Review articles

The influence of the phytobiotic tulsi (Ocimum sanctum) on broiler production and health

Wafaa A. Abd El-Ghany

Wafaa A. ABD EL-GHANY, Poultry Diseases Department, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt, (Corresponding author: e-mail: wafaa.soliman@cu.edu.eg)
https://doi.org/10.46419/vs.55.2.1

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Abstract

Various types of phytobiotics have been recently used in poultry production systems to avoid the development of drug resistance and tissue residues. One such phytobiotic is holy basil or tulsi (Ocimum sanctum), an aromatic plant with multiple therapeutic functions. The powder or extract of tulsi is rich in essential oils and organic acids, which have positive effects on the physiological functions. It has been extensively used in medicine to treat many health issues. Moreover, in poultry industry, dietary tulsi has been recommended for the enhancement of general health conditions with promising results. Enrichment of broilers diets with tulsi improved the growth rate, carcass characteristics, and gut health, relived stress, and modulated the immune response and some biochemical blood parameters. This review article presents in details the different influences of dietary tulsi on these parameters in broilers.

Key words: Tulsi (Ocimum sanctum); chickens; growth parameters; carcass characteristics; antimicrobial and antioxidant; immunity

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Introduction

In recent decades, antibiotic growth promoters have been used as feed additives in the poultry industry for the improvement of feed utilisation and maintenance of gut health against infections. However, the development of antibiotic resistance and the presence of tissue residues have become issues of great concern (Wierup, 2001). In 2006, the European Union prohibited the use of antibiotic growth promoters in animal production. There has since been great concern towards finding natural and effective alternatives to antibiotic growth promoters. Herbal-derived phytobiotics play a game-changing role in livestock production. Greater attention has recently been gained with the use of these phytobiotics for their potential effects as alternatives (Abd El-Ghany, 2020; Islam et al., 2023). Herbal formulations have shown promising and encouraging results in terms of improvement of feed efficiency and performance parameters, decreasing mortalities, and increasing immunity.

Among the known phytobiotics, the genus Ocimum of the family Lamiaceae (Kadian and Parle, 2012) includes nearly 30 species of small herbs that are mainly grown in the tropics and warm regions (Paton, 1992). Ocimum sanctum is known as holy basil or tulsi, the mother medicine of nature, or the queen of herbs owing to its rich composition of bioactive components (Bhatt, 2014). The name “tulsi” means “the incomparable one” in Sanskrit. It is an aromatic plant and its parts (flowers, stem, root, leaves, seeds, etc.) possess therapeutic and medicinal potential (Singh and Majumdar, 2003; Pandey and Madhuri, 2010; Singh et al., 2010). The leaves of tulsi contain bright yellow volatile oils (eugenol, eugenal, methyl chavicol, limatrol, and caryophylline), organic acids (ascorbic, labiatenic, and palmitic acid), ß-carotene, ß-sitosterol, tannins, and a number of terpenes and monoterpenes (barnyl acetate, ß-elemense, methylengenol, neral, ß-pinene, comphene, pinene etc.) (Eevuri and Putturu, 2013).

Tulsi has displayed antimicrobial (Joshi et al., 2009), antiemetic, antioxidant (Subramanian et al., 2005), antiparasitic (Gupta, 2005; Bihari et al., 2010; Sea et al., 2017), antispasmodic, antidiabetic, antitussive (Maity et al., 2004), anti-infertility, and anti-ulcerogenic properties, as well as cardioprotective, hepatoprotective, analgesic, adaptogenic (Singh et al., 2012), and diaphoretic activity (Mondal et al., 2009). Moreover, the immunomodulatory, anti-stress, anti-inflammatory, anticancer, antipyretic, anti-asthmatic, hypotensive, and hypoglycaemic effects of tulsi have been reported (Gupta et al., 2006; Baliga et al., 2013; Eevuri and Putturu, 2013).
The consumption of tulsi has shown no genotoxic or organ toxic effect (Chandrasekaran et al., 2013).

In poultry breeding, tulsi is supplemented as a dry powder in the diet (Nath et al., 2012) or an extract in drinking water (Alom et al., 2015). The different influences of tulsi on broiler production and health are illustrated in Figure 1.

