number of drugs coincided with prolonged periods of hot weather and provided a good opportunity to study the interactions of anticoccidial drugs and environmental temperature. Six replicates of 60 day-old male chicks were fed one of the experimental diets for 48 days followed by a 5-day withdrawal period. The treatments consisted of unmedicated, salinomycin (60 ppm), monensin (100 ppm), arprinocid (60 ppm), halofuginone (3 ppm), amprolium/ethopabate (125/4 ppm), nicarbazin (12 5 ppm), and clopidol (125 ppm). Coccidiosis exposure was produced by mixing the suspensions of oocysts with the feed.Eleven heat related mortality episodes were recorded in the period of the experiment. All the mortality peaks were recorded at environmental temperatures at or above 37.8 C and relative humidity of 80 t o 98%. Heat stress caused an excessive mortality in nicarbazin treated birds at an early age (18 to 29 days of age), while heat related mortality was low at this age with other drug treatments. Total heat related mortality with nicarbazin treated birds was significantly higher (59.2%) than the other treatments (8 to 18.6%).In order to investigate further the interaction of environmental temperature and nicarbazin, two battery trials were conducted in controlled environmental rooms. No heat stress mortality was recorded in the period of the first trial when nicarbazin treated birds were exposed to a constant environmental temperature of 32.2 C; however, their performance was affected. The results of the second trial showed that when nicarbazin treated birds were exposed to a constant environmental temperature of 37.8 C they suffered more severely from the heat stress than the unmedicated group in a short period of time. The results of these experiments confirmed that an interaction exists between high environmental temperatures and the anticoccidial drug nicarbazin.

Compatibility and Anticoccidial Activity of Lasalocid in Combination with Roxarsone and Antibiotics against Eimeria Mixed Infection in Chicks

Lasalocid at the concentration of .0075% (68 g/ton) with and without roxarsone 45.4 g/ton was fed in combination with the growth promotants bacitracin methylene disalicylate 200 g/ton, bambermycins 2 g/ton, lincomycin 4 g/ton, nosiheptide 2.5 g/ton, zinc bacitracin 200 g/ton, and virginiamycin 20 g/ton exhibited a high degree of anticoccidial activity against mixed Eimeria infection in chickens in 9 day challenged battery trials. In these short term challenge trials chicks fed lasalocid, and the lasalocid growth promotant combinations, performed significantly better (P<.05) for growth and anticoccidial efficacy than those fed the growth promotants alone, and the infected, unmedicated controls. In almost all instances, the lasalocid-roxarsone-antibiotic combinations allowed for numerical increases in gains, improvement in feed conversion, and numerical decreases in lesions (in some cases, statistically significant (P<.05) over chicks fed lasalocid alone and/or the lasalocid antibiotic combination. The growth promotants did not interfere with the anticoccidial activity of lasalocid.The growth promotants fed alone exhibited no anticoccidial activity. However, when roxarsone was combined with the antibiotics, the combination resulted in numerically improved performance, reduced mortality, and in most instances, statistically significant decreases in lesions (P<.05) over the infected, unmedicated control.

Anticoccidial Efficacy of a New Polyether Antibiotic, Salinomycin, in Comparison to Monensin and Lasalocid in Battery Trials

Broiler chicks were given salinomycin in the feed at levels of 30 and 60 ppm in battery trials to measure the efficacy against six major species of Eimeria. Comparisons to non-medicated chicks (controls) and chicks given monensin at 50 and 100 ppm or lasalocid at 37.5 and 75 ppm were made. Factors measured were the severity of coccidia lesions, mortality, and weight gain. The efficacy of salinomycin, monensin, and lasalocid in preventing lesions differed in many respects. The lesion control of salinomycin at 60 ppm was excellent against E. acervulina, E. mivati, E. necatrix, and E. tenella, and slightly reduced against E. maxima and E. brunetti. The lesion control of monensin at 100 ppm was excellent against E. mivati and E. necatrix, and slightly reduced against E. tenella, E. acervulina, E. maxima, and E. brunetti. The lesion control of lasalocid at 75 ppm was excellent against E. brunetti, slightly reduced against E. maxima, E. necatrix, and E. tenella, and lowest against E. acervulina. Based upon all measurements, salinomycin at 60 ppm was comparable or superior to monensin at 100 ppm and lasalocid at 75 ppm. At 30 ppm, salinomycin was more effective overall than monensin at 50 ppm or lasalocid at 37.5 ppm. The relative potency of each anticoccidial agent was clearly evident in these data.

Floor Pen Studies on the Anticoccidial Efficacy of Arprinocid in Turkeys

Arprinocid was tested against coccidiosis in turkeys reared in floor pens. Contamination of pens with Eimeria meleagrimitis, E. adenoeides, and E. gallopavonis was accomplished by the infected seeder bird technique. Performance improved with increasing levels of arprinocid through 120 ppm, but weight gains were depressed at 180 ppm. Lesion scores were significantly and progressively reduced by treatment with 60, 90, 120, and 180 ppm of arprinocid. Control of lesion scores and performance of birds treated with 120 ppm of arprinocid were comparable to the amprolium (125 ppm) treatment. In a separate experiment, the oocyst passage of E. meleagrimitis and of E. adenoeides was progressively reduced by increasing levels of arprinocid, and sporulation rate was decreased. Sporulation was not obtained in oocysts from birds fed arprinocid at 120 ppm or higher.

Battery Efficacy Studies with Arprinocid against Field Strains of Coccidia

Graded levels of 9-[2-chloro-6-fluorophenyl)methyl]-9H-purin-6-amine (arprinocid) ranging from 30 ppm to 90 ppm in the diet have been tested for anticoccidial efficacy in controlled battery experiments against 20 field isolates of coccidia. These isolates, representing five major species of Eimeria, were collected from various geographic locations and all but one were found to be resistant to one or more of the currently marketed products. Arprinocid prevented mortality, increased weight gains, and reduced or eliminated intestinal lesions and oocyst production. A level of 60 ppm arprinocid provided adequate control of all isolates and no evidence of cross resistance was observed between arprinocid and the marketed products tested. On the basis of these studies, it is concluded that arprinocid at levels of 60 ppm to 70 ppm is effective in controlling coccidiosis in broilers, even that caused by isolates refractory to many of the marketed products.

Comparison of Anticoccidial Efficacy, Resistance and Tolerance of Narasin, Monensin and Lasalocid in Chicken Battery Trials

The anticoccidial efficacy, host tolerance, and projected resistance development of the three polyether antibiotics, monensin, narasin, and lasalocid were compared. The efficacy of narasin against different coccidial strains was found to parallel that of monensin in as much as strains which were refractory to monensin were also refractory to narasin. In contrast, lasalocid easily controlled some strains which were not well controlled by either narasin or monensin and failed to control one strain readily controlled by these two antibiotics.In growing chicks, lasalocid at the projected use level of 75 p.p.m. and narasin at an efficacious level of 100 p.p.m. were both better tolerated than monensin at the recommended use level of 121 p.p.m.The frequency of mutants resistant to each of these polyether compounds was found to be less than 8.6 × 10–9 per drug sensitive oocyst for one strain of Eimeria tenella. This corresponds to less than 0.036 and 0.148 as frequent as mutants of this strain resistant to glycarbylamide or to amquinate, respectively.