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Anticoccidial Activity of Salinomycin in Floor-Pen Experiments with Broilers
Anticoccidial Activity of Salinomycin in Floor-Pen Experiments with Broilers HARRY D. DANFORTH 1 , MICHAEL D. RUFF 2 , W. MALCOLM REID 2 and JOYCE JOHNSON 2 'A. H. Robins Company, Research Laboratories, 1211 Sherwood Avenue, Richmond, Virginia 23220, and 2 Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication October 4, 1976)
Poultry Science 56:933-938, 1977 INTRODUCTION The fermentation product salinomycin ( A H R - 3 0 9 6 , A. H. Robins) has been shown in laboratory e x p e r i m e n t s t o be an effective anticoccidial agent against mixed and single species Eimeria infections in chickens (Danforth etal., 1977). However, these experiments give only limited d a t a o n t h e possible efficacy of this c o m p o u n d u n d e r commercial p o u l t r y conditions. Floor-pen e x p e r i m e n t s (Brewer and Kowalski, 1 9 7 0 ; Reid et al, 1969, 1975) provide broiler p r o d u c t i o n conditions similar t o those seen in t h e field, and are recognized as a reliable m e t h o d for predicting field perform a n c e of new anticoccidials. In two separate floor-pen experiments, t h e efficacy of salinomycin was compared with t h e reference anticoccidial monensin and u n m e d i ated infected controls. To test anticoccidial activity various techniques were e m p l o y e d t o insure severe t o mild exposure t o coccidiosis. MATERIALS AND METHODS In t w o e x p e r i m e n t s , 1,800 or 2,000-day broiler-type cockerel chicks (Cobb hybrids) were grown in 36 or 4 0 floor-pens (approximately 4.8 square meters) each containing 50 birds. T h e pen-floors were cleaned before t h e trial and covered with a p p r o x i m a t e l y 9 cm. of new pine shavings of litter. Each pen was subdivided into t w o parts with heavy paper
being laid over t h e back half of t h e pen t o prevent accidental exposure t o oocysts. During t h e starting period (10 days, E x p e r i m e n t 1; 21 days, Experiment 2) personnel were denied access to this p o r t i o n of t h e p e n . T h e principal birds were started here and later transferred t o t h e front half of t h e pen for oocyst e x p o s u r e (10 days, E x p e r i m e n t 1; 21 days, E x p e r i m e n t 2). T h e pen divider and paper covering t h e back part of t h e pen were removed o n e day after exposure. A basal diet of open formula broiler starter ration (Ruff et al., 1 9 7 6 ) was fed t h e first four weeks of t h e trial and a finisher formula was used during t h e last four weeks of t h e trial. Modified commercial broiler m a n a g e m e n t was followed in all pens for b o t h e x p e r i m e n t s . To provide exposure t o coccidiosis in different degrees of severity, different c o m b i n a tions of seeding t h e litter and starting t h e principal birds were used as follows: Experiment 1: Method 1. T h e principal birds w e r e started o n t h e floor in t h e back p o r t i o n of t h e pen. For oocysts exposure White Leghorn males were infected at t w o w e e k s of age and placed 5 days after infection (one day before principal birds arrived) in suspended cages on u n m e d i c a t e d feed where droppings could fall on t h e litter in t h e front p o r t i o n of t h e floor-pen. F o r each pen three seeder birds were inoculated with 10 X Coccivac D (containing eight species of Eimeria, E. acervulina, E.
933
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ABSTRACT The anticoccidial agent salinomycin (AHR-3096) was compared at various treatment levels (60 to 100 p.p.m.) in two experiments against unmedicated and either 100 or 121 p.p.m. monensin-medicated groups to evaluate its performance under floor-pen conditions. Various methods for the initial rearing of birds and coccidial exposure were employed to test the efficacy of salinomycin against severe, moderate, and mild coccidiosis. Salinomycin at all treatment levels showed definite anticoccidial activity resulting in improved weights, feed conversion ratios, lesion scores, and mortality compared with unmedicated controls. In pens with severe coccidiosis, this compound demonstrated a significant improvement in all parameters when compared with the corresponding unmedicated controls. Salinomycin-treated pens exposed to light coccidiosis usually had a numerical increase in the parameters over the unmedicated control groups. Statistical analysis of overall main effects on mortality, weight gain, and feed conversion ratio showed no significant differences between the activity of any level of salinomycin and monensin.
