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Efficacy of Tylan and Monteban for Treatment and Control of Clostridial Enteritis in Broiler Chickens

Dr. John Brennan

Research Manager

Shur-Gain Agresearch,

Canada

Summary

A pure culture challenge model was successfully used to reproduce necrotic enteritis (NE) mortality, gross lesions and clinical signs in broiler chickens raised in floor pens. Administration of 50, 100, 150 or 300 ppm dietary Tylan for seven consecutive days following confirmation of an NE outbreak reduced (P<0.05) NE mortality and lesion score and improved (P<0.05) overall growth and feed efficiency of broiler chickens. Optimum Tylan dose for control of NE was 100 ppm. A second floor pen study evaluated the efficacy of 70 ppm dietary narasin (Monteban) as an aid in prevention of NE in challenged broiler chickens. Narasin fed continuously from day 0 to 41, reduced (P<0.05) total NE mortality of challenged broilers and improved (P<0.05) overall growth and feed efficiency. A third floor pen study evaluated the efficacy of 70 ppm dietary narasin (Monteban) and 55 ppm BMD as aids in prevention of NE in challenged broiler chickens. Narasin and BMD reduced (P<0.05) total NE mortality of challenged broilers and improved growth and feed efficiency.

Introduction

Necrotic enteritis (NE) of domestic broiler chickens was first described by Parish in 1961(Ficken and Wages, 1997). The disease is caused by Clostridium perfringens, types A (Long and Truscott, 1976) and C (Shane et al., 1985). The organism is readily grown on blood agar plates incubated anaerobically at 37C and produces a characteristic inner zone of hemolysis. Clinical signs of the disease in broiler chickens include depression, anorexia, reluctance to move, ruffled feathers and diarrhea. In experimental reproduction of the disease, the first mild clinical signs are evident approximately 24 to 36 hours after administration of a pure C. perfringens culture to broiler chickens in floor pens. These signs include moderate feed intake suppression and huddling of birds in small groups of approximately 3 to 10 birds. As the disease progresses, feed intake suppression increases, the most severely affected birds become reluctant to move and mortality commences. Gross lesions occur primarily in the small intestine, especially the jejunum and ileum and may range from focal to extensive necrosis with little or no evidence of hemorrhage.

Reproduction of Necrotic Enteritis in Broiler Chickens

Long and Truscott (1976) used a pure culture challenge model to reproduce NE in broiler chickens. A C. perfringens broth was added to sterilized feed at 1.25:1 (w:v) to obtain 107 C. perfringens per gram of feed. Total NE mortality ranged from 1.0 to 28% and peaked approximately 48 hours after introduction of inoculum. This model was later modified to include elevated dietary concentration of fishmeal prior to initiation of inoculum administration and intra-duodenal administration of inoculum (Truscott and Al-Sheikhly, 1977; Vissiennon et al., 2000). Disruption of the normal small intestinal mucosa appears to facilitate establishment and growth of C. perfringens. Infection of broilers with Eimeria acervulina prior to administration of a C. perfringens challenge, markedly increased NE mortality (Al-Sheikhly, F. and Al-Saieg, A., 1980). Elevated concentration of dietary wheat (Branton et al., 1987), zinc (Baba et al.,1992) and fishmeal (Truscott and Al-Sheikhly, 1977) may also exacerbate C. perfringens-induced NE but modes of action remain unclear.

Suitable models are required to conduct controlled studies of product efficacy for control or treatment of NE. Pure culture (C. perfringens) challenge models are generally used but in the absence of dietary or other enteric disease stressors, mortality is often low and variable. Therefore, dietary or disease stressors are employed to increase NE mortality and gross lesions. At Shur-Gain Agresearch, a pure (C. perfringens) culture challenge model has been used successfully in NE studies (Brennan et al., 1996; Brennan and Cheng, 1997; Skinner and Brennan, 1999; Brennan et al., 2000a; Brennan et al., 2000b). A randomized complete block design is used with N treatments and approximately 6 to 10 replicate location blocks.

