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Anticoccidial Activity of Narasin in Broiler Chickens Reared in Floor Pens
Anticoccidial Activity of Narasin in Broiler Chickens Reared in Floor Pens M. D. RUFF, 1 W. M. REID, and A. P. RAHN 2 Department of Poultry Science, University of Georgia, Athens, Georgia 30602 L. R. McDOUGALD3 Eli Lilly and Company, Greenfield, Indiana 46140 (Received for publication December 10, 1979)
1980 Poultry Science 59:2008-2013 INTRODUCTION
Narasin is a polyether antibiotic (ionophore) efficacious against coccidiosis under controlled laboratory conditions (Weppelman etal., 1977; Ruff et al., 1979), but performance data obtained in the laboratory are not always indicative of drug efficacy in floor-reared birds. A prime example is monensin, which fails to control lesions of some Eimeria species in the laboratory but which is highly successful in actual usage under field conditions (Ryley and Wilson, 1975). Floor pen trials are important in the evaluation of anticoccidial compounds and can help bridge the gap between laboratory trials and expensive, large scale field trials (James, 1978). The present study measured 1) the anticoccidial efficacy of narasin in floor-
1
Present address: US Department of Agriculture, Animal Parasitology Institute, Beltsville Agricultural Research Center, Beltsville, MD 20705. 2 Present address: Department of Poultry Science, Michigan State University, East Lansing, MI 48824. 3 Present address: Department of Poultry Science, University of Georgia, Athens, GA 30602.
reared broilers and 2) subsequent development of host immunity to reinfection with coccidia. MATERIALS AND METHODS Experimental Design. Three trials were conducted to measure drug efficacy. Cobb male broilers were used in all trials. Each treatment group was composed of five pens of 50 birds each. Each pen was divided in half by a wire divider for the start of the trials. The principal birds were restricted to the back half of the pen from day 0 until day 7 (Trial 1) or day 10 (Trials 2 and 3). Personnel were not allowed to enter the back half of the pen once the litter was installed. These procedures prevented exposure of the principal birds to coccidia until the desired time. Coccidial Exposure. Exposure of the principal birds to coccidia was accomplished by contaminating the pens with the seeder bird technique. The moisture in the litter was brought up to 30% ± 5% before the introduction of the seeder birds and maintained at that level throughout the trial. In Trial 1, seeder birds (White Leghorn cockerels) were inoculated 15 days prior to the arrival of the principal birds
2008
Downloaded from http://ps.oxfordjournals.org/ at Serials Section, Dixson Library on June 12, 2015
ABSTRACT The anticoccidial activity of the ionophore narasin was tested in 3 floor-pen experiments. Narasin was tested at levels of 40, 60, 80, 100, or 120 ppm and compared against feeding ration containing 80, 100, or 121 ppm monensin or no medication. Feeding at all levels of narasin significantly prevented coccidiosis-induced mortality and improved weight gains and feed conversion ratios compared with the same parameters in groups given unmedicated feed. Protection with narasin was equal to or slightly greater than the protection obtained with monensin. The reduction in intestinal lesion scores was greater with narasin medication than with monensin. Analysis of pooled data from these trials indicated that a level between 48 and 96 ppm narasin would provide the optimum, depending on whether maximum weight gain or optimum feed conversion ratio was desired. Testing for coccidial immunity using the immunity challenge technique indicated that, based on the parameters of weight gain and lesion scores, even levels as low as 40 ppm narasin had enough efficacy to significantly reduce the amount of immunity which developed in medicated birds compared with the level of immunity developed in birds receiving unmedicated feed. (Key words: coccidia, chicken, anticoccidial, narasin)
NARASIN AND COCCIDIOSIS
After 1 week, the birds were weighed and 10 birds from each treatment were challenged with an inoculum containing 1,000,000 E. acervulina; 200,000 E. brunetti; 200,000 E. maxima; 1,000,000 E. mivati; 100,000 E. necatrix; and 100,000 E. tenella sporulated oocysts/bird. The remaining 5 birds/treatment were kept uninoculated. Fifteen additional birds of the same age as the floor-pen birds raised free of coccidiosis in wire-floored cages were used as susceptible controls. Ten of these birds were inoculated and 5 uninoculated. Seven days after inoculation, the birds were weighed and lesions were scored. RESULTS Mortality and Weight Gain. In Trial 1 the severity of coccidial exposure was insufficient to produce mortality in the unmedicated birds (Table 1). In