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Mexican marigold (Tagetes erecta)

Datasheet

Description
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Common names 

Mexican marigold, Aztec marigold, African marigold [English]; rose d'Inde, souci aztèque, souci africain, tagète [French]; tagete [Spanish]; cempasúchil, cempaxochitl, cempoal, zempoal, flor de muertos, clavel chino, clavelón de la India [Spanish/Mexico]; rosa de oiro, cravo de defuntos, cravo da Índia, cravo de Tunes [Portuguese]; Aufrechte Studentenblume [German]; Cempohualxochitl [Nahuatl]; المخملية القائمة [Arabic]; 万寿菊 [Chinese]; センジュギク [Japanese]; ചെണ്ടുമല്ലി [Malayalam]; جعفری گل درشت [Persian]; Бархатцы прямостоячие, Бархатцы африка́нские [Russian]; ดาวเรือง [Thai]

Products: marigold meal, tagetes, tagetes meal, zampa meal, marigold extracts, tagetes extracts, lutein

Related feed(s) 
Description 

Mexican marigold (Tagetes erecta L.) is an herbaceous plant from the sunflower family, cultivated commercially for its yellow flowers, both as an ornamental plant and as a source of feed pigments and food colouring additives. 

Morphology

Mexican marigold is an erect annual herb that grows up to a height of 180 cm. The inflorescence is a solitary terminal head, up to 12 cm in diameter, bright yellow in wild types, lemon-yellow to deep brown-red in cultivated types. There are numerous (mostly ornamental) cultivars of Mexican marigold, differing in flower colour, flowerhead size and plant height (Setshogo, 2005).

Utilisation

Tagetes erecta flowers are rich in carotenoids and are used to make feed and food pigments. Lutein is the primary xanthophyll pigment that produces the orange colour in marigold flowers, comprising up to 90% of the petals’ identified pigments, with smaller amounts of antheraxanthin, zeaxanthin, cryptoxanthin, β-carotene and about 14 other carotenoids (Bosma et al., 2003; Setshogo, 2005). Tagetes erecta is a major source of lutein, since this pigment is not produced synthetically because the process is lengthy (Breithaupt, 2007). The marigold flowers are either dried and ground to create marigold meal or extracted with a solvent (see Processes below) to produce oleoresins, saponified oleoresins and purified lutein esters (Setshogo, 2005). The quality of these products for pigmentation depends on the level of trans isomers, on the level of saponification, stability against oxidation and the chemical isomerisation used to increase the concentration of some carotenoids such as zeaxanthin. The losses in pigmentation capability due to manufacturing or storage vary between 10 and 70% (Santos-Bocanegra et al., 2004). The nature of the other components of the premixture (minerals, etc.) also influences the stability of the extract (Magnin et al., 2009). Marigold pigments show good stability to heat, light, pH changes and sulphur dioxide. They are susceptible to oxidation, which can be minimized through encapsulation or the addition of antioxidants such as ethoxyquin, ascorbic acid, tocopherols or butylated hydroxyanisole and butylated hydroxytoluene. Marigold extracts are mixed with a carrier, such as edible vegetable oils, soybean flour, maize flour or distilled water (Setshogo, 2005FDA, 2013). 

Marigold meal and marigold extracts are used in poultry feed for colouring the skin, flesh (fat) and egg yolks (Martinez et al., 2004; Muñoz-Díaz et al., 2012), and more rarely in aquacultural feeds (fish and crustacean) (Setshogo, 2005). When authorized by local regulations, marigold extracts are used as a yellow to orange colorant in a wide variety of food products including baked goods and baking mixes, beverages and beverage bases, breakfast cereals, chewing gum, dairy product analogues, egg products, fats and oils, frozen dairy desserts and mixes, gravies and sauces, soft and hard candy, infant and toddler foods, milk products, processed fruits and fruit juices, soups and soup mixes (Cantrill, 2004). Fresh and dry flowers are also used to dye wool, silk and cellulose fibres (Setshogo, 2005).

