Effects of microalgae supplementation on performance, egg quality, yolk fatty acid levels, and blood parameters in...

Microalgae have gained attention in laying hen nutrition due to their richness in n-3 polyunsaturated fatty acids (PUFA), pigments, and antioxidants. However, their efficacy in poultry diets remains inconsistent. This meta-analysis quantitatively evaluated the effects of dietary microalgae supplementation on performance, egg quality, yolk fatty acid composition, and blood biochemistry in laying hens. Thirty-six peer-reviewed articles were retrieved from Scopus, ScienceDirect, PubMed, and Google Scholar following PRISMA guidelines, and effect sizes were calculated using weighted mean differences. Microalgae supplementation did not affect feed intake (p > 0.05) but significantly improved hen-day egg production, egg weight, egg mass, yolk weight, shell traits, and Haugh units (p < 0.05). Yolk pigmentation increased in color intensity and redness (p < 0.001) but decreased in lightness (p < 0.001). Microalgae enhanced yolk total n-3 PUFA, eicosapentaenoic acid, and docosahexaenoic acid (p < 0.001), while reducing n-6 PUFA and the n-6/n-3 ratio (p < 0.05). Blood total cholesterol, aspartate aminotransferase, and alanine aminotransferase concentrations decreased (p < 0.05). In conclusion, dietary microalgae supplementation augments laying performance, enhances egg quality and yolk pigmentation, fortifies yolk with beneficial n-3 fatty acids, and promotes liver health, highlighting its potential as a functional feed additive in layer diets.