934
DANFORTH, RUFF, REID AND JOHNSON
Method 3. As a further precaution to prevent artificial exposure, the principal birds were maintained for ten days in wire-floored battery brooders located in the pens. These birds were then transferred to the litter contaminated from seeder-birds managed in the same manner as in Method 1. Method 3 has been designated "wire-seeders". Each of these three seeding methods was included to provide production data on three different medication regimens: 100 p.p.m. salinomycin, 121 p.p.m. monensin and unmedicated controls. A total of 36 pens were used with 4 pen replications for each of the 9 treatments. Experiment 2. All principal birds were raised for 21 days in the back portion of the divided floor-pen as in Method 1 above. Two methods of exposure were employed to test the protection of anticoccidials against different degrees of coccidiosis. Severe exposure ("direct seeding") was provided by using seeder birds as described above in Method 1. The seeder birds were inoculated on day 3 with either 10 X Coccivac D or two different field strain isolates containing E. tenella, E. acervulina, E. brunetti and E. maxima. Mild exposure ("indirect seeding") came from oocysts brought in accidentally by shoes, equipment, and dirt. Five pens randomly selected both from direct and indirect seeding groups were each placed on one of the following anticoccidial regimes: 60 p.p.m. salinomycin, 80 p.p.m.
salinomycin, 100 p.p.m. salinomycin, 100 p.p.m. monensin or unmedicated controls. Parameters used in both experiments to evaluate anticoccidial activity were: 1) coccidiosis mortality, 2) total mortality, 3) average weight of live birds at four and eight weeks, 4) feed conversion at four and eight weeks, and 5) average lesion scores. Four birds per pen per time were lesion scored (Johnson and Reid, 1970) at 18 and 28 days in Experiment 1, and 28 and 38 days in Experiment 2. These times corresponded to 9 and 19 days after exposure to oocysts (Experiment 1), and 7 and 17 days after exposure (Experiment 2). All data were submitted to an analysis of variance and Duncan's multiple range test (Duncan, 1955). Differences were recorded as significant whenever probability (P) was less than 0.05.
RESULTS Mortality and Severity of Coccidial Infection. Mortality from coccidiosis in the unmedicated pens was used as the primary criterion for judging severity of the coccidial exposure and subsequent infection. Based on this parameter, the floor-seeders and wire-seeders groups, Experiment 1, produced severe coccidiosis (17% and 24% mortality, respectively, Table 1). Moderate coccidiosis was found in the floorfecal seeding group, Experiment 1, and the direct seeding group, Experiment 2 (3% and 2% mortality, respectively, Tables 1 and 2). Mild coccidiosis (no mortality) occurred with indirect seeding, Experiment 2. All treatment levels of salinomycin and monensin medication either prevented or decreased coccidiosis-induced mortality when compared with the unmedicated controls (Experiments 1 and 2, Tables 1 and 2). No significant difference in mortality was seen between salinomycin and monensin. Weights. Salinomycin-medicated groups showed a significant increase in the average weight of live birds in all seeded pens when compared with the weight of unmedicated controls in both experiments (Tables 1 and 2). A numerical but not statistical increase in weight gain was seen with the 80 and 100 p.p.m. salinomycin in non-seeded pens (Experiment 2, Table 2). In Experiment 1, 100 p.p.m. salinoymcin produced a significantly higher average weight of live birds in the floor-seeder treatment at both four and eight weeks than did 121 p.p.m. monensin (Table 1). In all other
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brunetti, E. maxima, E. mitis, E. mivati, E. necatrix, E. praecox, and E. tenella). Three other birds were inoculated with a mixture of recent field isolates containing six species of Eimeria oocysts (E. acervulina, E. mivati, E. maxima, E. necatrix, E. brunetti, and E. tenella). Seeder birds were removed after 10 days. Moisture levels were increased under these seeder-bird cages to at least 30 percent. This method is hereafter identified as "floor-seeders". Method 2. Principal birds were raised on the floor as in Method 1. Litter in the front half of the pen was contaminated by spreading feces containing oocysts (approximately 50% sporulated). This fecal material had been collected between 6 to 10 days post-inoculation from 10 birds reared in batteries. Half of these birds were inoculated with 10 X Coccivac D and the remaining five were inoculated with the same field isolates used in Method 1. This method of exposure is designated as "floor-fecal seeding".