Trials 2 and 3 a 4.4% to 5.6% mortality was found (Tables 2 and 3). Medication significantly reduced coccidiosis induced mortality, although in Trial 2 40 ppm narasin and 100 ppm monensin were not as effective as higher levels of narasin. The average live weight of birds at 4 and 8 weeks was significantly greater in medicated groups than in birds receiving no medication (Tables 1, 2, and 3). Feed Conversion Ratios. At 4 weeks the feed conversion ratio of birds receiving unmedicated feed in all three trials was numerically greater than the feed conversion ratios from birds receiving medicated feed. In Trials 2 and 3, which involved heavy coccidiosis, these differences were statistically significant. Likewise, at 8 weeks of age, birds receiving unmedicated feed had numerically higher feed conversion ratios, although these differences were not always significant. Lesion Scores. Analysis of regional and total lesion scores in Trials 2 and 3 indicated no significant differences between trials. Therefore, data from these two experiments were pooled (Fig. 1). At 7 days postexposure, regional and total lesion scores were significantly lowered as the level of narasin increased. Lesion scores at 100 and 120 ppm narasin were significantly lower than those seen in birds fed a ration containing 100 ppm monensin. At 17 days postexposure, medicated birds still had significantly less lesions than birds receiving unmedicated feed although differences related to medication level were not as pronounced. Immunity Challenge. Susceptible control birds, raised in cages for their entire life cycle,
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and placed on litter in the back half of each floor pen. Seeders were removed 3 days before the principal birds arrived and Kraft paper placed over the contaminated litter. In Trials 2 and 3, the seeder birds were inoculated with coccidia 4 days prior to the arrival of the principal birds, placed in suspended cages in the front half of each floor pen on the day the principal birds arrived, and removed 6 days later. Principal birds were exposed to oocysts by removing the divider or Kraft paper on day 7 (Trial 1) or day 10 (Trials 2 and 3). Ten seeders were used in each pen. Five of these seeders had been inoculated with 15x Coccivac D which contained eight species of Eimeria: E. acervulina, E. brunetti, E. maxima, E. mitis, E. mivati, E. pracox, and E. tenella. The remaining 5 seeders had been inoculated with a mixture of six Eimeria species which had been recently obtained from the field — E. acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix, and E. tenella. Seeders were fed only unmedicated feed and additional inoculated seeders were held in batteries to replace those that died. Medication. A basal diet of open formula broiler starter ration (Ruff et al., 1976) was fed the first 4 weeks of each trial and a finisher ration during the last 4 weeks. The ration was medicated as follows: Trial 1 — 40, 60, 80, or 100 ppm narasin or 80, 100, or 121 ppm monensin; Trials 2 and 3 - 40, 60, 80, 100, or 120 ppm narasin or 100 or 121 ppm (Trial 3 only) monensin. A control group (5 pens) was fed unmedicated feed in each trial. Parameters. Parameters used to measure drug efficacy were: 1) coccidiosis induced mortality, 2) total mortality, 3) average live weight at 4 and 8 weeks, 4) feed conversion ratio at 4 and 8 weeks, and 5) average intestinal lesion score. Lesions were scored (Johnson and Reid, 1970) on 4 birds/pen on days 15 and 25 (Trial 1) or days 17 and 28 (Trials 2 and 3) by gross examination of the upper, middle, and lower small intestine and ceca. These times corresponded to 7 and 17 days (Trial 1) or 7 and 18 days (Trials 2 and 3) after the principal birds were exposed to coccidia. Presence of coccidial lesions was confirmed by microscopic examination. Immunity Challenge. At the termination of Trial 2, when birds were 8 weeks of age, 3 birds were removed from each pen (15 birds/treatment). These birds were transferred to colony type cages with wire floors and fed unmedicated feed to allow any existent infections to subside.
2009
2010
RUFF ET AL. TABLE 1. Anticoccidial activity of narasin, Trial 1 4 Weeks
Treatm ent Drug
Mortality1
(ppm)
—<%)
0 40 60 80 100 80 100 121
0a a .4a 0a 0a 0a 0a 0a
Mortality'
1.71 a 1.53 c 1.56 bc 1.53 c 1.54c 1.61 b c 1.64 ab 1.63 a b
0a 0a .4a 0a .4a .4a .8a 0a
(%)
(kg) .54 b .64 a .64 a .64 a .64 a .60 a .62 a .64 a
o
8 Weeks Feed2 conversion
Average live weight
Feed 2 conversion
(kg) 1.88 b 2.02 a 2.03 a 1.99 a 2.00 a 1.95 a b 1.96 ab 1.99a
2.05 a 2.00 b c 1.97c 1.98 b c 2.01abc 2.03ab 2.02 a b 2.02 a b
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
