Evidence-Based Consideration of Dietary ‘Alternatives’ to Anticoccidial Drugs to Help Control Poultry Coccidial Infections

Coccidiosis remains a major disease and economic challenge for the global poultry industry. Coccidiosis in chickens is caused by seven Eimeria species that target specific regions of the gastrointestinal tract and cause malabsorptive or haemorrhagic disease. These Eimeria species infect segment-specific epithelial cells and thus need to navigate the host’s indigenous microbiome and intestinal defences to establish an infection and cause disease. Good husbandry practices, prophylactic use of anticoccidial drugs and/or live parasite vaccination have been the primary control measures employed but there are challenges with vaccination and growing constraints on anticoccidial drug use. This review, therefore, considers available information on the key steps of the infection process, notable microbiome- or host-related changes occurring, and the (potential) influence of dietary ‘alternatives’ to anticoccidial drugs. There is good available evidence to indicate that some phytogenics, prebiotics, probiotics, betaine, n-3 fatty acids, as well as carbohydrase enzymes and anti-IL-10 antibodies, can (beneficially) modulate at least some of these features in coccidiosis-specific challenge studies. As a minimum, these anticoccidial drug ‘alternatives’ could support the establishment of a desirable host microbiome and optimum immune system development. It is important to better understand the potential of these ‘alternatives’ in commercial production and how they can complement, or reduce, the use of anticoccidial drugs.