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treatments there were no statistical differences in weight gain between the salinomycin and monensin medicated pens. An analysis of main effects of salinomycin and monensin on weight gain showed no overall significant differences between the two medications. Feed Conversions. Feed conversions at eight weeks in Experiment 1 are expressed in two different columns because of the death of a number of birds from laryngotraceitis two days before termination of this trial (Table 1). The adjusted feed conversion column includes the weight of the birds which died from that disease. Birds medicated with either 100 p.p.m. salinomycin or monensin in this experiment had significantly lower feed conversion ratios than did the unmedicated control groups. The feed conversion at four and eight weeks in the 60 to 100 p.p.m. salinomycin-medicated seeded pens in Experiment 2 were significantly better than in the unmedicated seeded pens (Table 2). No significant difference in fourweek feed conversions was seen between nonseeded pens, either medicated or unmedicated. However, at eight weeks the medicated nonseeded pens did show a significantly lower feed conversion. At four weeks, feed conversion in the monensin-medicated, seeded pens was significantly better than in the 80 p.p.m. salinomycin-medicated pens. However, main effect analysis showed no overall significant differences in the effect of salinomycin and monensin on feed conversion ratios. Lesion Scores. Salinomycin-medicated birds in Experiments 1 and 2 had reduced lesions in the three areas of the intestine and the ceca when compared with unmedicated birds in the seeded pens (Figs. 1 and 2). There was no significant difference seen between the total lesion scores for either monensin or the three levels of salinomycin (60—100 p.p.m. In Experiment 1, the lesion score in the middle and lower intestinal areas was significantly lowered by salinomycin in the floorseeder and wire-seeder treatments. By 19 days after bird exposure, the lesion scores in the various areas had decreased to a level in the unmedicated controls where the effects of medication were not apparent in any one particular intestinal area. However, the total lesion score showed a significant reduction in the salinomycin and monensin groups when compared with the unmedicated controls (Fig. 1). In Experiment 2, a numerical decrease in
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935
DANFORTH, RUFF, REID AND JOHNSON
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FIG. 1. Effect of medication on intestinal lesion scores in broilers, Experiment 1. Total lesion scores within a time period not having a common letter are significantly different (P<0.05). 0 = unmedicated; S = 100 p.p.m. salinomycin; M = 121 p.p.m. monensin.
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MEDICATION
ANTICOCCIDIAL ACTIVITY OF SALINOMYCIN
937
TABLE 2. — Anticoccidial activity of salinomycin in floor pens (Experiment 2)1
Oocysts seeding
Treatment
Coccidiosisassociated mortality 4/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200
Average feed conversion
Average wt. gain in kg. 4 weeks
8 weeks
4 weeks
8 weeks
0.65lt> 0.716 a 0.714^ 0.711* 0.713* 0.699 a 0.717* 0.707a 0.717a 0.720a
1.836 c 1.950bc 2.094ab 2.102a 2.062ab 2.069 a b 2.055 a b 2.023 a b 2.086ab 2.118a
1.715a 1.632bc 1.66lbc 1.650bc 1.669 b 1.672b 1.634bc 1.654bc 1.624 c 1.67lb
2.227a 2.125b 2.049 c 2.056 c 2.033 c 2.025 c 2.044 c 2.025C 2.03 7C 2.044C
1
Means within a parameter not followed by a common superscript letter are significantly different (P<0.05).