In the European Union, naturally derived lutein is classified as E161b, but marigold extract has not been assigned an E number and is traded as vegetable extract. In the United States marigold meal and its extracts are approved only as colorants in poultry feed, but not in human foods (they have not been given FDA-GRAS status) (Setshogo, 2005).

Distribution 

Tagetes erecta is indigenous to Mexico and Guatemala. It is naturalized in the rest of Central America, in the western Andes of South America, and elsewhere in the tropics. As a popular ornamental plant, it is widely cultivated all over the world, including in Africa and the Indian Ocean islands (Setshogo, 2005). As a commercial source of pigments, the major producers of marigold meal and extracts are Latin American countries (notably Peru, as from 2000 Mexico grows Mexican marigold only as an ornamental plant, India and China (Bosma et al., 2003; Breithaupt, 2007; Millán, 2014; Setshogo, 2005). Minor producers are South Africa and Zambia. Escaped plants also occur in the wild, for example along roadsides (Setshogo, 2005).

The natural habitat of Tagetes erecta is the pine-oak forest zone of Mexico in a warm, low-humidity climate. It needs full sun and it occurs from sea level up to an altitude of 2000 m in the tropics. It favours well-drained loamy and clay soils of varying pH (Setshogo, 2005).

Processes 

Marigold meal

Harvested flower heads are dried directly, or after being made into silage down to about 10% moisture content. They are ground, packed and sold as marigold or tagetes meal, with or without the addition of an antioxidant such as ethoxyquin (FDA, 2013; Setshogo, 2005). 

Marigold extracts

Marigold meal is processed with a solvent (usually hexane), resulting in a brown oleoresin that is included directly into poultry feed or further purified by saponification with 40% KOH, or an equivalent alkali solution, and then sold as saponified marigold extract. It can be further purified by washing and taken up in a suitable vegetable oil, or absorbed for example on calcium silicate, gelatin, soybean flour or starch (FDA, 2013; Setshogo, 2005). The purified carotenoids are stabilized to prevent oxidation and isomerization, and are sold in a microencapsulated form giving good dispersion when added to diets (Tyczkowski et al., 1986). Alternative methods involving enzymes that increase the extraction efficiency have been developed (Setshogo, 2005).

Environmental impact 

The roots of Mexican marigold produce secretions that contain flavonoids, amines, amides, phenols and ketones that have insecticidal and nematicidal effects (Olabiyi et al., 2007; Setshogo, 2005). In Nigeria, Mexican marigold plants significantly suppressed the gall on cowpea roots and the soil nematode population and, therefore, were suggested as a control measure against nematode pests of cowpea (Olabiyi et al., 2007). Tagetes erecta is sometimes planted in crops as an insect repellent because of its sharp peculiar smell (Setshogo, 2005). 

Nutritional aspects
Nutritional attributes 

The Mexican marigold is mainly a source of xanthophyll pigments. The dried petals may contain up to 2000 mg/kg of carotenoids (Tyczkowski et al., 1986). In a comparison of 7 commercial tagetes extracts, the xanthophyll content varied between 16 and 52 mg/kg, and was usually slightly higher than the value claimed by the producer (Magnin et al., 2009).

Ruminants 

There are no reports about the use of Mexican marigold in ruminant feeding (up to 2014). Plant extracts are to some extent effective against ticks and flukes (Elango et al., 2011). 

Pigs 

No information found (2014).

