Coccidiosis causes dramatic economic losses in the poultry industry. Next to the extensive use of anticoccidial drugs, improving genetic resistance of birds to this parasitic disease represents an attractive alternative. An experiment was run in order to identify lines of chickens resistant and susceptible to coccidiosis as a tool to search for genetic markers of resistance. Five outbred lines were used: two Egyptian lines (Mandarah and Fayoumi), a Rhode Island Red line, and two White Leghorn lines (WLB21 and WLDW). The WLDW line segregated for three MHC haplotypes, B15, B19, and B21, and for the sex-linked dwarf gene, DW. Chicks were challenged at 4 wk of age with a high dose of Eimeria tenella (150,000 oocysts) and slaughtered 8 d postinoculation. Innate resistance was assessed individually by measures of lesion score, mortality, and body weight gain at slaughter, and plasma coloration 4 d postinoculation. Large differences in resistance to E. tenella were observed between lines. The Fayoumi line appeared clearly as the most resistant line, showing no mortality, less severe lesions than other lines, and a 30% reduction of growth as compared to control birds. The WLDW line was the most susceptible, with 27% mortality and a 85% reduction in growth. No major effect of MHC or dwarfism on resistance to E. tenella was found.

Summary Contamination of a hatchery by Aspergillus fumigatus has been studied for 8 weeks from eggs to day old chicks. We have shown that the contamination of the hatchery originates on the egg shell and that each time the eggs are manipulated, spores of Aspergillus fumigatus are thrown into suspension in the air. Thus it seems necessary to bring eggs with as few as possible spores of Aspergillus fumigatus on their shell into the hatchery. Prophylaxis of aspergillosis should be foreseen from the conception of the hatchery: the ventilation system and the internal lay‐out should be designed to prevent dispersion and accumulation of Aspergillus fumigatus spores during the processing of the eggs through the hatchery.

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Le but de cette enquête est de mettre au ·point une méthode de travail permettant d'éviter les pertes économiques liées aux coccidioses cliniques.Au cours des années 1976 et 1977, le nombre d'ookystes présents dans les fécès de poulets de chai.r âgés de 4 semaines est contrôlé sur 608 bandes.D'autres critères pouvant également influencer les résultats zootech niques et le niveau d'infection coccidienne sont enregistrés : croissement commercial de poulets de chair, densité au m2, sensibilité des ookystes aux anticoccidiens.La corrélation entre les résultats zootechniques et les critères précités, étudiée par l'analyse factorielle des correspondances, a permis de mettre en évidence que: -le nombre d'ookystes présent dans les fécès est indépendant des croissements commerciaux ; -fa forte densité des animaux au m2 tend à accroître • le nombre de bandes de poulets de chair contaminés et à réduire les résultats zootechniques ; -fa perte d'activité des anticoccidiens entraîne une diminution des résultats zootechniques et une augmentation à la fois du nombre d'ookystes chez les animaux âgés de 4 semaines et du nombre de bandes de poulets de chair contaminés; -50 000 ookystes sont sans influence sur les résultats zootechniques quand aucun stress ne perturbe les animaux, mais ils peuvent entraîner une coccidiose clinique dans Je cas contraire. Mots clésEnquête -Poulets de chair -Relation entre ookystes et coccidiose clinique. BULLETIN DE L'ACADÉMIE SUMMARYThe aim of this enquiry was to establish a method to prevent clinical coccidiosis in broiler bouses. 1976 and 1977), the number of oocyst per 4 of fresh faeces were estimated in 608 four week-old broiler crops. During two years (inOther data which can have an effect both upon the performance and the number of oocysts in the faeces were recorded: broiler strains, density, sensibility to anticoccidial drugs.The connexion beetween the performance and these data, studied by the cAnall yse factorielle des correspondances» have shown the following:-the number of oocysts/g of faeces is not linked to the broiler strains; -the number of contamined broiler fots increases with the density as the bad results; -the resistance ac:quired to anti coccidial drugs decreases the per formance and increases the number of oocyst in crops and the number of contaminated crops; -normally 50 000 oocysts have not an effe.ct upon the zootechnical results, but if some st· ress happens in the broiler units a clinical coccidiosis may appear.

RésuméDes poussins des races Fayoumi, Rhode-Island et