2
+ = direct seeding (seeder birds); — = indirect seeding (no seeder birds).
lesions was seen in t h e seeded pens as t h e level of salinomycin medication increased. All nonseeded medicated pens showed significantly lower scores at seven days after oocysts e x p o sure when c o m p a r e d with t h e u n m e d i c a t e d non-seeded pens. Only t h e pens fed 8 0 p . p . m . salinomycin showed significantly lower total lesion scores t h a n t h e u n m e d i c a t e d pens at 17 days post-exposure. DISCUSSION Floor-pen e x p e r i m e n t s are recognized as a reliable testing t e c h n i q u e for predicting t h e field performance of new anticoccidial comp o u n d s (Reid, 1 9 7 1 ) . In t h e present experim e n t s , different m e t h o d s were used for rearing and infecting t h e birds. Based on t h e parameters studied in t h e u n m e d i c a t e d pens of Experiment 1, t h e floor-seeder and wire-seeder t r e a t m e n t s p r o d u c e d a severe coccidiosis while t h e floor-litter m e t h o d p r o d u c e d a milder infection. Similar results occurred in u n m e d i c a t e d pens in E x p e r i m e n t 2 with directly-seeding ( m o d e r a t e coccidiosis) and indirectly-seeding (mild coccidiosis). T h e indirect-seeding m e t h o d is p r o b a b l y closest t o t h e m e t h o d of occyst exposure f o u n d in t h e field. However, t h e o t h e r exposure m e t h o d s provide an indication of t h e performance of an anticoccidial u n d e r conditions of different disease severity and an indication of field performance. T h e 6 0 t h r o u g h 1 0 0 p . p . m . medication levels of salinomycin used in these trials s h o w e d effective anticoccidial activity with b o t h m o d erate and severe coccidiosis e x p o s u r e w h e n
examined with t h e parameters of m o r t a l i t y , average live bird weight, feed conversion, and lesion scores. Analysis of t h e lesion scores showed t h a t salinomycin was q u i t e effective against species of Eimeria infecting t h e u p p e r area of the intestine. Except for a greater weight gain with salinomycin at 4 and 8 weeks in one g r o u p in E x p e r i m e n t 1, n o significant differences were n o t e d b e t w e e n this c o m p o u n d and monensin. T h e d a t a o b t a i n e d from experim e n t s indicated t h a t salinomycin should exhibit good field performance in broiler rearing u n d e r commercial conditions. ACKNOWLEDGMENTS T h e assistance of t h e following individuals is gratefully a c k n o w l e d g e d : Wayne A n d e r s o n , Mrs. Priscilla Carter, Dennis Dykstra, Thorsteinn Karlsson, Russell Major, R o b e r t Smith, and Dale R. Witlock. Coccivac D was generously supplied b y Sterwin Laboratories, Opelika, Alabama. REFERENCES Brewer, R. N., and L. M. Kowalski, 1970. Coccidiosis: Evaluation of anticoccidial drugs in floor-pen trials. Exp. Parasitol. 2 8 : 6 4 - 7 1 . Danforth, H. D., M. D. Ruff, W. M. Reid and R. L. Miller, 1977. Antiococcidal activity of salinomycin in battery raised broiler chickens. Poultry Sci. 56: 926-932. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11:1—42. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: Lesion scoring technique in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Reid, W. M., 1971. Anticoccidials-methods of testing
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Unmedicated Unmedicated 60 p.p.m. salinomycin 60 p.p.m. salinomycin 80 p.p.m. salinomycin 80 p.p.m. salinomycin 100 p.p.m. salinomycin 100 p.p.m. salinomycin 100 p.p.m. monensin 100 p.p.m. monensin
2
938
DANFORTH, RUFF, REID AND JOHNSON
and evaluation. XIX World Veterinary Congress, August 1971, Mexico City, 2:478-480, 3:1186. Reid, W. M., R. N. Brewer, J. Johnson, E. M. Taylor, K. S. Hegde and L. M. Kowalski, 1969. Evaluation of techniques used in studies on efficacy of anticoccidial drugs in chickens. Am. J. Vet. Res. 30:447-459.
Reid, W. M., J. Johnson and J. Dick, 1975. Anticoccidial activity of lasalocid in control of moderate and severe coccidiosis. Avian Diseases, 19:12—18. Ruff, M. D., W. M. Reid and A. P. Rahn, 1976. The effectiveness of different levels of monensin in the control of coccidiosis in broilers. Am. J. Vet. Res. 37:963-967.