Poultry 

Poultry cannot synthesize carotenoids and must find them in the feed. Early reports showed that the inclusion of 0.25% marigold meal in the diet of chicks deficient in xanthophylls improved the pigmentation of both skin and egg yolks (Göhl, 1982). Nowadays, marigold extracts are a major source of yellow carotenoids in the formulation of commercial poultry feeds wherever a bright yellow colour in egg yolks, skin, and fatty tissues is associated with good health and premium quality by the consumer. In particular, marigold extracts are the most widely used source of lutein in poultry feed and there is an ample choice of commercial products (Muñoz-Díaz et al., 2012; Hadden et al., 1999). Usually, lutein is not applied as a sole xanthophyll to poultry feed since the egg yolk may show a greenish hue, resulting in a grey colour in processed food such as noodles. To avoid this, orange red xanthophylls are added after feeding yellow xanthophylls during the initial phase (Breithaupt, 2007). Since the 2000s, synthetic pigments such as ethyl ester of beta-apo-8-carotenoic acid (apo-ester) and canthaxanthin have been competing with tagetes for pigmenting poultry skin (Castaing et al., 2007Hamelin et al., 2013), and yolk (Santos-Bocanegra et al., 2004Sirri et al., 2007). These synthetic pigments tend to be cheaper and more efficient in attaining the same degree of pigmentation. However, because of the growing consumer demand for natural and organic products, pigments from Tagetes erecta and other plants are still valuable (Breithaupt, 2007; Santos-Bocanegra et al., 2004).

Rabbits 

No information found (2014).

Fish 

Salmonids

In aquaculture, xanthophylls are used for pigmenting the flesh of farmed salmonids as consumers expect the same colour in fish from aquaculture as found in wild fish. Additionally, xanthophylls offer strong antioxidant and provitamin A activity. Typically, the xanthophyll used in fish farming is astaxanthin, either synthetic or from natural sources, rather than lutein from Tagetes erecta (Breithaupt, 2007). Mexican marigold meal made of flowers dried in the shade and ground has been suggested as an alternative source of carotenoids for salmonids, and was also found to provide adequate pigmentation in fillets of rainbow trout (Oncorhynchus mykiss) when supplied at 1.6% of the diet. However, it was found less efficient for pigmenting than synthetic astaxanthin, and higher inclusion rates equal to or higher than 2.4% depressed growth (Buyukcapar et al., 2007).

Crustaceans 

Like fish farming, shrimp and prawn farming tends to use astaxanthin for pigmenting purposes rather than lutein and natural xanthophylls from Tagetes erecta (Breithaupt, 2007). However, studies in Mexico have found that tagetes pigments can be useful in shrimp farming (Tapia-Salazar et al., 2008).

Pacific white shrimp (Litopenaeus vannamei)

A literature review (Tapia-Salazar et al., 2008) found that the concentration of pigments found in Litopenaeus vannamei shrimps fed diets supplemented with marigold flower pigments were within the ranges reported for shrimp fed other sources of pigments. However, deposition efficiency is affected by the characteristics of the extract used, the predominant pigment, culture conditions, species, etc. Several studies have reported a benefit (under laboratory conditions or culture) on the growth and survival of shrimp fed diets supplemented with pigments from marigold flower. Improved growth and/or survival were observed in shrimp fed a saponified marigold flower extract rich in lutein (Vernon-Carter et al., 1996Arredondo-Figueroa et al., 1999). Tagetes erecta extracts added to the diet increased survival in shrimp at the larval stages, as juveniles and pre-adults, under commercial farming conditions (Martínez-Córdova et al., 2002). In juvenile Litopenaeus vannamei shrimps, diets supplemented with 75 or 150 mg/kg xanthophylls (75% zeaxanthin, 15% lutein), industrially extracted from marigold flowers, increased the astaxanthin and total carotenoid concentrations compared to shrimp fed a control diet. The results paralleled or exceeded those obtained with a diet containing 75 mg/kg supplementary synthetic astaxanthin. In general, survival was improved in shrimps fed the supplemented diets compared to those fed the control diet, with no differences in growth (Aguirre-Hinojosa et al., 2012).

Nutritional tables
Tables of chemical composition and nutritional value 
References
References 
Datasheet citation 

Tran G., Hassoun P., Lebas F., 2016. Mexican marigold (Tagetes erecta). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/90 Last updated on April 11, 2016, 10:45

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)