In recent times emphasis has been given on the use of non-antibiotic growth promoters in poultry rearing with a focus on phytobiotics, usually derived from herbs, spices and essential oils. Being natural they are devoid of residual and toxic effects in the body. Marigold (Tagetes erecta) flower is reported to have immunogenic and antioxidant properties (Wang et al., 2017); contribute carotenoid and flavonoid pigments (Rajput et al., 2012) possess essential oils for improved immune function and nutrient absorption leading to better growth and feed efficiency. The plant also stimulate the digestive enzymes enhancing liver function, also decreases duodenal crypt depth for protecting intestinal mucosa against pathogenic bacteria and toxic substances, thus may act as promising feed additive for poultry ration. Therefore, the present study was carried out to evaluate the effect of Marigold flower powder (MFP), a natural feed additive, at different doses on the growth performance and economy of broiler chickens.

One hundred and twenty day-old Cobb-430 Y strain broiler chicks having similar body weight from a single hatch were randomly distributed into four groups viz, C, T₁, T₂ and T₃ comprising of 30 chicks, each. Each group was further subdivided into 3 replicates of 10 chicks. The chicks were wing banded and reared under deep-litter system of management in the Instructional Poultry Farm of the CVSc, AAU, Khanapara. The control group (C) was fed with basal diet without MFP supplementation, whereas the treatment groups T₁, T₂ and T₃ were supplemented with MFP at the rate of 0.3%, 0.6% and 0.9%, respectively. The MFP was prepared by separating the petals from the flowers after cleaning thoroughly with tap water. The petals were dried in hot air oven at 50°C for 6-8 hours till become crisp and then ground to fine powder using kitchen grade mixer-grinder, hermetically sealed and stored in a cool, dark place. The chemicals present in marigold flower powder were determined through outsourcing Vimta Labs Ltd., Life Sciences Campus, Hyderabad (Table 1).



The birds were fed as per recommendation of ICAR (2013) feeding standards to meet the energy and protein requirements during pre-starter (0-14 days), starter (15-21 days) and finisher (22-42 days) phases. The ingredient and nutrient compositions of pre-starter, starter and finisher diets have been presented in (Table 2). All the birds under control and treatment groups were offered ad libitum drinking water and feed throughout the experimental period of six weeks from 17^th Jan. to 28^th Feb./2022under uniform managemental condition. The performance of broiler in respect of weekly feed intake, weekly body weight, feed conversion ratio (FCR) and economics of production were calculated as per standard methods. A Completely Randomized Design was used for statistical analysis with established technique.

The data showed that all the marigold fed groups consumed higher feed as compared to the control group (Table 3). Among the marigold fed groups the T₂ group with 0.6 % MFP consumed the highest feed followed by T₁ group with 0.3 % marigold addition, whereas T₃ group with 0.9 % dietary MFP consumed the lowest amount. This phenomenon might be because of the preference of poultry for yellow or orange colour contributed by the carotenoids from MFP. This is in accordance with the finding of Khosravinia (2007) who revealed that inherent orange colour of MFP is known to attract chicken. Also, the smell of marigold due to its carotenoids, volatile oils (Table 1) and aromatic compounds might have added for more attraction to the feed, leading to higher feed consumption in the marigold treated groups.



The mean weekly body weight value (Table 4) revealed that the body weight of control group remained lower as compared to the marigold fed groups after 1st week.  However, significant (P≤0.01) change was noticed at the end of 4th week and beyond. This development might be due to the exposure time needed for the biochemical elements present in marigold to exert appreciable physiological changes. The T₁, T₂ and T₃ groups had achieved 17.84%, 20.01% and 5.92% more live body weight than the control group, respectively. This phenomenon could be attributed to better digestion and absorption of feed nutrients due to improved gut health because of the development of increased absorptive area of the duodenum and jejunum in MFP fed groups. El-Wahab et al.  (2021) also found that supplementation of Marigold flower extract (MFE) and MFP in diet reflected in the best body weight gain in growing Japanese quail. Similarly, Rajput et al., (2012) showed that dietary supplementation with MFE in broiler diet significantly improved live body weight. In the contrary, Wang et al. (2017) found no significant difference in the growth performance due to the dietary supplementation of MFE in broiler chickens.



The overall feed conversion ratio was found to be improved, in the MFP fed broilers, justifying the better feed efficiency (Table 3). This result falls in line with the observations of  Pirman et al., (2020) who also found lower FCR due to the dietary MFE in the broilers. These results are corresponding to the works done by Agiang et al., (2011) who found that dietary inclusion of bush marigold (Aspilia africana) leaf up to 5% aqueous extract of growing and laying quails significantly improved FCR.

The production cost per live broiler was found to be (₹) 252.00, 282.60, 284.50 and 261.86 for the C, T₁, T₂ and T₃ groups, respectively (Table 5). Thus, comparing with the control group the cost of production per broiler was higher by about (₹) 30.60, 32.50 and 9.86 in T₁ ,T₂ and T₃  groups,  respectively. Accordingly, T₂ group showed the best gross profit among all. Such profitability might be attributed to the fact that the marigold fed groups had better FCR due to increased absorptive intestinal area leading to higher metabolic demand and increased protective function of the intestinal mucosa against pathogenic bacteria and toxic substances as reported by Pirman et al., (2020).

From the above study it can be concluded that Marigold flower powder has beneficial effects on growth, feed conversion ratio and gross profit per broiler chickens. Thus, the MFP at the level of 0.6% can be safely used as a natural feed additive in the diet of broiler chickens.

The present study was supported by the Faculty of Veterinary Science, AAU, khanapara.
 
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The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the University of Animal Care Committee.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.