Figure 1. The different influences of tulsi on broiler production and health.

Reports indicated that supplementation with tulsi in optimum doses results in an augmentation of performance and biochemical blood parameters, as well as improvement of economic traits and digestibility (Bhosale et al., 2015; Shende et al., 2019, 2020a,b, 2021; Naeem et al., 2022). From the economic perspective, the report of Islam et al. (2021) proved that the dietary addition of tulsi leaf extract for broilers may be useful for safe, economical, and efficient production, while also reducing production costs via reducing the use of antibiotics or vaccines.
In addition, Vasanthakumar et al. (2013) revealed that the feed cost per unit weight gain was higher in groups receiving the tulsi extract. Recent studies have indicated that tulsi extract containing terpenoid and polyphenol has potential to combat some viral infections, such as influenza (H9N2 virus) (Ghoke et al., 2018) and coronavirus (Mohapatra et al., 2021; Dahiya et al., 2022).

In light of the above, this article focuses on the different influences of using tulsi (Ocimum sanctum) on broiler production regarding growth parameters, carcass characteristics, gut health, oxidative stress, immunity, and the biochemical blood parameters.

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The different influences of tulsi on broiler production and health

Growth parameters

The different effects of using of tulsi on the growth parameters of broilers are presented in Table 1.

Table 1. The effect of tulsi on the growth parameters of broilers.

Better feed intake and feed conversion ratio in tulsi fed broilers have been demonstrated in several studies (Mazhar et al., 2007; Carmona-Fernandez et al., 2009; Sheoran et al., 2017; Hossain et al., 2021; Neem et al., 2022). The augmented feed intake or appetite following supplementation with tulsi might be owing to its antimicrobial activity, increased secretion of digestive enzymes, improved digestive performance, and consequently better intestinal absorbability (Yang et al., 2009). However, other reports have shown an insignificant effect of tulsi leaf powder supplementation on the feed intake of broilers (Lanjewar et al., 2009; Vasanthakumar et al., 2013; Bhosale et al., 2015). This reduction in feed intake has been reported in experiments using tulsi containing eugenol in high concentrations, which resulting in decreased palatability and gut motility (Daniel et al., 2009).

Mixing tulsi leaf extract in drinking water of Cobb broilers significantly increased body weight by 16.97% when compared to the control non-treated broilers (Hasan et al., 2016). Similarly, supplementation with tulsi leaves extract in feed and water resulting in a significant increase (16.43%) in the live body weight compared to the control non-treated group (Islam et al., 2021).
In the presence of a bacterial disease condition such as colibacillosis, feeding on tulsi leaf powder at a level of 5g/kg feed resulting in increased body weight gain (Kumara, 2012). The bioactive compounds present in tulsi such as eugenol (Prakash and Gupta, 2007), apigeninursolic acid, rosmarinic acid, carnosol, cirsimaritin, and cirsilineol may act as potent anti-inflammatory and redox/antioxidants which help to improve body weight gain (Kelm et al., 2000). In addition, the antimicrobial, anti-protozoal, and antioxidant properties of tulsi might be reasons for this body weight enhancement (Khatun et al., 2013; Hasan et al., 2016).

Carcass characteristics

Tulsi exerts have a beneficial influence on carcass yield especially at low inoculation levels (Vasanthakumar et al., 2013; Islam et al., 2023). Singh et al. (2014) demonstrated that feeding broiler chickens with 1% tulsi leaf powder induced a significant increase in the muscle weight of breast and thigh, and higher overall body weight compared to control chickens. Incorporation of tulsi is usually accompanied by enhancing the amino acid absorption and nutrient utilisation, improving protein metabolism, and thus increasing carcass yield (Mansoub, 2011).
Further, an increase in the relative weight of the heart of broilers given tulsi has been also reported (Hossain et al., 2021; Islam et al., 2023). The higher heart weight of the tulsi-treated could be more useful in terms of an increased ability to tolerate heat stress.