lost weight when challenged with coccidia (Table 4). Conversely, the weight gain of birds which had been fed unmedicated feed while on the floor was not depressed from that in nonchallenged susceptible controls. With an initial level of 40 or 60 ppm narasin or 100 ppm monensin, weight gain was significantly less after challenge than that in the respective nonchallenged controls. Weight gain after challenge was further depressed in those birds which had previously received 80, 100, or 120 ppm narasin. The effect of previous medication on lesion scores following the challenge infection was similar to the pattern seen with
weight gain. Lesions were fewest in those birds which had previously been given only unmedicated feed and progressively increased as the level of narasin medication increased. The high regional and total lesion score in the challenged control birds indicated that the challenge infection was extremely severe. DISCUSSION Narasin proved to be an effective prophylactic medication for the control of coccidiosis on floor raised birds under conditions of mild (Trial 1) and severe (Trials 2 and 3) coccidial exposure. These conclusions were
TABLE 2. Anticoccidial activity of narasin, Trial 2 8 Weeks
4 Weeks Treatm ent Drug
Level
Mortality1
(ppm) None Narasin Narasin Narasin Narasin Narasin Monensin
0 40 60 80 100 120 100
(%) 4.4 a 2.0 b 0C
Ac 0C .8C
2.0 b
Average live weight
Feed 2 conversion
Mortality 1
<%)
(kg) .61b .72 a .71a .72 a .73 a .72 a .71a
1.69a 1.57 b 1.56 b 1.55 b 1.55 b 1.57 b 1.59 b
4.4 a 2.0 b OC
.4 C 0C .8C
2.0 b
Average live weight (kg) — 1.88 c 2.04 a 2.05 a 2.01ab 2.02 a 1.95 b 2.02 a
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
Feed2 conversion
2.02 a 1.97 ab 1.93 b 1.94 b 1.96 ab 1.98 ab 1.96 ab
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None Narasin Narasin Narasin Narasin Monensin Monensin Monensin
Level
Average live weight
NARASIN AND COCCIDIOSIS
2011
TABLE 3. Anticoccidial activity of narasin, Trial 3 4 Weeks Treatme nt Drug
Mortality1
(ppm)
— (%)
0 40 60 80 100 120 100 121
4.8
a
.4b .4b 0b 0b 0b .4b 0b
Average ive weight
Feed conversion
Mortality1
(kg) b
58 70a 70a 73a 73a 71a 71a 69a
a
1.85 1.65 b 1.69 b 1.65 b 1.65 b 1.62 b 1.64 b 1.67 b
5.6
Average live weight
(%)
^ k g ^
a
1.88 b 2.01 a 1.98a 2.01 a 2.04 a 2.00 a 2.00 a 2.00 a
,4b .4b 0b 0b Ob .4b Ob
conversion
2.00 a 1.99 ab 1.96 a b c 1.94bc 1.96 ab c 1.90 c 1.92 c 1.93bc
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
based on the parameters of mortality, average weight of live birds at 4 and 8 weeks, feed conversion ratios at 4 and 8 weeks, and intestinal lesion scores. These results are in keeping with reports on the efficacy of narasin against individual and mixed species of Eimeria in battery raised broilers (Weppelman et al., 1977; Ruff et al., 1979). Average live weight and feed conversion ratio in birds receiving 80 or 100 ppm narasin were generally comparable or slightly superior to birds receiving 100 or 121 ppm monensin, although differences were not significant. Ruff et al. (1976) utilized regression procedures to analyze and evaluate possible economic tradeoffs of monensin medication in floor-reared broilers. A similar type analysis which involved severe coccidiosis was made on data from Trials 2 and 3 in the present study. An equation specification of a plausible functional form was selected as giving the best fit if it had the lowest mean square error, conditional upon the rejection of the null-hypothesis that the unknown parameters were equal to zero. The parameter estimates from these equations were in turn used to calculate the implied level of maximum medication effectiveness. No differences in the slopes of the estimated 'relations were found between Trials 2 and 3 for the 8 week body weight and lesion score regression variables. The relationship of 8 week body weight to narasin medication level was implied to be a quadratic function and the maximum weight gain was predicted to occur at
48 ppm narasin. The relationship of total lesion score to level of narasin was implied to be a linear equation at both 7 and 18 days postexposure. The regression coefficients indicated that the total lesion score declined 1.36% or .69% for every additional ppm of narasin at the 7 and 18 days postexposure, respectively. A difference between Trials 2 and 3 in both slope and intercept of a quadratic equation was identified for the 8 week feed conversion relationship. The levels of narasin giving the lowest feed conversion ratio estimate were 80 ppm and 110 ppm in Trials 2 and 3, respectively. These results suggest optimum narasin levels from an economic perspective (Rahn, 1978) would be greater than 48 ppm (predicted
7 DAYS POST EXPOSURE
•
•
17 DAYS POST EXPOSURE
Upper
Mid Lower Ceca
PPM
0 I-
40
60
0
80 100 120 100
NARASIN
-|
tl
I-
40
60
SO 100 120 100
NARASIN
-I
I I
FIG. 1. Pooled lesion scores for 4 regions of the intestine, Trials 2 and 3.