Day-old birds are randomly assigned to floor pens, each containing 50 birds on day of placement. Typical commercial diets, bird management and lighting program are used with the exception of a high protein diet which is fed for several days prior to introduction of inoculum on day 14. Inoculum containing approximately 107 cfu C. perfringens per mL is typically administered ad libitum via feed from days 14 to 16 inclusive. Throughout the challenge period, daily feed consumption is recorded. Randomly selected birds from each pen are euthanized using CO2 gas on day 17. These birds are scored for coccidiosis lesions (Johnson and Reid, 1970) and evaluated for gross NE lesion score using the following scale (Prescott et al., 1978):

Score Description
0 Normal, no evidence of gross lesions
1 Thin, friable small intestine
2 Focal necrosis and/or ulceration
3 Patchy necrosis
4 Severe extensive necrosis (typically seen in birds which have died from NE)

All mortality is subjected to gross necropsy. Small intestinal segments are collected from each mortality and isolation of C. perfringens is attempted. Typical primary and secondary decision variables are as follows:

1. Primary: NE mortality (gross diagnosis confirmed by positive C. perfringens culture), % of birds placed.

2. Secondary: NE lesion score; Clinical score; Daily feed intake during the challenge period; Final bodyweight; Overall feed efficiency. The pen is considered the experimental unit. Therefore, pen means are calculated for primary and secondary variables and these are subjected to analysis of variance. Reproduction of NE without coccidiosis co-infection permits the study of treatment effects on Clostridium perfringens-induced enteritis without the potential confounding influence of treatment effects on coccidiosis. The model can be readily adapted to the study of control or treatment of NE outbreaks. It is very suitable for the study of ionophore efficacy for control of NE (Brennan and Cheng, 1997).

 

Dietary Tylan as a Treatment for Necrotic Enteritis

The effects of dietary Tylan on mortality, intestinal lesion scores and growth performance of Clostridium perfringens-challenged broiler chickens were evaluated in a floor pen study (Brennan et al., 2000b). A randomized complete block design was used to study the effects of administration of 0, 50, 100, 200 or 300 ppm dietary Tylan for seven consecutive days following confirmation of a necrotic enteritis outbreak. Each floor pen contained 25 male and 25 female birds on day of placement (Day 0). There were eight replicate location blocks in the study. The challenge was administered via feed on Days 14 to 16 inclusive. An NE outbreak was confirmed based on NE mortality and the presence of gross lesions in randomly selected birds on Day 15. Medicated diets were introduced on Day 15 and fed for seven consecutive days. On Days 17 (Treatment day 2) and 22 (Treatment day 7), four birds per pen were randomly selected, sacrificed and scored for NE lesions on a scale of 0 (normal) to 4 (extensive necrosis). The study ended on Day 29.

Treatment effects on NE mortality and lesion score are summarized in Table 1. In Tables 1 to 5, means not sharing one or more common superscripts are significantly (P<0.05) different. NE mortality was significantly (P<0.05) reduced by all medication levels in comparison to the non-medicated controls. On Day 17, approximately 48 hours after introduction of medication, mean NE lesion score was significantly (P<0.05) reduced to 1.41 in response to 50 ppm Tylan and was further reduced (P<0.05) to 0.38 in response to 100 ppm Tylan.

There was no evidence of NE lesions in birds fed 200 or 300 ppm Tylan for approximately 48 hours. Mean NE lesion scores were markedly lower on Day 22 but the overall response to medication level was similar to the Day 17 data. Based on mortality and lesion score data, optimum Tylan dose for treatment of an NE outbreak was 100 ppm.Final (Day 29) bodyweight, overall feed efficiency and feed intake were all significantly (P<0.05) improved in response to 50, 100, 200 or 300 ppm dietary Tylan administered for 7 consecutive days following confirmation of the NE outbreak (Table 2).

