Contributed Papers: Oral Presentations
Vaccines

Effects of dietary short chain fatty acids on experimentally induced coccidiosis and necrotic enteritis in broilers vaccinated against coccidiosis


S. Perrucci (1), G. Brajon (2), G. Fichi (1), G. Rossi (3), M. Kang (4), F. Corrias (2), A. Piazza (2), A. Buccioni (5), F. Petacchi (5), G. Tosi (6), M. Antongiovanni (5)
(1) Dipartimento di Patologia Animale, Profilassi ed Igiene degli Alimenti, University of Pisa (Italy);
(2) Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana – Sezione di Firenze (Italy);
(3) Dipartimento di Scienze Veterinarie, University of Camerino (Italy).
(4) Department of Veterinary Medicine, University of Qinghai (China);
(5) Dipartimento di Scienze Zootecniche, University of Florence (Italy).
(6) Istituto Zooprofilattico Sperimentale per La Lombardia e l’Emilia Romagna – Sezione di Forlì (Italy).
Corresponding author’s E-mail: perrucci@vet.unipi.it

 

Introduction
In the poultry industry, necrotic enteritis (NE) manifests itself when a large Clostridium perfrigens (CP) colonization coincides with significant damages to the gut epithelium, often caused by coccidia. Since antibiotics and coccidiostats are to be banned in the European Union next year, short chain fatty acids (SCFA) could replace them.
Objective. The aim of the present work was to verify the onset of experimentally induced NE in vaccinated chickens (Paracox-5, sprayed in the hatchery), either fed SCFA for 21 days only or avilamycin for 42 days.
Birds were orally challenged on day 21 with CP (5x105 CFU/ml) and Eimeria acervulina, maxima and tenella (104; 103 and 5x103 oocysts, respectively). The groups (40 chickens each) were: 1) control; 2) avilamycin, 10 ppm; 3) butyric triglyceride (BT), 0.2%; 4) BT, 0.2% + caprylic and capric triglycerides, 0.15% and 5) BT, 0.2% + free caprylic and capric acids, 0.1%.
From day 28 until day 42, three birds per group were euthanised each week and their intestines examined for coccidia, CP, NE lesions, and number of oocysts for gram of faeces (OPG).
Main findings. All the examined birds presented NE lesions after Eimeria spp. and CP. The lesion score was higher in the first two weeks following infection, and no mortality was recorded. The most severe lesions were associated with a high degree of sub-epithelial/interstitial coccidian colonization. Clostridia, when largely present, were associated with necrotic material or into severely damaged crypts. OPG resulted highest with avilamycin at day 28.
Conclusions. Although vaccinated, all the birds developed gut coccidian lesions and NE. Avilamycin was linked with a high number of coccidian OPG. The birds fed diet 4 had better live performances.