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None Narasin Narasin Narasin Narasin Narasin Monensin Monensin
Level
8 Weeks 2
2012
RUFF ETAL. TABLE 4. Immunity challenge of broilers raised in floor pens, Trial 2* Lesion score 3
Original t r e a t m e n t Drug
Level —(ppm y(caged raised) 0 40 60 80 100 120 100
U
M
L
c
T
3.5a .6 C 1.7 b 2.5b 3.2a 3.6a 3.2a 2.4b
3.6a .yd 1.8 C 2.6b 3.1ab 3.3a 3.1ab 2.9ab
3.1a 3f 6* 8def 1 3de 2 2bc 2 3b 1 5cd
3.1a .4«1 .5" .6cd 1.0cd 1.9 b 1.2bcd 1.4bc
13.3a 2.0e 4.6d 6.5d 8.6 C 11.0b 9.8be 8.2 C
(%) -3.ld 95a 62b 60b 22c icd 12cd 52.5b
n h c (i c f ' ' ' ' ' Values within a column not followed by a common letter are significantly different (P<.05). 1 Control birds were cage raised and never exposed to coccidiosis before challenge. Other birds raised on floor for 8 weeks with medication as indicated. These birds were held in cages for one week prior to challenge and given unmedicated feed. Challenge dose for each species (sporulated oocysts/bird): 1,000,000 E. tenella and E. necatrix-, 200,000 /:'. maxima and E. brunetti, 1,000,000 E. acervulina and E. mivati. 2
Compared with the weight gain of five unchallenged birds of the same original treatment.
3
Severity of coccidiol lesions at 7 days postchallenge; 0 = no lesions, 4 = most severe. Scores shown are those in the upper (U), middle (M), lower (L), or cecal (C) regions and the total lesion score (T).
level of m a x i m u m weight) and less than 95 p p m (the average of the m i n i m u m predicted feed conversion ratios). The results of the i m m u n i t y challenge e x p e r i m e n t indicate that the control of the coccidial infection by all levels of narasin tested was sufficient to prevent maximal development of i m m u n i t y . As indicated by weight gain and lesion score, even levels of 120 p p m narasin allowed s o m e i m m u n i t y to develop based on comparisons of challenge infections in previously u n e x p o s e d cage reared birds. Conversely, even levels as low as 4 0 p p m p r o t e c t e d against the initial immunizing infection to a sufficient degree so that the challenge infection was more severe than that seen in floor birds previously receiving only u n m e d i c a t e d feed. Karlsson and Reid ( 1 9 7 8 ) have previously reported that battery reared broilers i m m u n i z e d with E. tenella were less i m m u n e to challenge infection when the ration contained 80 p p m narasin during the immunizing infection than w h e n the ration was u n m e d i c a t e d . These studies show that the anticoccidial efficacy of narasin previously reported for battery raised birds is also evident in birds reared u n d e r floor pen t y p e conditions. Results also indicate t h a t narasin should prove an effective anticoccidial in field use with activity comparable to t h a t of m o n e n s i n .
ACKNOWLEDGMENTS We t h a n k t h e following people for their assistance during the course of these trials: W. Anderson, H. Danforth, D. Dykstra, J. J o h n s o n , T. Karlsson, R. Major, J. Rasher, P. Smith, and D. Witlock.
REFERENCES James, S., 1978. Coccidial infection in floor pens as a method for the evaluation of anticoccidial drugs. Pages 375—368 in Avian coccidiosis Proc. 13th Poultry Sci. Symp. Brit. Poultry Sci., Ltd., Great Britain. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: lesion scoring techniques in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Karlsson, T„ and W. M. Reid, 1978. Development of immunity to coccidiosis in chickens administered anticoccidials in feed. Avian Dis. 22:487-495. Rahn, A. P., 1978. Economic evaluation of optimum inclusion rate of monensin in broiler diets. Pages 423—434 in Avian coccidiosis Proc. 13th Poultry Sci. Symp. Brit. Poultry Sci., Ltd., Great Britain. Ruff, M. D., W. M. Reid, J. K. Johnson, and W. K. Anderson, 1979. Anticoccicial activity of narasin in battery raised broiler chickens. Poultry Sci. 58:298-303. Ruff, M. D., W. M. Reid, and A. P. Rahn, 1976.
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Control None Narasin Narasin Narasin Narasin Narasin Monensin
Weight gain
2
NARASIN AND COCCIDIOSIS Efficacy of different feeding levels of monensin in the control of coccidiosis in broilers. Amer. J. Vet. Res. 37:963-967. Ryley, J. F., and R. G. Wilson, 1975. Laboratory studies with some recent anticoccidials. Parasitology 70:203-222.
2013
Weppelman, R. M., G. Olson, D. A. Smith, T. Tamas, and A. van Iderstine, 1977. Comparison of anticoccidial efficacy, resistance and tolerance of narasin, monensin and lasalocid in chicken battery trials. Poultry Sci. 56:1550-1559.