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Poultry Science 56:933-938, 1977 INTRODUCTION The fermentation product salinomycin ( A H R - 3 0 9 6 , A. H. Robins) has been shown in laboratory e x p e r i m e n t s t o be an effective anticoccidial agent against mixed and single species Eimeria infections in chickens (Danforth etal., 1977). However, these experiments give only limited d a t a o n t h e possible efficacy of this c o m p o u n d u n d e r commercial p o u l t r y conditions. Floor-pen e x p e r i m e n t s (Brewer and Kowalski, 1 9 7 0 ; Reid et al, 1969, 1975) provide broiler p r o d u c t i o n conditions similar t o those seen in t h e field, and are recognized as a reliable m e t h o d for predicting field perform a n c e of new anticoccidials. In two separate floor-pen experiments, t h e efficacy of salinomycin was compared with t h e reference anticoccidial monensin and u n m e d i ated infected controls. To test anticoccidial activity various techniques were e m p l o y e d t o insure severe t o mild exposure t o coccidiosis. MATERIALS AND METHODS In t w o e x p e r i m e n t s , 1,800 or 2,000-day broiler-type cockerel chicks (Cobb hybrids) were grown in 36 or 4 0 floor-pens (approximately 4.8 square meters) each containing 50 birds. T h e pen-floors were cleaned before t h e trial and covered with a p p r o x i m a t e l y 9 cm. of new pine shavings of litter. Each pen was subdivided into t w o parts with heavy paper
being laid over t h e back half of t h e pen t o prevent accidental exposure t o oocysts. During t h e starting period (10 days, E x p e r i m e n t 1; 21 days, Experiment 2) personnel were denied access to this p o r t i o n of t h e p e n . T h e principal birds were started here and later transferred t o t h e front half of t h e pen for oocyst e x p o s u r e (10 days, E x p e r i m e n t 1; 21 days, E x p e r i m e n t 2). T h e pen divider and paper covering t h e back part of t h e pen were removed o n e day after exposure. A basal diet of open formula broiler starter ration (Ruff et al., 1 9 7 6 ) was fed t h e first four weeks of t h e trial and a finisher formula was used during t h e last four weeks of t h e trial. Modified commercial broiler m a n a g e m e n t was followed in all pens for b o t h e x p e r i m e n t s . To provide exposure t o coccidiosis in different degrees of severity, different c o m b i n a tions of seeding t h e litter and starting t h e principal birds were used as follows: Experiment 1: Method 1. T h e principal birds w e r e started o n t h e floor in t h e back p o r t i o n of t h e pen. For oocysts exposure White Leghorn males were infected at t w o w e e k s of age and placed 5 days after infection (one day before principal birds arrived) in suspended cages on u n m e d i c a t e d feed where droppings could fall on t h e litter in t h e front p o r t i o n of t h e floor-pen. F o r each pen three seeder birds were inoculated with 10 X Coccivac D (containing eight species of Eimeria, E. acervulina, E.
933
Downloaded from http://ps.oxfordjournals.org/ at University of Arizona on December 18, 2014
ABSTRACT The anticoccidial agent salinomycin (AHR-3096) was compared at various treatment levels (60 to 100 p.p.m.) in two experiments against unmedicated and either 100 or 121 p.p.m. monensin-medicated groups to evaluate its performance under floor-pen conditions. Various methods for the initial rearing of birds and coccidial exposure were employed to test the efficacy of salinomycin against severe, moderate, and mild coccidiosis. Salinomycin at all treatment levels showed definite anticoccidial activity resulting in improved weights, feed conversion ratios, lesion scores, and mortality compared with unmedicated controls. In pens with severe coccidiosis, this compound demonstrated a significant improvement in all parameters when compared with the corresponding unmedicated controls. Salinomycin-treated pens exposed to light coccidiosis usually had a numerical increase in the parameters over the unmedicated control groups. Statistical analysis of overall main effects on mortality, weight gain, and feed conversion ratio showed no significant differences between the activity of any level of salinomycin and monensin.
