EFFECTS OF ANTIBIOTIC PROPHYLAXIS ON THE PERFORMANCE AND GUT MICROBIOTA OF GROWING BROILER CHICKS

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1 EFFECTS OF ANTIBIOTIC PROPHYLAXIS ON THE PERFORMANCE AND GUT MICROBIOTA OF GROWING BROILER CHICKS Alexandra Tonks Supervisors: Dr Caroline Rymer, Prof Martin Woodward School of Agriculture, University of Reading, UK 1

2 WHY STUDY CHICKEN MICROBIOTA? 50 years ago = today = Further enhancement of production efficiency by selection of elite gut microbiota?... the future? =? 2

3 ANTIBIOTICS IN BROILER PRODUCTION Routine use at sub-therapeutic levels Prevention > cure Reduced inflammation Increase in food security 9% 7% 15% 70% Antibiotic prophylaxis decreases feed conversion ratio (FCR) Livestock: non-therapeutic Livestock: therapeutic Human: therapeutic Other Increase in resistance EU ban of AGP in Source: Keep Antibiotics Working Coalition

4 MICROBIOME AND PERFORMANCE Ruminococcaceae Lachnospiraceae Short chain fatty acids (SCFA): Acetate Propionate Butyrate Increased uptake of nutrients: Proliferation of enterocytes Increased villus height Reduced incidence of disease: Increased epithelial integrity Reduced inflammation 4

5 LIVE CHICKEN TRIAL: DECEMBER Ross 308 broiler chicks: 3x2 arrangement of treatments Antibiotic prophylaxis Linco-spectin D1-3 Lincomycin: Target: G+ve bacteria (Streptococcus) Mechanism: binds to 50S ribosomal subunit Spectinomycin: Target: G-ve bacteria (Proteobacteria) Mechanism: binds to 30S ribosomal subunit 5

6 Live weight (g) FCR EFFECTS OF LINCO-SPECTIN ON PERFORMANCE 1400 Live weight * 1,65 FCR , * 1,55 1, * 1,45 1, ** * Bird age (days) CON AB 1,35 1, Bird age (days) CON AB Reduction at all points P<0.05 at day 4 No significance 6

7 16S SEQUENCING DNA extracted from caecal content normalised for comparisons Ilumina sequencing target: 16S ribosomal subunit (subunit of 30S) dntps added sequentially incorporation = fluorescence Variable regions are unique to bacterial groups, species etc Comparison of sequences to ribosomal database Allocation and relative quantification of bacterial identities 7

8 Relative abundance (%) EFFECT OF TREATMENT ON MICROBIOME Linco-spectin altered the profile of the caecal microbiome at all points 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Effects of treatment on microbiome: Day 15 CON Butyrate producers Treatment AB Other Lactobacillaceae Clostridiales other Lachnospiraceae Ruminococcaceae Erysipelotrichaceae Alcaligenaceae Enterobacteriaceae 8

9 Relative abundance (%) Relative abundance (%) EFFECTS OF LINCO-SPECTIN ON BUTYRATE PRODUCERS 60 Ruminococcaceae 60 Lachnospiraceae Bird age (days) Bird age (days) CON AB CON AB Significance at day 15 (P = 0.050) Significance at day 29 (P = 0.035) 9

10 Relative abundance (%) EFFECTS OF LINCO-SPECTIN ON BUTYRATE PRODUCERS Bird age (days) CON AB Significance at day 9 when combined (P = 0.045) No significance at day 29 10

11 CONCLUSIONS Decrease in LW following administration of Linco-spectin: Unnecessary no diseased birds? Shifts in microbial profile Significant differences in butyrate producers: Reduction in butyrate - effects on ability to utilise feed? Increase understanding of interactions between host/bacteria: Enhancement of certain species Reduction in antimicrobial resistance probiotics? Increase in performance = decrease in production costs 11

12 ACKNOWLEDGEMENTS Supervision and technical insight: Dr Caroline Rymer (School of Agriculture) Prof Martin Woodward (Food and Nutritional Sciences) Richard Ellis (Animal and Plant Health Agency) Experimental setup: Centre for Dairy Research, University of Reading Funding: MERCK 12

13 MANY THANKS FOR YOUR ATTENTION QUESTIONS ARE WELCOME 13