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Effects of Dietary Crude Glycerol Supplementation on Performance, Egg Quality, and Yolk Fatty Acids in Laying Hens: A Systematic Review and Meta-Analysis
Author(s)
Sulaimon, Rasheed Olayiwola
Sahatsanon, Katatikarn
Jayanegara, Anuraga
Date Issued
May 1, 2026
Type
Review
Abstract
This study evaluated the effects of dietary crude glycerol supplementation on laying performance, egg quality traits, and egg yolk fatty acid composition in laying hens. A systematic search of peer-reviewed literature from major scientific databases identified thirteen eligible studies. Effect sizes were calculated as mean differences using random-effects models, and subgroup and meta-regression analyses were conducted to assess the influence of inclusion level, hen age, strain, and dose–response relationships. Moderate inclusion of crude glycerol (≤4%) significantly increased egg production (MD = +0.71 percentage points; p = 0.019) and egg mass (MD = +1.08 g; p = 0.007). External egg quality traits, including shell thickness, shell breaking strength, and shell percentage, were not significantly affected, while albumen height decreased slightly (MD = −0.14 mm; p = 0.004) and Haugh unit remained unchanged. Crude glycerol supplementation also increased linoleic acid, total unsaturated fatty acids, and total polyunsaturated fatty acids (p < 0.001). Responses varied with inclusion level, hen age, and strain, and a positive dose–response relationship between crude glycerol level and yolk linoleic acid was observed in white-egg strains. Overall, moderate crude glycerol inclusion can partially replace conventional dietary energy sources with minimal adverse effects on egg quality.
Citation
Animals, 16(10), 2026