The Impact of Bentonite Feed Additives on Laying Hens Performance and Egg Quality: A Meta Analysis

This study aimed to evaluate the effect of bentonite as a feed additive on the performance and egg quality of laying hens through a meta-analysis approach. The keywords “bentonite”, “clay”, “montmorillonite” and “laying hens” were used to search scientific articles in Science Direct, PubMed, Google Scholar, and Scopus. A total of 14 articles were included in the database and were analyzed for a meta-analysis using a mixed model method. Different studies were considered as random effects, while bentonite levels were considered as fixed effects. The statistical models used were P-value, root means square error and Akaike information criterion. Results showed that bentonite level quadratically (P 0.05) increased egg production and decreased feed intake. The optimum supplementation of bentonite levels for egg production and feed intake were 2.19% and 1.63%, respectively. Egg weight, eggshell strength, and percentage of eggshell weight represented a linear increase (P 0.05) with increasing bentonite levels. Yolk’s color score showed a linear decrease (P 0.05). Meanwhile, feed conversion ratio, egg mass, egg crack, eggshell thickness, and Haugh unit were not affected by dietary bentonite. It can be concluded that dietary supplementation of bentonite at the appropriate level has a positive impact on egg production, feed intake, egg weight, eggshell strength, and percentage of eggshell weight, but has no significant effect on feed conversion ratio, egg mass, egg crack, eggshell thickness, and Haugh unit. Increasing the level of bentonite can reduce yolk color. The optimum dietary bentonite level for egg production is 2.19% which is close to the EFSA recommendation.