934
DANFORTH, RUFF, REID AND JOHNSON
Method 3. As a further precaution to prevent artificial exposure, the principal birds were maintained for ten days in wire-floored battery brooders located in the pens. These birds were then transferred to the litter contaminated from seeder-birds managed in the same manner as in Method 1. Method 3 has been designated "wire-seeders". Each of these three seeding methods was included to provide production data on three different medication regimens: 100 p.p.m. salinomycin, 121 p.p.m. monensin and unmedicated controls. A total of 36 pens were used with 4 pen replications for each of the 9 treatments. Experiment 2. All principal birds were raised for 21 days in the back portion of the divided floor-pen as in Method 1 above. Two methods of exposure were employed to test the protection of anticoccidials against different degrees of coccidiosis. Severe exposure ("direct seeding") was provided by using seeder birds as described above in Method 1. The seeder birds were inoculated on day 3 with either 10 X Coccivac D or two different field strain isolates containing E. tenella, E. acervulina, E. brunetti and E. maxima. Mild exposure ("indirect seeding") came from oocysts brought in accidentally by shoes, equipment, and dirt. Five pens randomly selected both from direct and indirect seeding groups were each placed on one of the following anticoccidial regimes: 60 p.p.m. salinomycin, 80 p.p.m.
salinomycin, 100 p.p.m. salinomycin, 100 p.p.m. monensin or unmedicated controls. Parameters used in both experiments to evaluate anticoccidial activity were: 1) coccidiosis mortality, 2) total mortality, 3) average weight of live birds at four and eight weeks, 4) feed conversion at four and eight weeks, and 5) average lesion scores. Four birds per pen per time were lesion scored (Johnson and Reid, 1970) at 18 and 28 days in Experiment 1, and 28 and 38 days in Experiment 2. These times corresponded to 9 and 19 days after exposure to oocysts (Experiment 1), and 7 and 17 days after exposure (Experiment 2). All data were submitted to an analysis of variance and Duncan's multiple range test (Duncan, 1955). Differences were recorded as significant whenever probability (P) was less than 0.05.
RESULTS Mortality and Severity of Coccidial Infection. Mortality from coccidiosis in the unmedicated pens was used as the primary criterion for judging severity of the coccidial exposure and subsequent infection. Based on this parameter, the floor-seeders and wire-seeders groups, Experiment 1, produced severe coccidiosis (17% and 24% mortality, respectively, Table 1). Moderate coccidiosis was found in the floorfecal seeding group, Experiment 1, and the direct seeding group, Experiment 2 (3% and 2% mortality, respectively, Tables 1 and 2). Mild coccidiosis (no mortality) occurred with indirect seeding, Experiment 2. All treatment levels of salinomycin and monensin medication either prevented or decreased coccidiosis-induced mortality when compared with the unmedicated controls (Experiments 1 and 2, Tables 1 and 2). No significant difference in mortality was seen between salinomycin and monensin. Weights. Salinomycin-medicated groups showed a significant increase in the average weight of live birds in all seeded pens when compared with the weight of unmedicated controls in both experiments (Tables 1 and 2). A numerical but not statistical increase in weight gain was seen with the 80 and 100 p.p.m. salinomycin in non-seeded pens (Experiment 2, Table 2). In Experiment 1, 100 p.p.m. salinoymcin produced a significantly higher average weight of live birds in the floor-seeder treatment at both four and eight weeks than did 121 p.p.m. monensin (Table 1). In all other
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brunetti, E. maxima, E. mitis, E. mivati, E. necatrix, E. praecox, and E. tenella). Three other birds were inoculated with a mixture of recent field isolates containing six species of Eimeria oocysts (E. acervulina, E. mivati, E. maxima, E. necatrix, E. brunetti, and E. tenella). Seeder birds were removed after 10 days. Moisture levels were increased under these seeder-bird cages to at least 30 percent. This method is hereafter identified as "floor-seeders". Method 2. Principal birds were raised on the floor as in Method 1. Litter in the front half of the pen was contaminated by spreading feces containing oocysts (approximately 50% sporulated). This fecal material had been collected between 6 to 10 days post-inoculation from 10 birds reared in batteries. Half of these birds were inoculated with 10 X Coccivac D and the remaining five were inoculated with the same field isolates used in Method 1. This method of exposure is designated as "floor-fecal seeding".
