ARTICLE 68 FEED & ADDITIVE MAGAZINE November 2025 While severe outbreaks can lead to mortality, even subclinical infections reduce nutrient absorption, slow growth, and impair feed conversion. They also predispose birds to secondary conditions such as necrotic enteritis (Blake et al., 2020). This economic burden extends across the poultry value chain— from farmers to processors—making effective prevention a priority (Figure 1 and 2). 2. LIMITS OF DRUGS AND VACCINES Coccidiosis management has traditionally relied on four approaches: farm management, synthetic drugs, vaccines, and natural products. Each has its merits but also significant limitations. • Farm management: Litter replacement and disinfection reduce contamination but cannot fully eliminate resilient oocysts. • Synthetic drugs: Once reliable, these now face widespread resistance and regulatory withdrawal constraints (Chapman, 2014). • Vaccines: Effective in principle but costly, and require repeated reinfections to build protection, making them less practical for short-cycle broilers. • Natural products: Attractive for their safety and residue-free profile, but historically inconsistent in performance when not scientifically validated. The industry’s reliance on these approaches is no longer sufficient. A new generation of solutions is needed—both as natural alternatives to conventional drugs and as complementary tools that fit into existing management programs (Figure 3). Eimeria species E. acervulina Pathogenicity1 Site of infection Gizzard Duodenum Jejunum Ceca Colon Lesion site2 ++ +++ +++ +++ ++ + + + + E. brunetti E. hagani E. maxima E. mivati E. mitis E. necatrix E. praecox E. tenella Figure 1. Infection sites and pathogenicity of poultry Eimeria species 1Pathogenicity level, +Mild, ++ Moderate, +++ Severe 2Lesion Site, Mark the infectable intestine site in black Unsporulated oocyst Macrogamete Gametogony Schizogony I Schizogony II + III Sporulation Microgamete Sporozoite 3 4 5 6 7 2 1 Merozoite Sporulated oocyst Sporocyst Parasitophorous vacuole membrane Figure 2. Life cycle of Eimeria spp.
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