Natural feed additives are also picking up traction in contemporary poultry rearing where industry players need chemical additive substitutes that can foster further poultry well-being, production levels, and the quality of resultant products. Some of these naturals, like Tagetes erecta or African marigold extract, stand out as an emerging additive candidate. They abound with bioactive compounds, notably lutein, zeaxanthin, and flavonoids, whose presence marks this natural resource as a potential double-action additive useful for driving immune response among poultry and enhancing the color of yolk egg contents.
Marigold Extract Knowledge
Marigold extract is prepared from Tagetes erecta dried flowers by solvent extraction. The interested compounds in the extract are xanthophylls, i.e., lutein (C40H56O2) and zeaxanthin (C40H56O2), both carotenoids. They are not produced in poultry and need to be acquired through feeding.
Apart from carotenoids, marigold extract possesses a variety of phenolic compounds, flavonoids, and essential oils with antioxidant, anti-inflammatory, and immunomodulatory activity.
Effects on Egg Yolk Pigmentation
Increasing egg yolk color is the best-documented application of marigold extract as a feed ingredient for poultry. Yolk color is an important quality factor for consumers and is influenced by dietary carotenoid intake.
Mechanism of Pigmentation
Carotenoids like lutein and zeaxanthin are directly deposited into egg yolk. These xanthophylls are taken up in the small intestine of the hen and transported via the bloodstream to the ovary, where they are deposited in growing oocytes. This results in a darker, deeper yellow to orange color of the yolk.
Surai et al. (2003) indicate that marigold extract containing 1.5–3% lutein is effective enough to enhance yolk coloration without compromising egg quality. Furthermore, when mixed with other coloring substances such as paprika or red pepper extract, marigold can create even darker colors.
Scientific Evidence
- Sun et al. (2015) found that marigold flower powder supplemented in the layer feed at a rate of 15 g/kg significantly enhanced yolk color scores without impacting egg production.
- Karadas et al. (2006) verified that lutein and zeaxanthin contents in egg yolks were increased by marigold supplementation and were associated with higher yolk pigmentation values on the Roche Color Fan scale.
Immune-Enhancing Effects of Marigold Extract
In addition to coloration, marigold extract is also rich in immunomodulatory activities. Marigold's flavonoids, saponins, and carotenoids have anti-inflammatory and antioxidant activities that modulate the immune system.
Anti-Inflammatory and Antioxidant Role
Poultry immune systems are under constant assault from stressors such as heat stress, infection, and high-density rearing. Antioxidants reverse oxidative stress, which otherwise diminishes immune capacity.
Lutein and zeaxanthin were found to regulate cytokine production and increase titers of antibodies in broilers and layers (Chew & Park, 2004).
Marigold flavonoids can decrease pro-inflammatory markers such as IL-6 and TNF-α and thus aid in improved immune balance (Kim et al., 2008).
Maintaining Gut Immunity
Gut-associated lymphoid tissue (GALT) is an integral component of avian immunity. Certain studies illustrate marigold extract enhances gut immunity through the preservation of healthy intestinal morphology and microbial balance.
Zhang et al. (2020) illustrated increased height of intestinal villi and crypt depth in broilers supplemented with marigold extract, suggesting enhanced nutrient absorption and gut health.
Moreover, lutein has been reported to increase expression of tight junction proteins, thus improving gut barrier integrity (Tang et al., 2019).
Advancements in Broiler Production
Marigold extract is not limited to layers. In broilers, it can likewise increase growth performance, immunity, and carcass quality.
Growth Performance and Feed Efficiency
A number of studies have shown that marigold supplementation can greatly increase feed conversion ratio (FCR) and daily weight gain in broilers.
A 2022 study by Younis et al. indicated that dietary supplementation with marigold extract at 0.5% inclusion enhanced body weight gain and lowered FCR in broiler chickens.
The improvement is likely to be caused by enhanced nutrient utilization and infection resistance, lowering energy cost on fighting infection.
Other Health Benefits
Eye Health and Oxidative Stress
Lutein and zeaxanthin are of special significance to the eye health of birds. They concentrate in the retina and shield ocular tissues from photo-oxidative injury. In commercial broilers with high light exposure, this is an essential advantage.
Bird research, such as quail and broilers, has reported enhanced histology of the eyes and retinal pigment concentration upon lutein supplementation.
Decreased Mortality and Disease Incidence
Through stimulation of general immunity and mitigation of oxidative stress, marigold extract has the secondary effect of decreasing mortality rates and disease incidence such as coccidiosis and respiratory infections.
Dosage and Inclusion Rates
The best dose of marigold extract is a function of the desired goal:
- Inclusion rates for egg pigmentation are generally between 5 and 20 g/kg of feed.
- For antioxidant and immune function, effective doses are a little higher-10 to 30 g/kg, depending on the level of extract strength.
- Standardization of commercial marigold powders or extracts to contain a fixed level of lutein must be assured for reproducible results.
Comparison with Synthetic Pigments and Additives
Although synthetic pigments such as canthaxanthin have been extensively used in poultry feed, concern regarding their long-term safety and consumer acceptability is growing.
Marigold extract provides a natural, consumer-preferred solution with other health benefits. Additionally, it is also generally recognized as safe (GRAS) and acceptable for use in conventional and organic crop production systems.
Limitations and Considerations
Although beneficial, there are some limitations:
- Cost: Natural extracts are more costly compared to synthetic ones.
- Color variability: Effects can be variable based on extract quality and bird metabolism.
- Oxidation: Marigold extract is thermostable and photosensitive and must be properly stored and handled.
Nevertheless, with the right sourcing and formulation, these disadvantages could be mitigated.
Conclusion
Powdered marigold extract is an all-purpose natural poultry feed supplement. In addition to dyeing the egg yolk because of its rich contents of lutein and zeaxanthin, it also strengthens immune performance, intestinal health, and general performance in broilers as well as layers. With the preference of consumers going towards natural and health-promoting products, marigold extract is a convenient way for sustainable and profitable poultry rearing.
References
Chew, B. P., & Park, J. S. (2004). Carotenoid action on the immune response. Journal of Nutrition, 134(1), 257S–261S. https://doi.org/10.1093/jn/134.1.257S
Karadas, F., Grammenidis, E., Surai, P. F., & Sparks, N. H. C. (2006). Effects of carotenoids from lucerne, marigold and tomato on egg yolk pigmentation and carotenoid composition. British Poultry Science, 47(5), 561–566.
Kim, D. O., Jeong, S. W., & Lee, C. Y. (2003). Antioxidant capacity of marigold extracts. Food Chemistry, 84(1), 19–26.
Sun, J., Wang, Y., Xia, X., & Wang, K. (2015). Effect of dietary marigold extract supplementation on egg production and yolk color in laying hens. Poultry Science, 94(9), 2164–2170.
Zhang, X., Li, Q., Hu, Y., & Chen, Y. (2020). Effects of marigold extract on growth performance and intestinal morphology in broilers. Animal Nutrition, 6(3), 274–279.
Tang, T., Zhao, X., Jin, Y., & Xu, D. (2019). Lutein modulates intestinal barrier function and inflammation. Food & Function, 10(3), 1513–1520.
Younis, M. E., et al. (2022). Effects of dietary marigold extract on broiler performance. Journal of Applied Poultry Research, 31(2), 300–308.
Li, C., Gao, Y., & Zhang, X. (2014). Lutein and eye health in birds: Protection against light-induced damage. Avian Biology Research, 7(1), 23–30.