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treatments there were no statistical differences in weight gain between the salinomycin and monensin medicated pens. An analysis of main effects of salinomycin and monensin on weight gain showed no overall significant differences between the two medications. Feed Conversions. Feed conversions at eight weeks in Experiment 1 are expressed in two different columns because of the death of a number of birds from laryngotraceitis two days before termination of this trial (Table 1). The adjusted feed conversion column includes the weight of the birds which died from that disease. Birds medicated with either 100 p.p.m. salinomycin or monensin in this experiment had significantly lower feed conversion ratios than did the unmedicated control groups. The feed conversion at four and eight weeks in the 60 to 100 p.p.m. salinomycin-medicated seeded pens in Experiment 2 were significantly better than in the unmedicated seeded pens (Table 2). No significant difference in fourweek feed conversions was seen between nonseeded pens, either medicated or unmedicated. However, at eight weeks the medicated nonseeded pens did show a significantly lower feed conversion. At four weeks, feed conversion in the monensin-medicated, seeded pens was significantly better than in the 80 p.p.m. salinomycin-medicated pens. However, main effect analysis showed no overall significant differences in the effect of salinomycin and monensin on feed conversion ratios. Lesion Scores. Salinomycin-medicated birds in Experiments 1 and 2 had reduced lesions in the three areas of the intestine and the ceca when compared with unmedicated birds in the seeded pens (Figs. 1 and 2). There was no significant difference seen between the total lesion scores for either monensin or the three levels of salinomycin (60—100 p.p.m. In Experiment 1, the lesion score in the middle and lower intestinal areas was significantly lowered by salinomycin in the floorseeder and wire-seeder treatments. By 19 days after bird exposure, the lesion scores in the various areas had decreased to a level in the unmedicated controls where the effects of medication were not apparent in any one particular intestinal area. However, the total lesion score showed a significant reduction in the salinomycin and monensin groups when compared with the unmedicated controls (Fig. 1). In Experiment 2, a numerical decrease in
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935
DANFORTH, RUFF, REID AND JOHNSON
936
9 Days Post
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FIG. 1. Effect of medication on intestinal lesion scores in broilers, Experiment 1. Total lesion scores within a time period not having a common letter are significantly different (P<0.05). 0 = unmedicated; S = 100 p.p.m. salinomycin; M = 121 p.p.m. monensin.
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FIG. 2. Effect of medication on intestinal lesion scores in broilers, Experiment 2. Total lesion scores within a time period not having a common letter are significantly different (P<0.05). + = direct seeding (seeder birds); — = indirect seeding (no seeder birds).
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MEDICATION
ANTICOCCIDIAL ACTIVITY OF SALINOMYCIN
937
TABLE 2. — Anticoccidial activity of salinomycin in floor pens (Experiment 2)1
Oocysts seeding
Treatment
Coccidiosisassociated mortality 4/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200 0/200
Average feed conversion
Average wt. gain in kg. 4 weeks
8 weeks
4 weeks
8 weeks
0.65lt> 0.716 a 0.714^ 0.711* 0.713* 0.699 a 0.717* 0.707a 0.717a 0.720a
1.836 c 1.950bc 2.094ab 2.102a 2.062ab 2.069 a b 2.055 a b 2.023 a b 2.086ab 2.118a
1.715a 1.632bc 1.66lbc 1.650bc 1.669 b 1.672b 1.634bc 1.654bc 1.624 c 1.67lb
2.227a 2.125b 2.049 c 2.056 c 2.033 c 2.025 c 2.044 c 2.025C 2.03 7C 2.044C
1
Means within a parameter not followed by a common superscript letter are significantly different (P<0.05).
