نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction: Carotenoids, particularly lutein and β-carotene, are natural pigments with strong antioxidant properties, widely recognized for their role in improving yolk pigmentation and mitigating oxidative stress in poultry. The growing consumer demand for natural feed additives has prompted the exploration of plant-based sources rich in carotenoids. Alfalfa (Medicago sativa L.), a commonly cultivated forage crop, is a particularly promising source due to its high xanthophyll content, including lutein and zeaxanthin, which contribute to both pigmentation and antioxidant defense. While synthetic carotenoid products, such as Lucantin®, are widely utilized in commercial poultry production for yolk pigmentation, there is increasing interest in natural alternatives that can provide comparable efficacy while potentially enhancing consumer acceptance and sustainability. The present study was designed to evaluate the effects of different inclusion levels of alfalfa carotenoid extract in comparison with commercial Lucantin® on egg quality parameters and oxidative stress indicators in laying hens.
Materials and Methods: A total of 128 laying hens were randomly assigned to four dietary treatments using a completely randomized design, with four replicates of eight birds per replicate. The experimental treatments were as follows: C) control diet based on corn-soybean, A20) control diet supplemented with 20 g/ton alfalfa extract, A30) control diet supplemented with 30 g/ton alfalfa extract, and L35) control diet supplemented with 35 g/ton Lucantin®. Carotenoids were extracted from fresh alfalfa through a sequential solvent extraction method using ethanol, ethyl acetate, and hexane at three different temperatures (25°C, 40°C, and 60°C). The extract was subsequently filtered, subjected to rotary evaporation, and saponified using 40% potassium hydroxide to remove lipids. Total carotenoid content was quantified using UV–Vis spectrophotometry according to standard lutein protocols. Egg quality traits, including shell thickness, specific gravity, yolk color (assessed using DSM YolkFan™), yolk diameter, yolk height, yolk index (ratio of yolk height to diameter), and Haugh unit, were measured at weeks 2, 4, 6, and 8. Plasma samples collected at week 8 were analyzed for oxidative stress markers, including malondialdehyde (MDA) as a lipid peroxidation indicator, as well as the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and total antioxidant capacity (TAC). Statistical analyses were performed using the General Linear Model (GLM) procedure of SAS 9.4, and differences among treatment means were evaluated by Duncan’s multiple range test.
Results and Discussion: Dietary supplementation with both alfalfa carotenoid extract and Lucantin® significantly improved yolk pigmentation compared to the control group (P<0.0001), with the Lucantin®-supplemented group exhibiting the highest color index among all treatments. Malondialdehyde (MDA) levels, representing the extent of lipid peroxidation and oxidative damage, were significantly lower in A20 and A30 compared to the control (P=0.0233), indicating enhanced systemic antioxidant status. Although no statistically significant differences were observed in the activities of antioxidant enzymes (SOD, GPx, and CAT) among the treatment groups (P>0.1), upward trends were evident in the carotenoid-supplemented groups, suggesting potential improvements in enzymatic antioxidant defense. The yolk index, an important indicator of internal yolk quality reflecting the ratio of yolk height to diameter, did not differ significantly among treatments during the first two weeks of supplementation (P>0.2). However, by week six, both A30 and L35 treatments exhibited significantly higher yolk index values compared to the control and A20 groups (P=0.016), with A30 achieving the highest yolk index overall. These findings indicate that both natural alfalfa-derived carotenoids and synthetic Lucantin® can improve yolk structural integrity, likely due to the antioxidant properties of lutein and zeaxanthin, which stabilize yolk microstructure and reduce lipid oxidation. Shell thickness remained unaffected across all treatments during the experimental period (P>0.3), and specific gravity, an indicator of internal egg quality and water-to-dry matter ratio, also showed no significant differences among dietary groups (P>0.25). Similarly, yolk diameter was not significantly altered by dietary supplementation (P>0.05), indicating that carotenoid addition primarily influenced yolk pigmentation and consistency rather than gross yolk size.
Conclusion: The current study demonstrates that dietary supplementation with alfalfa-derived carotenoids at a level of 30 g/ton effectively enhances egg yolk pigmentation and supports systemic antioxidant defense in laying hens. These effects were comparable to, and in some parameters even superior to, those observed with synthetic Lucantin®. The results highlight the potential of alfalfa as a sustainable, natural alternative to synthetic carotenoids in poultry diets, providing both functional benefits in oxidative stress mitigation and improvements in egg quality traits. Incorporating alfalfa carotenoid extract into layer diets represents a promising strategy for producing high-quality eggs with enhanced consumer acceptance, supporting both health-promoting and economically viable poultry production practices.
کلیدواژهها English
Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)
