Quantifying the effect of coccidiosis on broiler performance and infection outcomes in the presence and absence of control methods

• Published in: Poultry science 2022-04, Vol.101 (4), p.101746-101746, Article 101746
• Main Authors: Taylor, James, Walk, Carrie, Misiura, Maciej, Sorbara, Jose-Otavio Berti, Giannenas, Ilias, Kyriazakis, Ilias
• Format: Article
• Language: English
• Subjects: Animals; broiler; Chickens; coccidiosis; Coccidiosis - drug therapy; Coccidiosis - prevention & control; Coccidiosis - veterinary; Eimeria; IMMUNOLOGY, HEALTH AND DISEASE; Ionophores; meta-analysis; Oocysts; Poultry Diseases - pathology
• ISSN: 0032-5791; 1525-3171
• DOI: 10.1016/j.psj.2022.101746

A systematic review and meta-analysis was conducted to investigate the role of Eimeria species, dose and inoculation time, on performance and infection outcomes of different broiler strains infected for different study durations. The meta-analysis addressed E. acervulina, E. maxima, E. tenella, and mixed species infections, and involved data from 72 peer-reviewed articles, corresponding to 521 treatments performed on 20,756 broilers. A secondary objective was to investigate the effects of synthetic anticoccidials, ionophores, and vaccination against Eimeria on the above outcomes. Performance during infection was scaled (%) to that of the uninfected birds. Infection reduced scaled ADFI and ADG (P < 0.001) and increased feed conversion ratio (FCR; P < 0.05); there was a significant interaction between dose and species on scaled ADFI and ADG, suggesting that different species affected these variables to different extents (P < 0.001). There was a tendency for an interaction between dose and broiler strain on scaled ADFI (P = 0.079), and a significant interaction between these variables on scaled ADG (P < 0.01). A tendency for an interaction between oocyst dose and Eimeria species (P = 0.067) on maximum number of oocysts excreted was observed. Lesion scores were significantly affected by dose, species, and their interaction (P < 0.05), the latter caused by an increase in the lesion scores during E. maxima and E. tenella infections. Control methods significantly affected scaled ADG and FCR (P < 0.05) and there was an interaction between dose and control methods on ADFI (P < 0.001). Synthetic anticoccidial use improved scaled ADG (P < 0.01), whereas ionophores improved FCR compared with untreated birds (P < 0.01). An interaction between dose and control method on scaled ADFI was caused by the higher ADFI of vaccinated compared to untreated birds, as dose increased. There was a significant effect of control methods on lesion scores (P < 0.01). All findings advance our understanding of the factors that influence the impact of coccidiosis and its controls in broilers.