Hemp (Cannabis sativa L.) products have gained attention in poultry nutrition for their rich content of polyunsaturated fatty acids (PUFAs), bioactive compounds, and potential functional benefits. However, findings on their impact on laying-hen performance, egg quality, and yolk fatty acid profiles have been inconsistent. This meta-analysis aimed to evaluate the effects of dietary hemp products on laying-hen performance, egg quality traits, and yolk fatty acid composition, while exploring potential sources of heterogeneity across studies. A comprehensive literature search identified 21 studies that met the inclusion criteria. A random-effects model was used to calculate standardized mean differences (SMDs) with 95% confidence intervals (CIs) for various outcomes, including production performance, egg quality, and yolk fatty acid profiles. Subgroup and meta-regression analyses assessed the influence of factors such as inclusion level, hen age, and hemp product type. The results showed that hemp supplementation had no significant effect on hen-day production, egg mass, feed conversion ratio, or feed intake. However, yolk redness (SMD = 4.40; 95% CI: 2.46, 6.33; p < 0.001) and yellowness (SMD = 4.45; 95% CI: 2.75, 6.16; p < 0.001) were significantly enhanced. Hemp feeding also increased n-3 PUFA levels in egg yolk, including C18:3n3, C20:5n3, and C22:6n3, while reducing saturated and monounsaturated fatty acids. Subgroup analysis indicated that inclusion levels > 10% and hen age ≤ 25 weeks were associated with slight reductions in hen-day production, whereas older hens (>25 weeks) showed increased egg weight. In conclusion, hemp products can enrich yolk pigmentation and n-3 PUFA content in eggs, supporting the production of functional, value-added eggs without compromising the laying-hen performance.

This study investigated the effects of dietary Cannabis sativa residues (CR) on broiler growth and meat characteristics. A total of 256 one-day-old male Ross-308 broilers were randomly assigned to four treatments: a basal diet (control) and diets containing 0.5%, 1%, and 2% CR. CR supplementation had no effect on growth performance, survival rate, or European production index but reduced average daily feed intake (p < 0.01). No significant differences were found in meat pH, color, drip loss, thawing loss, cooking loss, or shear force (p > 0.05). However, the ΔE values (0.5% CR: 3.97, 1.0% CR: 3.71, 2.0% CR: 4.95) indicated perceptible color differences compared to the control. CR significantly reduced C12:0, C20:1n9, and C22:1n9 fatty acids (p < 0.05) while increasing free amino acids, including aspartic acid, serine, proline, methionine, and phenylalanine (p < 0.05). It also increased moisture content and decreased fat content, especially at 2% CR (p < 0.05). In conclusion, CR supplementation improves the flavor and nutritional value of broiler meat and is a potential alternative to conventional feed additives.