Table 1: Tylan effect on NE mortality and lesion score
Tylosin phosphate (ppm) NE mortality Day 17 Day 22
(%of birds placed)
Days 15-29 (Treatment day 2)
mean lesion score
(Treatment day 7)
mean lesion score
0 3.25a 2.66a 0.63a
50 0.00b 1.41b 0.32a,b
100 0.25b 0.38c 0.06a,b
200 0.50b 0.00d 0.06a,b
300 0.25b 0.00d 0.00b

NE mortality was significantly (P<0.05) reduced by all medication levels in comparison to the non-medicated controls. On Day 17, approximately 48 hours after introduction of medication, mean NE lesion score was significantly (P<0.05) reduced to 1.41 in response to 50 ppm Tylan and was further reduced (P<0.05) to 0.38 in response to 100 ppm Tylan. There was no evidence of NE lesions in birds fed 200 or 300 ppm Tylan for approximately 48 hours. Mean NE lesion scores were markedly lower on Day 22 but the overall response to medication level was similar to the Day 17 data. Based on mortality and lesion score data, optimum Tylan dose for treatment of an NE outbreak was 100 ppm. Final (Day 29) bodyweight, overall feed efficiency and feed intake were all significantly (P<0.05) improved in response to 50, 100, 200 or 300 ppm dietary Tylan administered for 7 consecutive days following confirmation of the NE outbreak (Table 2).

Table 2: Tylan effect on bodyweight and feed efficiency
Tylosin phosphate (ppm) Day 29 bodyweight, kg Feed efficiency
(feed/bodyweight gain)
Daily Feed Intake
(Day 0-29), gram
0 1.020a 1.740a 55a
50 1.141b 1.642b 60b
100 1.160b 1.629b,c 61b
200 1.164b 1.607c 59b
300 1.157b 1.630b,c 60b

Daily feed intake of challenged medicated birds increased in an approximately linear manner during the three-day challenge period (Figure 1). On the second day of inoculum administration, feed intake was significantly (P<0.05) increased in response to all Tylan dose levels. Feed intake of medicated birds continued to accelerate on the third day while intake of non-medicated controls was markedly reduced. The pattern of feed intake reduction observed in non-medicated birds on the second and third days following initiation of challenge suggests that early diagnosis of NE is essential for effective in-feed treatment. However, the results of this study indicate that 100 ppm dietary Tylan is a very effective treatment for C. perfringens-induced NE in broiler chickens.

Figure 1: Dietary Tylan effect on daily feed intake of challenged broilers

Additional studies are in progress to evaluate Tylan Water Soluble as a treatment for NE. Efficacy of Monteban (narasin) for Prevention of Necrotic Enteritis Mortality The effects of dietary Monteban (70 ppm narasin) on mortality, intestinal lesion scores and growth performance of Clostridium perfringens-challenged broiler chickens were evaluated in a floor pen study. A randomized complete block design was used to study the effects of continuous administration of 0 or 70 ppm dietary narasin on non-challenged or challenged broiler chickens. There were 40 floor pens each containing 50 same-sex birds on Day 0. The challenge was administered via feed on days 14 to 16 inclusive. Medicated diets were introduced on Day 0 and fed continuously to Day 41. On Day 17 two birds per pen were randomly selected, sacrificed and scored for NE lesions on a scale of 0 (normal) to 4 (extensive necrosis). The study ended on Day 41.

Some NE mortality was observed in non-challenged birds and this is expected in response to the high protein diet fed prior to day 14. Total NE mortality of challenged non-medicated birds was 5.98% and was significantly reduced (P<0.05) to 1.80% by dietary narasin (Table 3).

Narasin reduced mean NE lesion score from 2.05 to 1.70 but this was not statistically significant.

Table 3: Effect of narasin on NE mortality and lesion score of challenged and non-challenged broiler chickens
Challenged Medication NE mortality
(% of birds placed)
Day 17 mean
lesion score
No Non Medicated 1.20a 0.25a
Yes Non Medicated 5.98b 2.05b
No 70 ppm narasin 0.20a 0.00a
Yes 70 ppm narasin 1.60a 1.70b

In the absence of medication, the C. perfringens challenge significantly (P<0.05) reduced Day 21 bodyweight from 0.632 kg to 0.549 kg. Narasin significantly improved (P<0.05) bodyweight and feed efficiency of challenged broilers on Days 21 and 41 (Table 4; Table 5).

