Enradin® vs. Avilamycin and Bacitracin - Merck Animal Health

414S C H E R I N G - P L O U G H A N I M A L H E A L T Htechnical services bulletinEnradin ® vs. Avilamycin and Bacitracin: Efficacy (MIC)against C. perfringens and Floor-Reared Broiler PerformanceTwo recent studies have examined the efficacy andfield performance of three growth promotantantibiotics: Enradin ® (enramycin), avilamycin andbacitracin methylene disalicylate. The first study, conductedin Japan, examined the sensitivity of Clostridialperfringens isolates to the three antibiotics. The secondstudy was a controlled floor-pen trial conducted inBrazil and examined weight gain and feed efficiency inbroiler chickens.Study 1 DesignEnradin ® Antimicrobial Feed Additive Efficacyagainst C. perfringensAntibiotic sensitivity studies were routinely conductedon C. perfringens isolated by the Kyodoken laboratory inJapan. Minimum inhibitory concentrations (MICs) weredetermined for broiler isolates obtained by diagnosticlaboratories from 1986 through 2000. Forty-six isolateswere tested in 1986, 183 in 1990, 120 in 1995, 46 in1999 and 173 in 2000. The evolution of MICs forthe isolates from each year are summarized in Figures 1through 3 on the following pages.Results and DiscussionsC. perfringens demonstrated increasing sensitivity toEnradin over the period from 1986 to 2000, butdecreasing or unchanged sensitivity to the otherantibiotics. C. perfringens MICs for Enradin wereconsistently lower than were the MICs for the othertwo antibiotics throughout the time period.Study 2 DesignComparative Performance of Broilers Fed Enradinand other Antibiotic Growth Promoters 1In this study, 1,200 day-old broiler chicks werehoused in a concrete floor house with rice hull litter.The house was divided into 24 pens with 50 chicksper pen. Six randomized pens were assigned to eachof 4 treatment groups with 300 chicks per group.Key PointsMIC testing from 1986 to 2000 shows that the sensitivity of C. perfringens toEnradin ® Antimicrobial Feed Additive was excellent and improving.During the same time, MICs for avilamycin increased, indicating increased resistanceof C. perfringens to this antibiotic. The response to bacitracin did not change.Broilers fed Enradin demonstrated significantly superior feed conversion to bacitracin at21 and 42 days of age.Weights were numerically better for broilers fed Enradin than for those fed avilamycin orbacitracin at 21 and 42 days of age.

Figure 1. C. perfringens Sensitivity to Enradin ® (enramycin)1001986 46 strainsMIC Distribution (%)806040201990 103 strains1995 120 strains1999 46 strains2000 173 strains00 0.05 0.1 0.2 0.39 0.78 1.56 3.13 6.25 12.5 25 50 100MIC (g/mL)Figure 2. C. perfringens Sensitivity to Avilamycin1001986 46 strainsMIC Distribution (%)806040201990 103 strains1995 120 strains1999 46 strains2000 173 strains00 0.05 0.1 0.2 0.39 0.78 1.56 3.13 6.25 12.5 25 50 100MIC (g/mL)

Figure 3. C. perfringens Sensitivity to Bacitracin1001986 46 strainsMIC Distribution (%)806040201990 103 strains1995 120 strains1999 46 strains2000 173 strains00 0.05 0.1 0.2 0.39 0.78 1.56 3.13 6.25 12.5 25 50 100MIC (g/mL)Table 1. Performance of Broilers Raised on Floor and Fed with Antibiotic Growth Promoters1 to 21 Days of Age Control Bacitracin Enramycin Avilamycin CV (%)Weight Gain (g) 848 ab 839 ab 876 a 834 b 2.85 P

TreatmentsT1: Control, no antibiotic growth promoter in feedT2: Bacitracin methylene disalicylate, 27.5 mg/kgT3: Enradin ® (enramycin), 12.5 mg/kgT4: Avilamycin, 10 mg/kgWeight gain, feed consumption and livability weremeasured weekly and at the end of the experimentat 42 days. Feed conversions were calculated at21 and 42 days of age.Results and DiscussionsBroiler chicks fed Enradin demonstrated significantlybetter feed conversion and numerically better weightgain than bacitracin methylene disalicylate at both21 and 42 days of age. Broilers fed Enradin demonstratednumerically better weights and similar feedconversions when compared to avilamycin at both21 and 28 days. Results are summarized in Table 1on the preceding page.SummaryIn Japanese MIC studies, C. perfringens demonstratedincreasing sensitivity to Enradin but decreasing orunchanged sensitivity to two other antibiotics. Inaddition, field trials from Brazil demonstrated superiorperformance in flocks receiving Enradin comparedto avilamycin or bacitracin methylene disalicylate.Worldwide, Enradin has proved to be a highly efficaciousgrowth promotant antibiotic.Reference1Pedroso AA. Performance and organ morphology of broilersfed probiotic or antibiotic and raised in batteries or floorpens. PhD dissertation. Universidade do Estado de SãoPaulo, Brazil. May, 2003.[ Innovative Solutions in Poultry Health ]Copyright © 2006, 2008 Schering-Plough Animal Health Corporation. All rights reserved.Enradin is a registered trademark of Schering-Plough Animal Health Corporation.