Comparison Between a Live, Attenuated Anticoccidial Vaccine and an Anticoccidial Ionophore, on Performance of Broilers Raised with or without a Growth Promoter, in an Initially Eimeria-Free Environment

Abstract

An experiment was carried out to study the effects of vaccination with Paracox®, a live, attenuated vaccine against avian coccidiosis, on broilers isolated from extraneous Eimeria parasites. The study involved 3200 broiler chickens raised in floor pens similar to commercial conditions, but in an initially Eimeria-free environment. Forty percent of the chickens were vaccinated at 3 days of age and given either a basal unmedicated feed or a feed supplemented with the feed antibiotic virginiamycin. Unvaccinated birds were given either the basal feed or feed supplemented either with virginiamycin or the anticoccidial ionophore narasin. At slaughter at 36 days of age vaccinated birds had a lower live weight than non-vaccinated birds. The difference was 4.6% in unmedicated, and 6.0% in virginiamycin medicated chickens. Feed conversion ratio at slaughter was 2.5% higher for unmedicated vaccinated birds, and 1.3% higher for virginiamycin medicated vaccinated birds, compared to respective non-vaccinated groups. There was no significant difference in overall performance of unvaccinated birds given narasin as compared to virginiamycin. At 10 days post vaccination vaccinated birds had a higher number of Clostridium perfringens in the caeca, but there was no difference thereafter. Throughout the experiment, caecal clostridial counts were considerably higher in vaccinated unmedicated birds than in unvaccinated birds given narasin. The number of oocysts shed in the vaccinated groups was very low, but during a subsequent challenge with E. maxima and E. tenella the birds’ immunity was found to be satisfactory.

Sammanfattning

Effekterna av vaccinering med Paracox®, ett levande, attenuerat vaccin mot koccidios hos fjäderfä, studerades hos 3200 slaktkycklingar. Kycklingarna foddes upp på golvströbädd i en miljö fri från naturliga koccidier. Fyrtio procent av kycklingarna vaccinerades oralt via dricksvattnet vid 3 dagars ålder. Vaccinerade kycklingar fick antingen ett basfoder (12,0 MJ/kg, 19,7% råprotein) utan tillsatser (B), eller med tillsats av 20 mg virginiamycin/kg (V). Ovaccinerade kycklingar fick antingen foder B, foder V eller basfodret med tillsats av koccidiostatika (narasin 70 mg/kg) (N). Vid slakt vid 36 dagars ålder var de vaccinerade kycklingarnas levande vikt lägre än de ovaccinerades (4,6% för foder B och 6,0% för foder V). Även foderomvandlingsförmågan (kg foder/kg levande vikt) var sämre hos de vaccinerade kycklingarna (2,5% för foder B och 1,3% för foder V). Det var ingen skillnad i produktions- och hälsohänseende melIan kycklingar som fått foder V eller N. Antalet Clostridium perfringens i blindtarmarna var högre hos vaccinerade djur 10 dagar efter vaccinationen, men därefter påverkade vaccineringen inte förekomsten av dessa bakterier. De vaccinerade kycklingarna utsöndrade endast små mängder oocystor. Experimentell inokulering vid 37 dagars ålder av en mindre grupp kycklingar visade art en tillfredsställande immunitet hade utvecklats.