Table 4: Effect of narasin on NE Day 21 bodyweight and feed efficiency of challenged and non-challenged broiler chickens
Challenged Medication Bodyweight, kg Feed efficiency
No Non Medicated 0.632a 1.379a
Yes Non Medicated 0.549b 1.519b
No 70 ppm narasin 0.654c 1.331c
Yes 70 ppm narasin 0.604d 1.448d

 

Table 5: Effect of narasin on NE Day 41 bodyweight and feed efficiencyc of challenged and non-challenged broiler chickens
Challenged Medication Bodyweight, kg Feed efficiency
No Non Medicated 1.805a 1.963a
Yes Non Medicated 1.767a 1.951a
No 70 ppm narasin 2.015b 1.830b
Yes 70 ppm narasin 1.907c 1.875c

On the first day of the challenge period there was no significant (P>0.05) effect of narasin on feed intake of challenged broilers (Figure 2). However, feed intake of non-medicated birds was significantly (P<0.01) reduced to 50-58 grams per day thereafter while birds fed narasin maintained a feed intake of 69 to 70 grams. These data were consistent with narasin’s effect on NE mortality and clinical signs.

Figure 2: Dietary narasin effect on daily feed intake of challenged broilers

 

In summary, dietary narasin reduced NE mortality (P<0.05), improved feed intake during the challenge period (P<0.01) and improved final bodyweight and overall feed efficiency. Vissiennon et al. (2000) also reported substantial reductions in NE mortality in response to prophylactic administration of narasin. Their model was based on repeated intra-duodenal administration of C. perfringens which resulted in NE mortality of 36% in non-medicated controls. Therefore, comparison with the present study is difficult.

Comparative Efficacy of Monteban (narasin) and BMD for Prevention of Necrotic Enteritis Mortality

A total of 40 floor pens were used to study the effects of dietary narasin (70 ppm) and BMD (55 ppm) on NE mortality, lesion score and growth of C. perfringens–challenged broiler chickens (Skinner and Brennan, 1999). NE mortality of challenged non-medicated birds was 4.7% and was significantly (P<0.05) reduced to 1.1%, 0.3% and 0% by narasin, BMD and narasin plus BMD, respectively (Figure 3). Narasin significantly (P<0.05) improved overall growth and feed efficiency (Table 6).

Figure 3: Narasin and BMD effects on NE mortality, %

I: Infected by oral admission of C. perfringens on Day 14-16
Narasin: Continuous (Day 0-41) administration of 70 ppm dietary narasin
BMD: Continuous (Day 0-41) administration of 55 ppm dietary BMD

Conclusions

Administration of dietary Tylan for seven consecutive days following confirmation of an NE outbreak reduced (P<0.05) NE mortality and lesion score and improved (P<0.05) overall growth and feed efficiency of broiler chickens. The optimum dose of Tylan for control of NE was 100 ppm. Narasin fed continuously from Day 0 to 41, reduced (P<0.05) total NE mortality of challenged broilers and improved (P<0.05) overall growth and feed efficiency.

Table 6: Narasin and BMD effects on overall (Day 41) growth and feed efficiency of broiler chickens
Challenged Medication Bodyweight Gain, kg/bird/day Feed efficiency
No Non Medicated 0.049b 1.957ab
Yes Non Medicated 0.048b 2.017a
Yes 70 ppm narasin 0.051a 1.919b
Yes 55 ppm BMD 0.053a 1.981a
Yes 70 ppm narasin plus 55 ppm BMD 0.053a 1.900a

References

Al-Sheikhly, F. and Al-Saieg, A. 1980. Role of coccidia in the occurrence of necrotic enteritis of chickens. Avian Diseases 24:324-333.

