Black pepper (Piper nigrum)

Black pepper is derived from a flowering vine in the family Piperaceae, genus Piper and species Piper nigrum. Black pepper is extracted from the core of the pepper plant. This is used as a food spice which improves digestibility (Moorthy et al., Reference MOORTHY, RAVIKUMAR, VISWANATHAN and EDWIN2009) and contains a bioactive molecule, piperine, which has major pharmacological impacts on the nervous and neuromuscular systems and may aid in digestion (Ferreira et al., Reference FERREIRA, NIKOLOV, DORAUSWAMY, MEIRELES and PETENATE1999; Great, Reference GREAT2003).

Compounds of pepper consist of cupsaicin, cupsisin and cupsantine, some of which alleviate rheumatic aches (Mansoub, Reference MANSOUB2011). Piperine (1- piperolypiperidine) is a major alkaloid component of black pepper (Piper nigrum L.) and long pepper (Piper longum L.) and is responsible for its pungent and biting taste (Dogra et al., Reference DOGRA, KHANNA and SHANKER2004). The outer fruit layer contains important odour-contributing terpenes including pinene, sabinene and limonene, which impart taste enhancement and flavour (Galib et al., Reference GALIB, MAMDOOH and SABA2011).

Pepper has been used as a seasoning in cookery and in alternative medicine for the treatment of illnesses, including bronchitis and asthma (Singh and Kava, Reference SINGH and KAVA1992). Among its chemical-biological activities, piperine exhibits antimicrobial (Reddy et al., Reference REDDY, SRINIVAS, PRAVEEN, KISHORE, RAJU, MURTHY and RAO2004), anti-inflammatory (Pradeep and Kuttan, Reference PRADEEP and KUTTAN2004) and antioxidant (Mittal and Gupta, Reference MITTAL and GUPTA2000) properties. It has been shown to increase the bioavailability of certain drugs (Karan et al., Reference KARAN, BHARGAVA and GARG1999) and acts as a chemo-preventive factor against pro-carcinogens activated by cytochrome p-450 (Reen et al., Reference REEN, WIEBEL and SINGH1997). According to Kohlert et al. (Reference KOHLERT, VAN RENSEN, MARZ, SCHINDLER, GRAEFE and VEIT2000), the active principles of phytogenic additives are absorbed in the intestine by enterocytes and are quickly metabolised by the body. Piperine induces alterations in membrane dynamics and permeation characteristics, as well as the synthesis of proteins associated with cytoskeletal function, resulting in an increase in the small intestine absorptive surface (Khajuria et al., Reference KHAJURIA, THUSU and ZUTSHI2002). The administration of piperine by oral gavage (170 mg/kg of body weight) or intra-peritoneally (85mg/kg of body weight) to male albino rats was efficiently absorbed (about 97%) and its passage through the intestine indicated that the highest concentration in the stomach and small intestine occurred at approximately 6 hours after administration. Only traces (less than 0.15%) were detected in the serum, kidney, and spleen from 30 minutes to 24 hours (Bhat and Chandrasekhara, Reference BHAT and CHANDRASEKHARA1986). The rapid metabolism and the short life of piperines indicated a low risk of accumulation in the tissue. Cardoso et al. (Reference CARDOSO, LIMA, FREIRE, DORNELES and DANELLI2012), found that orally administered piperine in broiler chickens did not interfere with weight gain or liver relative weight. However, liver histopathological changes were observed in a dose-dependent manner that indicated 1.12 mg/kg of piperine with oral administration was non-toxic for broiler chickens, as previously reported for rats and mice (Dogra et al., Reference DOGRA, KHANNA and SHANKER2004; Gagini et al., Reference GAGINI, SILVA, CASTRO, SOARES, LIMA, BRITO, MAZUR, DIREITO and DANELLI2010). In addition to being a natural compound that does not produce detected residue in the animal or derived products, piperine is easily isolated in large amounts and has shown useful biological effects in studies in mammals.