2
+ = direct seeding (seeder birds); — = indirect seeding (no seeder birds).
lesions was seen in t h e seeded pens as t h e level of salinomycin medication increased. All nonseeded medicated pens showed significantly lower scores at seven days after oocysts e x p o sure when c o m p a r e d with t h e u n m e d i c a t e d non-seeded pens. Only t h e pens fed 8 0 p . p . m . salinomycin showed significantly lower total lesion scores t h a n t h e u n m e d i c a t e d pens at 17 days post-exposure. DISCUSSION Floor-pen e x p e r i m e n t s are recognized as a reliable testing t e c h n i q u e for predicting t h e field performance of new anticoccidial comp o u n d s (Reid, 1 9 7 1 ) . In t h e present experim e n t s , different m e t h o d s were used for rearing and infecting t h e birds. Based on t h e parameters studied in t h e u n m e d i c a t e d pens of Experiment 1, t h e floor-seeder and wire-seeder t r e a t m e n t s p r o d u c e d a severe coccidiosis while t h e floor-litter m e t h o d p r o d u c e d a milder infection. Similar results occurred in u n m e d i c a t e d pens in E x p e r i m e n t 2 with directly-seeding ( m o d e r a t e coccidiosis) and indirectly-seeding (mild coccidiosis). T h e indirect-seeding m e t h o d is p r o b a b l y closest t o t h e m e t h o d of occyst exposure f o u n d in t h e field. However, t h e o t h e r exposure m e t h o d s provide an indication of t h e performance of an anticoccidial u n d e r conditions of different disease severity and an indication of field performance. T h e 6 0 t h r o u g h 1 0 0 p . p . m . medication levels of salinomycin used in these trials s h o w e d effective anticoccidial activity with b o t h m o d erate and severe coccidiosis e x p o s u r e w h e n
examined with t h e parameters of m o r t a l i t y , average live bird weight, feed conversion, and lesion scores. Analysis of t h e lesion scores showed t h a t salinomycin was q u i t e effective against species of Eimeria infecting t h e u p p e r area of the intestine. Except for a greater weight gain with salinomycin at 4 and 8 weeks in one g r o u p in E x p e r i m e n t 1, n o significant differences were n o t e d b e t w e e n this c o m p o u n d and monensin. T h e d a t a o b t a i n e d from experim e n t s indicated t h a t salinomycin should exhibit good field performance in broiler rearing u n d e r commercial conditions. ACKNOWLEDGMENTS T h e assistance of t h e following individuals is gratefully a c k n o w l e d g e d : Wayne A n d e r s o n , Mrs. Priscilla Carter, Dennis Dykstra, Thorsteinn Karlsson, Russell Major, R o b e r t Smith, and Dale R. Witlock. Coccivac D was generously supplied b y Sterwin Laboratories, Opelika, Alabama. REFERENCES Brewer, R. N., and L. M. Kowalski, 1970. Coccidiosis: Evaluation of anticoccidial drugs in floor-pen trials. Exp. Parasitol. 2 8 : 6 4 - 7 1 . Danforth, H. D., M. D. Ruff, W. M. Reid and R. L. Miller, 1977. Antiococcidal activity of salinomycin in battery raised broiler chickens. Poultry Sci. 56: 926-932. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11:1—42. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: Lesion scoring technique in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Reid, W. M., 1971. Anticoccidials-methods of testing
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Unmedicated Unmedicated 60 p.p.m. salinomycin 60 p.p.m. salinomycin 80 p.p.m. salinomycin 80 p.p.m. salinomycin 100 p.p.m. salinomycin 100 p.p.m. salinomycin 100 p.p.m. monensin 100 p.p.m. monensin
2
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DANFORTH, RUFF, REID AND JOHNSON
and evaluation. XIX World Veterinary Congress, August 1971, Mexico City, 2:478-480, 3:1186. Reid, W. M., R. N. Brewer, J. Johnson, E. M. Taylor, K. S. Hegde and L. M. Kowalski, 1969. Evaluation of techniques used in studies on efficacy of anticoccidial drugs in chickens. Am. J. Vet. Res. 30:447-459.
Reid, W. M., J. Johnson and J. Dick, 1975. Anticoccidial activity of lasalocid in control of moderate and severe coccidiosis. Avian Diseases, 19:12—18. Ruff, M. D., W. M. Reid and A. P. Rahn, 1976. The effectiveness of different levels of monensin in the control of coccidiosis in broilers. Am. J. Vet. Res. 37:963-967.
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