Baba, E., Fuller, A., Gilbert, J., Thayer, S. and McDougald, L. 1992. Effects of Eimeria brunetti infection and dietary zinc on experimental induction of necrotic enteritis in broiler chickens. Avian Diseases 36:59-62.

Branton, S.L., Reece, F.N. and Hagler, W.M. 1987. Influence of a wheat diet on mortality of broiler chickens associated with necrotic enteritis. Poultry Science 66:1326-1330.

Brennan, J.J. and Cheng, T. 1997. Efficacy of lasalocid for prevention of necrotic enteritis in broiler chickens. In: Proc. VIIth International Coccidiosis Conference–Control of Coccidiosis into the Next Millenium. Sept. 1-5, Keble College, Oxford University, England.

Brennan, J.J., Horne, M., Wilson, J. and Barnum, D.A. 2000a. Efficacy of bacitracin methylene disalicyclate fed in combination with diclazuril for prevention of necrotic enteritis in broiler chickens. 89th meeting Poultry Science Assoc., Montreal, Canada (abst.).

Brennan, J.J., Moore, G., Poe, S., Vessie, G., Wilson, J., Barnum, D.A., Zimmerman, A. and Dick, P. 2000b. Efficacy of dietary tylosin phosphate (Tylan) for control of necrotic enteritis in broiler chickens. 89th meeting Poultry Science Assoc., Montreal, Canada (abst.).

Brennan, J.J., J. Radu, D.A. Barnum, D. Carrier, J. Kelly and B. Kilmer. 1996. Efficacy of zinc bacitracin and bacitracin methylene disalicyclate for prevention of necrotic enteritis in broiler chickens. Poultry Science 75 (Suppl. 1):283.

Ficken, M.D. and Wages, D.P. 1997. In: Diseases of Poultry 10th Edition. 1997. Iowa State Press, Ames, pp. 261-264.

Johnson, J. and Reid, W. 1970. Anticoccidial drugs: Lesion scoring techniques in battery and floor-pen experiments with chickens. Experimental Parasitology 28:30-36.

Long, J.R. and Truscott, R.B. 1976. Necrotic enteritis in broiler chickens III. Reproduction of the disease. Can. J. Comp. Med. 40:53-59.

Prescott, J., Sivendra, R. and Barnum, D.A. 1978. The use of bacitracin in the prevention and treatment of experimentally-induced necrotic enteritis in the chicken. Can. Vet. J. 19:181-183.

Shane, M., Gyimah, J.E., Harrington, K.S. and Snider, T.G. 1985. Etiology and pathogenesis of necrotic enteritis. Vet. Res. Comm. 9:269-287.

Skinner, J. and Brennan, J. 1999. Efficacy of bacitracin methylene disalicyclate fed in combination with narasin for prevention of necrotic enteritis. Poultry Science 78 (Suppl. 1):129.

Truscott, R.B. and Al-Sheikhly, F. 1977. Reproduction and treatment of necrotic enteritis in broilers. Am. J. Vet. Res. 38(6):857-861.

Vissiennon, T., Kroger, H. and Kliche, R. 2000. Effect of avilamycin, tylosin, and ionophore anticoccidials on Clostridium perfringens enterotoxemia in chickens. Berl. Munch. Tierarztl. Wschr. 113:9-13.

Biography

John Brennan was born and educated in Ireland. He obtained a Ph.D. in animal nutrition from the University of Alberta in 1986 and was a Research Scientist in the R & D department of Shur-Gain animal nutrition and health (now a member of Maple Leaf Foods, Inc.) from 1986-1992. In 1993, he was appointed Research Manager at Shur-Gain Agresearch, Canada’s largest animal and poultry contract research facility. John has been an Investigator in numerous clinical studies submitted to Canadian, US an EU regulatory authorities. Development and use of enteric and other disease challenge models in poultry and swine has been a major focus of his research over the past six years. Shur-Gain Agresearch conducts regulatory (GCP; GLP) and non-regulatory studies for the world’s leading suppliers of animal health and nutrition products.