Downloaded from http://ps.oxfordjournals.org/ at Serials Section, Dixson Library on June 12, 2015
1980 Poultry Science 59:2008-2013 INTRODUCTION
Narasin is a polyether antibiotic (ionophore) efficacious against coccidiosis under controlled laboratory conditions (Weppelman etal., 1977; Ruff et al., 1979), but performance data obtained in the laboratory are not always indicative of drug efficacy in floor-reared birds. A prime example is monensin, which fails to control lesions of some Eimeria species in the laboratory but which is highly successful in actual usage under field conditions (Ryley and Wilson, 1975). Floor pen trials are important in the evaluation of anticoccidial compounds and can help bridge the gap between laboratory trials and expensive, large scale field trials (James, 1978). The present study measured 1) the anticoccidial efficacy of narasin in floor-
1
Present address: US Department of Agriculture, Animal Parasitology Institute, Beltsville Agricultural Research Center, Beltsville, MD 20705. 2 Present address: Department of Poultry Science, Michigan State University, East Lansing, MI 48824. 3 Present address: Department of Poultry Science, University of Georgia, Athens, GA 30602.
reared broilers and 2) subsequent development of host immunity to reinfection with coccidia. MATERIALS AND METHODS Experimental Design. Three trials were conducted to measure drug efficacy. Cobb male broilers were used in all trials. Each treatment group was composed of five pens of 50 birds each. Each pen was divided in half by a wire divider for the start of the trials. The principal birds were restricted to the back half of the pen from day 0 until day 7 (Trial 1) or day 10 (Trials 2 and 3). Personnel were not allowed to enter the back half of the pen once the litter was installed. These procedures prevented exposure of the principal birds to coccidia until the desired time. Coccidial Exposure. Exposure of the principal birds to coccidia was accomplished by contaminating the pens with the seeder bird technique. The moisture in the litter was brought up to 30% ± 5% before the introduction of the seeder birds and maintained at that level throughout the trial. In Trial 1, seeder birds (White Leghorn cockerels) were inoculated 15 days prior to the arrival of the principal birds
2008
Downloaded from http://ps.oxfordjournals.org/ at Serials Section, Dixson Library on June 12, 2015
ABSTRACT The anticoccidial activity of the ionophore narasin was tested in 3 floor-pen experiments. Narasin was tested at levels of 40, 60, 80, 100, or 120 ppm and compared against feeding ration containing 80, 100, or 121 ppm monensin or no medication. Feeding at all levels of narasin significantly prevented coccidiosis-induced mortality and improved weight gains and feed conversion ratios compared with the same parameters in groups given unmedicated feed. Protection with narasin was equal to or slightly greater than the protection obtained with monensin. The reduction in intestinal lesion scores was greater with narasin medication than with monensin. Analysis of pooled data from these trials indicated that a level between 48 and 96 ppm narasin would provide the optimum, depending on whether maximum weight gain or optimum feed conversion ratio was desired. Testing for coccidial immunity using the immunity challenge technique indicated that, based on the parameters of weight gain and lesion scores, even levels as low as 40 ppm narasin had enough efficacy to significantly reduce the amount of immunity which developed in medicated birds compared with the level of immunity developed in birds receiving unmedicated feed. (Key words: coccidia, chicken, anticoccidial, narasin)
NARASIN AND COCCIDIOSIS
After 1 week, the birds were weighed and 10 birds from each treatment were challenged with an inoculum containing 1,000,000 E. acervulina; 200,000 E. brunetti; 200,000 E. maxima; 1,000,000 E. mivati; 100,000 E. necatrix; and 100,000 E. tenella sporulated oocysts/bird. The remaining 5 birds/treatment were kept uninoculated. Fifteen additional birds of the same age as the floor-pen birds raised free of coccidiosis in wire-floored cages were used as susceptible controls. Ten of these birds were inoculated and 5 uninoculated. Seven days after inoculation, the birds were weighed and lesions were scored. RESULTS Mortality and Weight Gain. In Trial 1 the severity of coccidial exposure was insufficient to produce mortality in the unmedicated birds (Table 1). In Trials 2 and 3 a 4.4% to 5.6% mortality was found (Tables 2 and 3). Medication significantly reduced coccidiosis induced mortality, although in Trial 2 40 ppm narasin and 100 ppm monensin were not as effective as higher levels of narasin. The average live weight of