Nevertheless, the dressing percentage and the weight of the heart, gizzard, spleen, and pancreas were insignificantly different between chicken groups fed diets supplemented with or without tulsi leaves (Nath et al., 2012). Likewise, insignificant differences have been detected in hot carcass and liver weights, and in the dressing percentage after treatment with tulsi leaf powder (0.5%) and tulsi leaf extract (0.1%), while intestinal length was longer in treated groups than in non-treated ones (Vasanthakumar et al., 2013).
The findings of Alom et al. (2015) indicated no differences in the mean weights of the proventriculus, gizzard, intestine, liver, and pancreas of broilers supplemented with dietary tulsi. Comparable results have been also reported by Kohri et al. (2022) who detected an insignificant effect of different tulsi levels on carcass yield, and on liver, heart, and gizzard weights of chickens. Also, Prajapat et al. (2018) found insignificant differences in the relative heart weights of chickens in the control group and those fed on dietary tulsi leaves.

Gut health

The intestinal villus surface area was increased in broilers supplemented with dietary microencapsulated tulsi oil (Thuekeaw et al., 2022). Recently, a significant improvement in the small intestine villus height and surface area following the dietary addition of tulsi (3%) was detected, while these parameters were mostly not shown in the large intestine (Islam et al., 2023). The increase in the villus absorptive surface area enhances intestinal absorbability and digestibility, and accordingly improves the growth performance (Mohamed et al., 2014). On the other hand, some reports have shown that the intestinal villi height and width and crypt depth were not affected by feeding on tulsi (Chowdhury et al., 2018; Jahejo et al., 2019).

Regarding the antibacterial effect of tulsi, a significant increase in Lactobacillus spp. and decrease in Escherichia coli (E. coli) counts of the caecum were reported in tulsi-supplemented broiler chickens (Islam et al., 2023). It has been found that Lactobacillus spp. prohibits the growth of intestinal pathogenic bacteria such as E. coli, while enhances the immune response (Xiang et al., 2022). However, E. coli is a highly pathogenic bacterial species associated with a high morbidity and mortality rate of poultry (Liang et al., 2021). Eugenol is a major essential oil of tulsi that shows a potent antibacterial effect (Eevuri and Putturu, 2013). The aqueous extract of tulsi leaves has also exhibited prophylactic potential against Pheretima posthuma (Joshi et al., 2013) and Ascaris suum (Sentana, 2010). Tulsi contains flavonoid, phenolics, and tannin (Karumari et al., 2014), which interfere with energy generation in helminths by uncoupling oxidative phosphorylation and binding to free proteins of the host’s gut or glycoprotein on the cuticle of the parasite, thus leading to parasite death (Athanasiadou et al., 2001).

Oxidative stress

Tulsi has been found to combat oxidative stress in broilers by increasing the anti-oxidative enzyme levels (Reddy et al., 2009). Incorporation of tulsi leaf powder (0.5%) with selenium (0.3 ppm) in the diet of broiler chickens increased the levels of superoxide dismutase (SOD) and catalase, which in turn reduced the oxidative stress produced during the rapid growth period (Reddy et al., 2009).
Also, the dietary addition of tulsi extract (0.1%) significantly increased glutathione peroxidase activity in chicken’s serum (Vasanthakumar et al., 2013). Additionally, Bharavi et al. (2010) indicated that administration of tulsi (0.1%) in the feed of broiler chickens reversed antioxidant enzymes such as SOD and catalase, non-enzymatic antioxidants glutathione, and lipid per oxidation marker (TBARS) produced due to cadmium-induced oxidative toxicity. A comparative study on anti-stressor and anti-oxidative effects of synthetic vitamin C and polyherbal feed premix containing tulsi supplementation in broilers during the summer showed that the antioxidant enzyme glutathione reductase was significantly decreased in treated groups in comparison with the control (Sujatha et al., 2010).

