Snail-based calcium may substitute for conventional calcium sources in laying-poultry diets, especially in regions with abundant invasive snails. The effects of snail-based calcium on egg productivity and profitability differ depending on the snail species, processing method, and inclusion level. The present study aimed to estimate the effects of snail-based calcium supplementation on hen-day production and egg weight in laying poultry. Following PRISMA guidelines, nine databases through 2025 were searched for controlled trials comparing snail-derived calcium with conventional sources in laying hens. Out of 825 records, 18 studies met the inclusion criteria after systematic screening for study design, outcome reporting, and variance data. Egg weight and hen-day production were the primary outcomes; economic outcomes were analyzed qualitatively due to limited variance in the data. Using a random-effects model, pooled results indicated that snail-shell calcium significantly reduced egg weight compared to the conventional calcium sources, with no significant effect on hen-day production. Subgroup analysis indicated that quail maintained comparable egg production when fed snail-shell calcium, whereas layer hens experienced a significant decline. Among 26 economic comparisons, 69.2% reported favorable outcomes for snail-based calcium, primarily because lower ingredient costs offset the slight reduction in egg output. Heterogeneity was high for egg weight (I² = 81.6%) and hen-day production (I² = 93.5%). Snail-based calcium can be viable when processed appropriately and used at species-appropriate inclusion levels. Overall, the meta-analytic results suggested that snail-shell calcium can be a practical, cost-effective alternative when properly processed and used at levels suited to the target poultry species.
Cordova et al. (Mon,) studied this question.