Cinnamon (Cinnamomum verum)

Cinnamon is one of the oldest known herbal medicines, mentioned in Chinese texts as long as 4,000 years ago. Cinnamon is native to South America but today is cultivated in many tropical countries including India, China, Madagascar, Brazil, Mexico and the Caribbean. The essential oil of Cinnamomum bark is rich in trans-cinnamaldehyde and other biologically active substances such as cinnamyl acetate, cinnamyl alcohol, eugenol and carvacrol (Qin et al., Reference QIN, NAGASAKI, REN, BAJOTTO, OSHIDA and SATO2003) with antimicrobial effects against animal and plant pathogens, food poisoning and spoilage bacteria and fungi. Eugenol and cinnamaldehyde are two important terpenoids found in cinnamon. More than 300 volatiles have been found in essential oils from cinnamon. The essential oil derived from cinnamon leaves is rich in eugenol, which is found in camphor roots. The buds show a high amount of the sesquiterpenes α-bergamotene and α-copaene (Jayaprakasha et al., Reference JAYAPRAKASHA, RAO and SAKARIAH2002). It has been established that the oils and extracts from cinnamon possess distinct antioxidant activities, attributed to their phenolic and polyphenolic substances (Jayaprakasha et al., Reference JAYAPRAKASHA, KAMEYAMA, ONO, YOSHIDA and ROA2006). The main properties of cinnamon are that it acts as an astringent, has antiseptic, antifungal, antiviral and blood purifying properties and aids in digestion.

Cinnamon is more often used as a non-essential addition to other remedies than as a remedy by itself. Although the medicinal effects of cinnamon oil are considered to be powerful, principally it is used as an aromatic to cover the unpleasant taste of other drugs. Cinnamaldehyde and cinnamon oil vapour act as potent antifungal agents. The diterpenes found in cinnamon oil have shown anti-allergenic activity. The numerous claims for cinnamon as a medicinal herb are countered by lack of scientific research. However, animal trials have been conducted with various extracts of cinnamon, whereby Cinnamomum oil has been tested for its effect on intestinal cell viability (Fabian et al., Reference FABIAN, SABOL, DOMARACKA and BUJNAKOVA2006). In addition, the antioxidant activities of volatile extracts isolated from cinnamon have been evaluated in various in vitro assays (Lee and Shibamoto, Reference LEE and SHIBAMOTO2002). When glutathione (GSH) and lipid-conjugated dienes were studied in rats fed a high-fat diet along with cinnamon, it was reported that cinnamon stimulated antioxidant enzymes (Dhuley, Reference DHULEY1999). Such antioxidant activity may be beneficial against free radical damage to cell membranes (Dragland et al., Reference DRAGLAND, SENOO, WAKE, HOLTE and BLOMHOFF2003) and may be beneficial in alleviating the complications of many illnesses related to oxidative stress in humans and animals (Ranjbar et al., Reference RANJBAR, GHASMEINEZHAD, ZAMANI, MALEKIRAD, BAIATY, MOHAMMADIARD and ABDOLLAHI2006). Cinnamon extracts are used regularly as food antioxidants and to improve food palatability (Mancini-Filho et al., Reference MANCINI-FILHO, VAN-KOIIJ, MANCINI, COZZOLINO and TORRES1998).

Turmeric (Curcuma longa)

Turmeric (Curcuma longa) is a rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae (Chan et al., Reference CHAN, LIM, WONG, TAN, LIANTO and YONG2009) with antimicrobial and anti-oxidant properties. It is native to tropical South Asia and requires temperatures of between 20°C and 30°C and a considerable amount of annual rainfall to thrive. Its rhizome is the part related to medicinal importance and is usually boiled, cleaned, dried and powdered before use (Materia, Reference MATERIA1826). In medieval Europe, turmeric was known as Indian saffron, since it was widely used as an alternative to the far more expensive saffron pistils. Dried turmeric contains 6.3% protein, 5.1% fat, 3.5% minerals, 69.4% carbohydrates and 13.1% moisture (Chattopadhyay et al., Reference CHATTOPADHYAY, BISWAS, BANDYOPADHYAY and BANERJEE2004). Turmeric contains up to 5% essential oils and up to 5% curcumin, a bioactive polyphenol, which is also known as C.I. 75300, or Natural Yellow 3 colour agent, and has the systematic chemical name (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione. The active ingredients of turmeric are tetrahydro curcuminoid, curcumin, dimethoxy curcumin and bis-methoxy curcumin (Al- Sultan, 2003).

Research had indicated that turmeric and its active compounds possess unique antioxidants, anti-mutagenic, anti-tumorigenic, anti-carcinogenic, anti-inflammatory, anti-arthritic, anti-microbial and hypo-cholesterolemic properties (Miquel et al., Reference MIQUEL, BERND, SEMPERE, DIAZ-ALPERI and RAMIREZ2002; Gowda et al., Reference GOWDA, LEDOUX, GOERGE, BERMUDEZ and CHEN2009). In addition, the therapeutic properties of turmeric include anti-oxidant, anti-diabetic, anti-bacterial, anti-fungal, anti-protozoal, anti-viral and hypo-cholesteremic activities (Abbas et al., Reference ABBAS, IQBAL, KHAN, ZAFAR and ZIA2010; Ahmadi, Reference AHMADI2010). Turmeric is currently being investigated for possible benefits in Alzheimer's disease, cancer, arthritis and other human disorders (Gregory et al., Reference GREGORY, SPERRY and WILSON2008; Henrotin et al., Reference HENROTIN, CLUTTERBUCK and ALLAWAY2010). As an example of various laboratory research, turmeric ameliorated the severity of pancreatitis, associated with lung injury in mice (Seo et al., Reference SEO, BAE, KIM, YUN, KIM, YUN, PARK, SONG and PARK2011). Turmeric contains active compounds that beneficially stimulate bile secretion and bile flow which can support the health of the liver (Dono, Reference DONO2013). The curcuminoids (yellow pigments) present in turmeric powder have protective effects against aflatoxin B₁ (Gowda et al., Reference GOWDA, LEDOUX, ROTTINGHAUS, BERMUDEZ and CHEN2008). Turmeric traditionally has been used for conditions such as biliary disorders, anorexia, coughs, diabetic wounds, hepatic disorders, rheumatism and sinusitis. Kitikar and Basu (Reference KITIKAR and BASU1996) reported that its rhizome can be used as a calming agent, a diuretic, a hepatoprotectant and in the treatment of urinary tract and skin diseases such as scabies, leech bites and bruises.

Effect of medicinal plants on poultry performance

Tollba et al. (Reference TOLLBA, AZOUZ and ABD-SAMAD2007) showed significantly improved body weight of broilers at two, four and six weeks of age fed varying levels of dried black pepper, and, although Galib et al. (Reference GALIB, MAMDOOH and SABA2011) observed no difference in feed intake in broilers fed black pepper, Al-Harthi (Reference AL-HARTHI2006) observed that broiler chicks fed diets supplemented with hot pepper showed improvements in feed conversion ratio. Cardoso et al. (Reference CARDOSO, LIMA, FREIRE, DORNELES and DANELLI2012) reported that in the finisher period from 36 to 42 days of age, the broilers receiving a dietary supplement with 60 mg/kg of piperine showed better weight gain and feed conversion rate (P<0.05). Conversely, Hernandez et al. (Reference HERNANDEZ, MADRID, GARCIA, ORENGO and MEGIAS2004) showed that the incorporation of 200 ppm of oregano, cinnamon and essential pepper oils in broilers diets had no effect on their performance at 21 or 42 days of age. Lee et al. (Reference LEE, EVERTS, KAPPERT, FREHNER, LOSA and BEYNEN2003) reported that weight gain, feed intake and feed conversation ratio were not affected by 100 ppm dietary thymol or cinnamaldehyde, although Mehdipour et al. (Reference MEHDIPOUR, AFSHARMANESH and SAMI2013) showed that feeding 200 mg/kg cinnamon oil and virginiamycin improved feed conversion ratio compared to the control group at d21-35 and the Japanese quail at d0-35. These trials show not only a lack of consistency in results, but also that , due to combinations of treatments, comparing trial outcomes can be difficult.

There are some trials that have examined the influence of individual plant materials - for example turmeric. Mehala and Moorthy (Reference MEHALA and MOORTHY2008) reported that diets supplemented with 0.1 or 0.2% turmeric had no detrimental effects on broiler performance. Durrani et al. (Reference DURRANI, MOHAMMAD, ASAD, SUHAIL, NAILA and DURRANI2006) showed that adding 0.5% turmeric to broiler diets resulted in lower feed intake and FCR during the starting and finishing periods, but weight gain was decreased during the finishing period. Al-Sultan (Reference AL-SULTAN2003) reported that adding 0.5% turmeric to broilers’ diet improved all performance characteristics. From these reports, the use of turmeric in terms of optimal dose and age when beneficial responses are seen can start to be elucidated.

Medicinal plants and influence on carcass traits

A few controversial reports exist regarding the safety of black pepper or piperine as food additives, but examination of the proventriculus, gizzard, liver, kidney, and small intestine have not indicated any alterations in the size or the colour of the parenchyma and the mucosa of organs or the presence of lesions, when different piperine doses were added to the feed (Srinivasan, Reference SRINIVASAN2007). Mansoub (Reference MANSOUB2011) reported that the presence of antioxidants and phenolic substances in plant materials may be the main cause of improvement in a percentage of broiler carcasses. Cardoso et al. (Reference CARDOSO, LIMA, FREIRE, DORNELES and DANELLI2012) showed that supplementation with 120 and 180 mg/kg of piperine can be toxic to liver tissue and reduced the absorptive surface of the jejunum, although Hernandez et al. (Reference HERNANDEZ, MADRID, GARCIA, ORENGO and MEGIAS2004) found no change in the weight of the liver, stomach and digestive tract of broiler chicks fed a diet supplement with cinnamon extract.

Previous studies have demonstrated that relative gizzard weight was not affected by feeding turmeric or essential cinnamon oil. A reduction in carcass fat percentage (Al-Sultan, Reference AL-SULTAN2003) at doses of 1% and 1.25% turmeric powder in broiler rations has been reported. (Samarasinghe et al., Reference SAMARASINGHE, WENK, SILVA and GUNASEKARA2003). This was confirmed when a significant decrease in abdominal fat (57%) was observed by Emadi and Kermanshahi (Reference EMADI and KERMANSHAHI2006) who fed turmeric rhizome powder (0.75%) in broiler rations. Higher dressing percentages (57%) were observed when broilers were given feed supplemented with turmeric powder (Durrani et al., Reference DURRANI, MOHAMMAD, ASAD, SUHAIL, NAILA and DURRANI2006). The inclusion of turmeric powder increased liver weight and spleen weight (Al-Sultan, Reference AL-SULTAN2003) and whole giblet weight (Durrani et al., Reference DURRANI, MOHAMMAD, ASAD, SUHAIL, NAILA and DURRANI2006). Additionally studies have shown that relative gizzard weight was not affected by turmeric or essential cinnamon oil (Hernandez et al., Reference HERNANDEZ, MADRID, GARCIA, ORENGO and MEGIAS2004; Durrani et al., Reference DURRANI, MOHAMMAD, ASAD, SUHAIL, NAILA and DURRANI2006; Sadeghi et al., Reference SADEGHI, KARIMI, PADIDAR JAHROMI, AZIZI and DANESHMAND2011).

Medicinal plants and immune response

Certain trials have focussed on the impact of pepper, cinnamon and turmeric on immunity in animals, including avian species. Dogra et al. (Reference DOGRA, KHANNA and SHANKER2004) administered piperine (1.12, 2.25 and 4.5 mg/kg) for five consecutive days to determine its role in the immunotoxicity of Swiss male mice. They noted that piperine at 2.25 and 4.5 mg/kg caused a significant reduction in total leukocyte counts, increasing the percentage of neutrophil and suppressing mitogenic responses of B-lymphocyte to lipopolysaccharides. In concentrations of 120 and 180 mg/kg, piperine increased AST, indicating that hepatocyte lesions were caused by alterations in cellular membrane permeability (Kaneko, Reference KANEKO1989). Mansoub (Reference MANSOUB2011) showed that the effects of black pepper on SRBC counts in challenged broiler chickens were significantly higher than in the control group, and heterophil to lymphocyte ratios were highest in the group fed with 2% black pepper.

An increased weight of the thymus in response to cinnamon powder was believed to occur via enhanced growth of the thymocytes. Treatment with cinnamon powder in broiler feed was found to maintain a consistent increase in serum immunoglobulin production (Wang et al., Reference WANG, FIELD and SIM2000). In addition, the essential oil Cinnamomum zeylanicum showed stimulatory effects on macrophages.

For turmeric, Emadi and Kermanshahi (Reference EMADI and KERMANSHAHI2007a) reported increases in the immunoglobulins IgA, IgM, IgG and decrease in the ratio of monocytes in broilers fed with turmeric rhizome powder. Higher antibody titres were observed in turmeric fed broilers which had been challenged with Etmic-2, an apical complex protein which plays an important role in host cell invasion of Eimeria parasites (Lee et al., Reference LEE, LILLEHOJ, JANG, KIM, IONESCU and BRAVO2010). In addition, Jagdeeswaran (Reference JAGDEESWARAN2007) observed a significantly higher antibody response in birds supplemented with turmeric and vitamin E against NDV. Higher immune response due to the dietary inclusion of turmeric was recorded by Mehala and Moorthy (Reference MEHALA and MOORTHY2008) in broiler chicks. To support these findings, Nayaka et al. (Reference NAYAKA, UMAKANTHA, WILFRED and MURTHY2012) showed that inclusion of turmeric and vitamin E in the diet significantly improved the cell mediated immune response in broilers, when added to diets either alone or in combination.

Effect of medicinal plants on blood parameters and serum biochemical constituents

Various aspects of blood chemistry can be altered by feeding chickens with medicinal plants and their extracts. Galib et al. (Reference GALIB, MAMDOOH and SABA2011) showed that chickens fed black pepper had significantly lower cholesterol, H/L ratio, red blood cells (RBC), packed cell volume (PCV) and haemoglobin (Hb) compared with a control group. The reduction of PCV, Hb and RBC may be due to the activity of black pepper on oestrogen, as this hormone decreases erythrocyte formation and PCV. Since black pepper contains high levels of fibre this may be the reason for the decline in cholesterol and triglycerides in the blood stream.

Levels of liver enzymes (ALT & ALP) were substantially reduced by supplementing broilers with turmeric powder (Emadi and Kermanshahi, Reference EMADI and KERMANSHAHI2007b). Reductions of these enzymes are important as their accumulation in the liver are related to toxicity. No changes in serum total cholesterol, HDL-c, LDL-c and triglyceride concentrations have been shown in broiler chickens when receiving diet supplements with 0.1% or 0.2% turmeric powder (Mehala and Moorthy, Reference MEHALA and MOORTHY2008). Dietary supplementation of laying hens with 0.2% turmeric powder resulted in lower serum triglyceride and total cholesterol concentrations (Kermanshahi and Riasi, Reference KERMANSHAHI and RIASI2006) and the inclusion of 0.1% or 0.5% curcumin in rat diets lowered the liver and serum cholesterol concentrations (Babu and Srinivasan, Reference BABU and SRINIVASAN1997). Moreover, dietary supplementation of curcumin decreased plasma cholesterol, free fatty acids and triglyceride concentrations in female albino rats with alcohol-induced liver toxicity (Rukkumani et al., Reference RUKKUMANI, SRIBALASUBASHINI and MENON2003). Curcumin has been reported to enhance the concentration of catalase, as well as the expression of hepatic superoxide dismutase (SOD) (Cheng et al., Reference CHENG, LIU and AI2005) and glutathione peroxidase (Yarru et al., Reference YARRU, SETTIVARI, GOWDA, ANTONIOU, LEDOUX and ROTTINGHAUS2009), the enzymes that known to have a close relationship with the antioxidant status of the body. Kamal-Eldin et al. (Reference KAMAL-ELDIN, FRANK, RAZDAN, TENGBLAD, BASU and VESSBY2000) reported reduced low plasma density lipoprotein and very low-density lipoprotein and total cholesterol concentrations in the livers of male Sprague-Dawely rats by dietary supplementation of 4 g/kg curcumin. Hence there is growing evidence of the specific effects on organs and blood of using pepper, turmeric and cinnamon supplementation in chicken diets.