birds at 4 and 8 weeks was significantly greater in medicated groups than in birds receiving no medication (Tables 1, 2, and 3). Feed Conversion Ratios. At 4 weeks the feed conversion ratio of birds receiving unmedicated feed in all three trials was numerically greater than the feed conversion ratios from birds receiving medicated feed. In Trials 2 and 3, which involved heavy coccidiosis, these differences were statistically significant. Likewise, at 8 weeks of age, birds receiving unmedicated feed had numerically higher feed conversion ratios, although these differences were not always significant. Lesion Scores. Analysis of regional and total lesion scores in Trials 2 and 3 indicated no significant differences between trials. Therefore, data from these two experiments were pooled (Fig. 1). At 7 days postexposure, regional and total lesion scores were significantly lowered as the level of narasin increased. Lesion scores at 100 and 120 ppm narasin were significantly lower than those seen in birds fed a ration containing 100 ppm monensin. At 17 days postexposure, medicated birds still had significantly less lesions than birds receiving unmedicated feed although differences related to medication level were not as pronounced. Immunity Challenge. Susceptible control birds, raised in cages for their entire life cycle,
Downloaded from http://ps.oxfordjournals.org/ at Serials Section, Dixson Library on June 12, 2015
and placed on litter in the back half of each floor pen. Seeders were removed 3 days before the principal birds arrived and Kraft paper placed over the contaminated litter. In Trials 2 and 3, the seeder birds were inoculated with coccidia 4 days prior to the arrival of the principal birds, placed in suspended cages in the front half of each floor pen on the day the principal birds arrived, and removed 6 days later. Principal birds were exposed to oocysts by removing the divider or Kraft paper on day 7 (Trial 1) or day 10 (Trials 2 and 3). Ten seeders were used in each pen. Five of these seeders had been inoculated with 15x Coccivac D which contained eight species of Eimeria: E. acervulina, E. brunetti, E. maxima, E. mitis, E. mivati, E. pracox, and E. tenella. The remaining 5 seeders had been inoculated with a mixture of six Eimeria species which had been recently obtained from the field — E. acervulina, E. brunetti, E. maxima, E. mivati, E. necatrix, and E. tenella. Seeders were fed only unmedicated feed and additional inoculated seeders were held in batteries to replace those that died. Medication. A basal diet of open formula broiler starter ration (Ruff et al., 1976) was fed the first 4 weeks of each trial and a finisher ration during the last 4 weeks. The ration was medicated as follows: Trial 1 — 40, 60, 80, or 100 ppm narasin or 80, 100, or 121 ppm monensin; Trials 2 and 3 - 40, 60, 80, 100, or 120 ppm narasin or 100 or 121 ppm (Trial 3 only) monensin. A control group (5 pens) was fed unmedicated feed in each trial. Parameters. Parameters used to measure drug efficacy were: 1) coccidiosis induced mortality, 2) total mortality, 3) average live weight at 4 and 8 weeks, 4) feed conversion ratio at 4 and 8 weeks, and 5) average intestinal lesion score. Lesions were scored (Johnson and Reid, 1970) on 4 birds/pen on days 15 and 25 (Trial 1) or days 17 and 28 (Trials 2 and 3) by gross examination of the upper, middle, and lower small intestine and ceca. These times corresponded to 7 and 17 days (Trial 1) or 7 and 18 days (Trials 2 and 3) after the principal birds were exposed to coccidia. Presence of coccidial lesions was confirmed by microscopic examination. Immunity Challenge. At the termination of Trial 2, when birds were 8 weeks of age, 3 birds were removed from each pen (15 birds/treatment). These birds were transferred to colony type cages with wire floors and fed unmedicated feed to allow any existent infections to subside.
2009
2010
RUFF ET AL. TABLE 1. Anticoccidial activity of narasin, Trial 1 4 Weeks
Treatm ent Drug
Mortality1
(ppm)
—<%)
0 40 60 80 100 80 100 121
0a a .4a 0a 0a 0a 0a 0a
Mortality'
1.71 a 1.53 c 1.56 bc 1.53 c 1.54c 1.61 b c 1.64 ab 1.63 a b
0a 0a .4a 0a .4a .4a .8a 0a
(%)
(kg) .54 b .64 a .64 a .64 a .64 a .60 a .62 a .64 a
o
8 Weeks Feed2 conversion
Average live weight
Feed 2 conversion
(kg) 1.88 b 2.02 a 2.03 a 1.99 a 2.00 a 1.95 a b 1.96 ab 1.99a
2.05 a 2.00 b c 1.97c 1.98 b c 2.01abc 2.03ab 2.02 a b 2.02 a b
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
lost weight when challenged with coccidia (Table 4). Conversely, the weight gain of birds which had been fed unmedicated feed while on the floor was not depressed from that in nonchallenged susceptible controls. With an initial level of 40 or 60 ppm narasin or 100 ppm monensin, weight gain was significantly less after challenge than that in the respective nonchallenged controls. Weight gain after challenge was further depressed in those birds which had previously received 80, 100, or 120 ppm narasin. The effect of previous medication on lesion scores following the challenge infection was similar to the pattern seen with
weight gain. Lesions were fewest in those birds which had previously been given only unmedicated feed and progressively increased as the level of narasin medication increased. The high regional and total lesion score in the challenged control birds indicated that the challenge infection was extremely severe. DISCUSSION Narasin proved to be an effective prophylactic medication for the control of coccidiosis on floor raised birds under conditions of mild (Trial 1) and severe (Trials 2 and 3) coccidial exposure. These conclusions were
TABLE 2. Anticoccidial activity of narasin, Trial 2 8 Weeks
4 Weeks Treatm ent Drug
Level
Mortality1
(ppm) None Narasin Narasin Narasin Narasin Narasin Monensin
0 40 60 80 100 120 100
(%) 4.4 a 2.0 b 0C
Ac 0C .8C
2.0 b
Average live weight
Feed 2 conversion
Mortality 1
<%)
(kg) .61b .72 a .71a .72 a .73 a .72 a .71a
1.69a 1.57 b 1.56 b 1.55 b 1.55 b 1.57 b 1.59 b
4.4 a 2.0 b OC
.4 C 0C .8C
2.0 b
Average live weight (kg) — 1.88 c 2.04 a 2.05 a 2.01ab 2.02 a 1.95 b 2.02 a
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
Feed2 conversion
2.02 a 1.97 ab 1.93 b 1.94 b 1.96 ab 1.98 ab 1.96 ab
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None Narasin Narasin Narasin Narasin Monensin Monensin Monensin
Level
Average live weight
NARASIN AND COCCIDIOSIS
2011
TABLE 3. Anticoccidial activity of narasin, Trial 3 4 Weeks Treatme nt Drug
Mortality1
(ppm)
— (%)
0 40 60 80 100 120 100 121
4.8
a
.4b .4b 0b 0b 0b .4b 0b
Average ive weight
Feed conversion
Mortality1
(kg) b
58 70a 70a 73a 73a 71a 71a 69a
a
1.85 1.65 b 1.69 b 1.65 b 1.65 b 1.62 b 1.64 b 1.67 b
5.6
Average live weight
(%)
^ k g ^
a
1.88 b 2.01 a 1.98a 2.01 a 2.04 a 2.00 a 2.00 a 2.00 a
,4b .4b 0b 0b Ob .4b Ob
conversion
2.00 a 1.99 ab 1.96 a b c 1.94bc 1.96 ab c 1.90 c 1.92 c 1.93bc
' ' Values within a column not followed by a common letter are significantly different (P<.05). 1
Coccidiosis induced.
2
Ratio of feed/gain.
based on the parameters of mortality, average weight of live birds at 4 and 8 weeks, feed conversion ratios at 4 and 8 weeks, and intestinal lesion scores. These results are in keeping with reports on the efficacy of narasin against individual and mixed species of Eimeria in battery raised broilers (Weppelman et al., 1977; Ruff et al., 1979). Average live weight and feed conversion ratio in birds receiving 80 or 100 ppm narasin were generally comparable or slightly superior to birds receiving 100 or 121 ppm monensin, although differences were not significant. Ruff et al. (1976) utilized regression procedures to analyze and evaluate possible economic tradeoffs of monensin medication in floor-reared broilers. A similar type analysis which involved severe coccidiosis was made on data from Trials 2 and 3 in the present study. An equation specification of a plausible functional form was selected as giving the best fit if it had the lowest mean square error, conditional upon the rejection of the null-hypothesis that the unknown parameters were equal to zero. The parameter estimates from these equations were in turn used to calculate the implied level of maximum medication effectiveness. No differences in the slopes of the estimated 'relations were found between Trials 2 and 3 for the 8 week body weight and lesion score regression variables. The relationship of 8 week body weight to narasin medication level was implied to be a quadratic function and the maximum weight gain was predicted to occur at
48 ppm narasin. The relationship of total lesion score to level of narasin was implied to be a linear equation at both 7 and 18 days postexposure. The regression coefficients indicated that the total lesion score declined 1.36% or .69% for every additional ppm of narasin at the 7 and 18 days postexposure, respectively. A difference between Trials 2 and 3 in both slope and intercept of a quadratic equation was identified for the 8 week feed conversion relationship. The levels of narasin giving the lowest feed conversion ratio estimate were 80 ppm and 110 ppm in Trials 2 and 3, respectively. These results suggest optimum narasin levels from an economic perspective (Rahn, 1978) would be greater than 48 ppm (predicted
7 DAYS POST EXPOSURE
•
•
17 DAYS POST EXPOSURE
Upper
Mid Lower Ceca
PPM
0 I-
40
60
0
80 100 120 100
NARASIN
-|
tl
I-
40
60
SO 100 120 100
NARASIN
-I
I I
FIG. 1. Pooled lesion scores for 4 regions of the intestine, Trials 2 and 3.
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None Narasin Narasin Narasin Narasin Narasin Monensin Monensin
Level
8 Weeks 2
2012
RUFF ETAL. TABLE 4. Immunity challenge of broilers raised in floor pens, Trial 2* Lesion score 3
Original t r e a t m e n t Drug
Level —(ppm y(caged raised) 0 40 60 80 100 120 100
U
M
L
c
T
3.5a .6 C 1.7 b 2.5b 3.2a 3.6a 3.2a 2.4b
3.6a .yd 1.8 C 2.6b 3.1ab 3.3a 3.1ab 2.9ab
3.1a 3f 6* 8def 1 3de 2 2bc 2 3b 1 5cd
3.1a .4«1 .5" .6cd 1.0cd 1.9 b 1.2bcd 1.4bc
13.3a 2.0e 4.6d 6.5d 8.6 C 11.0b 9.8be 8.2 C
(%) -3.ld 95a 62b 60b 22c icd 12cd 52.5b
n h c (i c f ' ' ' ' ' Values within a column not followed by a common letter are significantly different (P<.05). 1 Control birds were cage raised and never exposed to coccidiosis before challenge. Other birds raised on floor for 8 weeks with medication as indicated. These birds were held in cages for one week prior to challenge and given unmedicated feed. Challenge dose for each species (sporulated oocysts/bird): 1,000,000 E. tenella and E. necatrix-, 200,000 /:'. maxima and E. brunetti, 1,000,000 E. acervulina and E. mivati. 2
Compared with the weight gain of five unchallenged birds of the same original treatment.
3
Severity of coccidiol lesions at 7 days postchallenge; 0 = no lesions, 4 = most severe. Scores shown are those in the upper (U), middle (M), lower (L), or cecal (C) regions and the total lesion score (T).
level of m a x i m u m weight) and less than 95 p p m (the average of the m i n i m u m predicted feed conversion ratios). The results of the i m m u n i t y challenge e x p e r i m e n t indicate that the control of the coccidial infection by all levels of narasin tested was sufficient to prevent maximal development of i m m u n i t y . As indicated by weight gain and lesion score, even levels of 120 p p m narasin allowed s o m e i m m u n i t y to develop based on comparisons of challenge infections in previously u n e x p o s e d cage reared birds. Conversely, even levels as low as 4 0 p p m p r o t e c t e d against the initial immunizing infection to a sufficient degree so that the challenge infection was more severe than that seen in floor birds previously receiving only u n m e d i c a t e d feed. Karlsson and Reid ( 1 9 7 8 ) have previously reported that battery reared broilers i m m u n i z e d with E. tenella were less i m m u n e to challenge infection when the ration contained 80 p p m narasin during the immunizing infection than w h e n the ration was u n m e d i c a t e d . These studies show that the anticoccidial efficacy of narasin previously reported for battery raised birds is also evident in birds reared u n d e r floor pen t y p e conditions. Results also indicate t h a t narasin should prove an effective anticoccidial in field use with activity comparable to t h a t of m o n e n s i n .
ACKNOWLEDGMENTS We t h a n k t h e following people for their assistance during the course of these trials: W. Anderson, H. Danforth, D. Dykstra, J. J o h n s o n , T. Karlsson, R. Major, J. Rasher, P. Smith, and D. Witlock.
REFERENCES James, S., 1978. Coccidial infection in floor pens as a method for the evaluation of anticoccidial drugs. Pages 375—368 in Avian coccidiosis Proc. 13th Poultry Sci. Symp. Brit. Poultry Sci., Ltd., Great Britain. Johnson, J., and W. M. Reid, 1970. Anticoccidial drugs: lesion scoring techniques in battery and floor-pen experiments with chickens. Exp. Parasitol. 28:30-36. Karlsson, T„ and W. M. Reid, 1978. Development of immunity to coccidiosis in chickens administered anticoccidials in feed. Avian Dis. 22:487-495. Rahn, A. P., 1978. Economic evaluation of optimum inclusion rate of monensin in broiler diets. Pages 423—434 in Avian coccidiosis Proc. 13th Poultry Sci. Symp. Brit. Poultry Sci., Ltd., Great Britain. Ruff, M. D., W. M. Reid, J. K. Johnson, and W. K. Anderson, 1979. Anticoccicial activity of narasin in battery raised broiler chickens. Poultry Sci. 58:298-303. Ruff, M. D., W. M. Reid, and A. P. Rahn, 1976.
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Control None Narasin Narasin Narasin Narasin Narasin Monensin
Weight gain
2
NARASIN AND COCCIDIOSIS Efficacy of different feeding levels of monensin in the control of coccidiosis in broilers. Amer. J. Vet. Res. 37:963-967. Ryley, J. F., and R. G. Wilson, 1975. Laboratory studies with some recent anticoccidials. Parasitology 70:203-222.
2013
Weppelman, R. M., G. Olson, D. A. Smith, T. Tamas, and A. van Iderstine, 1977. Comparison of anticoccidial efficacy, resistance and tolerance of narasin, monensin and lasalocid in chicken battery trials. Poultry Sci. 56:1550-1559.
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