Immunity

The immune modulatory effect of tulsi has been previously reported (Manjunatha, 2002; Batra and Gupta, 2004; Kumar et al., 2012). An early study of Pimprikar (1994) confirmed the immunomodulatory effect of tulsi leaves in immunocompromised infectious bursal disease infected broiler chickens. Moreover, treatment of broilers with tulsi leaf powder (0.5%) induced a better immune response to Newcastle disease virus as compared to the untreated control group (Vasanthakumar et al., 2013). Supplementing immunosuppressed broiler chickens with dry leaves of tulsi and Indian gooseberry plant at a level of 3g/kg feed for 2 weeks protected the birds from immune suppression, and this effect was positively reflected on the body weight gain (Mode et al., 2009). Tulsi is rich in biologically active compounds, including eugenol, ursolic acid, apigenin, and luteolin which have a chief role in enhancing the mediated immune response. Consequently, feeding of immunosuppressed birds on tulsi may induce an enhancement of their humoral and cell mediated immunity (Sen, 1993; Singh and Doley, 2014).

Biochemical blood parameters

Supplementing broiler feed with tulsi leaf powder resulted in a significant reduction in serum triglyceride and total cholesterol levels (Lanjewar et al., 2009; Shende et al., 2020a). Similar results were also obtained by Kohri et al. (2022) who reported a significant reduction in serum triglyceride and cholesterol levels in broiler chickens treated with 0.5% tulsi in the diet. In addition, Sujatha et al. (2010) showed that plasma cholesterol and stress hormones, particularly cortisol and thyroxine, were significantly lowered after treatment of heat-stressed broiler chickens with vitamin C and a polyherbal feed premix containing tulsi and other herbal plants. Higher values of red blood cell counts in broiler chickens (Hasan et al., 2016) and white blood cell and platelet counts in quails (Neem et al., 2022) have been obtained by feeding on tulsi, which may help in enhancing the immunity levels against infectious diseases. Tulsi powder (0.5%) significantly increased the ascorbic acid level in the serum of chickens (Vasanthakumar et al., 2013).

An opposite finding was reported by Gupta and Charan (2007) who found an insignificant effect of tulsi leaf powder on haemoglobin and packed cell volume values of broilers. Also, no differences in the levels of total protein, albumin, globulin, haemoglobin, and packed cell volume were found in a tulsi treated group and the untreated control group (Kohri et al., 2022).

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Conclusion

It is clear that supplementation of broilers with tulsi induced positive influences on bird health in terms of improved performance parameters, carcass characteristics, gut health, and immune status, as well as alleviation of stress, and modifications of important blood parameters.
However, the mechanisms by which these parameters are stimulated have not yet been fully investigated. Therefore, more studies are required in this area to elucidate the mechanisms behind this.


References [… show]

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Utjecaj fitobiotičkog svetog bosiljka (Ocimum sanctum) na proizvodnju i zdravlje tovnih pilića

Wafaa A. ABD EL-GHANY, Poultry Diseases Department, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt

Različite se vrste fitobiotika odnedavna rabe u sustavu proizvodnje peradi i da bi se izbjegao razvoj otpornosti na lijekove i njihovih ostataka u tkivu peradi. Jedan od tih fitobiotika je sveti bosiljak ili tulsi (Ocimum sanctum), aromatična biljka s višestrukim terapijskim djelovanjem. Prah ili ekstrakt svetog bosiljka bogat je esencijalnim hlapljivim uljima i organskim kiselinama koje imaju pozitivne učinke na fiziološke funkcije tjelesnih organa, stoga je raširen u uporabi u medicini za liječenje brojnih zdravstvenih problema. U peradarskoj industriji, prehrambeni sveti bosiljak preporučen je za poboljšanje općeg zdravstvenog stanja s dobrim rezultatima. Uporaba svetog bosiljka u prehrani tovnih pilića rezultirala je poboljšanjem stope rasta, kvalitetom mesa, zdravlja želudca, smanjenjem stresa, kao i moduliranjem imunološkog odgovora i nekih hemato-biokemijskih parametara. Stoga, ovaj pregledni članak detaljno predstavlja različite utjecaje prehrambenog svetog bosiljka na navedene parametre u tovnih pilića.

Ključne riječi: sveti bosiljak (Ocimum sanctum), pilići, parametri rasta, svojstva trupla, antimikrobni i antioksidativni, imunitet

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Wafaa A. ABD EL-GHANY

Wafaa A. ABD EL-GHANY, Poultry Diseases Department, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt