The Effect of Dietary Black Cumin Seeds ( Nigella Sativa L . ) on the Performance of Broilers

Three hundred and sixty sexed 3-day-old broiler chicks were divided randomly into six treatment groups (control, antibiotic and black cumin at four levels) of 60 birds each. Black cumin seeds at 0.5%, 1%, 2% or 3% and avilamycin at 10 mg/kgt were added to the basal diet and their effects determined on feed intake, daily live weight gain, feed conversion ratio and carcass characteristics. There were no significant differences in daily feed intake at 21 and 42 days (p>0.05). Average daily gain was significantly different between the treatments. The birds fed the diet containing 1% black cumin seeds and antibiotic were the highest average daily gain, followed by those the other treatment diets and negative control (p<0.05). From 1 to 42 days of age, feed conversion ratios were improved significantly by supplementation with 1% black cumin seeds and with antibiotic (p<0.05) by approximately 5% compared to the control group. Similarly, the highest cold carcass, thigh, breast, wing, neck and liver weights were observed in the 1% black cumin and antibiotic groups (p<0.05). Accordingly, 1% supplementation of black cumin seeds to diets could be considered as an alternative natural growth promoter for poultry instead of antibiotics. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 3 : 425-430)


INTRODUCTION
Antibiotics were the principal growth promoting substances for poultry.However, the use of antibiotics as feed additives is risky due to cross-resistance amongstt pathogens and residues in tissues (Schwarz et al., 2001).Therefore, the use of most antibiotic growth promoters has been banned in many countries in the world.Consequently, the use of antibiotics in poultry diets was reduced and scientists have searched for alternative natural growth promoters and aromatic plants and essential oils extracted from these plants are becoming more important due to their antimicrobial effects (Elgayyar et al., 2001;Singh et al., 2002;Valero and Salmeron, 2003;Wenk, 2003) and their stimulating effect on animal digestive systems (Jamroz and Kamel, 2002;Ramakrishna et al., 2003;Jang et al., 2004).
Black cumin has been a great focus of research for centuries and has several traditional uses and consequently has been extensively studied for its active constituents (Menounos et al., 1986;Atta-ur-Rahman et al., 1992;Al-Gaby, 1998;Ghosheh et al., 1999).To our knowledge, the effect of dietary black cumin seeds on performance in broilers has not been investigated.The current study was conducted to determine usefulness of black cumin seeds in animal nutrition as a natural growth promoting substance to replace antibiotics.For this purpose, the effects of different inclusion levels of black cumin seeds were also assessed.

MATERIAL AND METHODS
Three hundred and sixty 3-day-old broiler chicks (Ross-308) were used in this study.The chicks were divided into six groups, each of 60 birds, and randomly assigned to the six treatment diets.Each treatment group was further subdivided into six replicates of 10 birds each.The experiment was carried out over 42 days.The presence and levels of black cumin seeds and antibiotic in diets were the main tested factors.The birds in the control group were fed the standard diets (18.8-21.6%CP and 13.34-13.41MJ ME/kg).Four different levels of black cumin seeds (Kırkambar Co., Elazığ, Turkey) or an antibiotic (Avilamycin, Kartal Kimya, Turkey) were added to the standard diets.For the black cumin seed treatments, 0.5% (0.5 black cumin group), 1% (1 black cumin group), 2% (2 black cumin group) and 3% (3 black cumin group) black cumin seeds were added to the standard diets.In the antibiotic treatment, the feed contained 0.1% (10 mg/kg) antibiotic.Black cumin seeds and antibiotic were mixed carefully with the standard diet.
The six diets were isocaloric and isonitrogenous.The diets and water were provided ad libitum.The ingredient and chemical composition of the diets are presented in Table 1.
A photoperiod was maintained for 23 h/d until the 4th week and for 14 h/d in weeks 4-6.The body weights of the birds were measured individually and feed intakes per pen were recorded.Feed conversion ratio was calculated at the end of the 21st and 42nd day experimental periods.Mortality was recorded daily and used to adjust the total number of birds to determine the total feed intake per bird.At 42 days, 20 birds were selected from each treatment group, weighed and slaughtered to determine carcass yields.
Chemical composition of feed ingredients (dry matter, crude protein, ash and ether extract) as dried samples were analyzed using AOAC (1990) procedures; crude fiber was determined by the methods of Crampton and Maynard (1983).

RESULTS AND DISCUSSION
The effect of dietary black cumin seeds and antibiotic on the daily feed intake and feed conversion ratio are presented in Table 2. Daily feed intake did not differ between treatments (p>0.05).Similar feed intake may be due to the birds being kept in a clean environment and fed well-balanced diets.Similarly, Denli et al. (2004) reported that supplementation with black cumin seed extract did not significantly affect feed intake of quail.From days 1 to 42, feed conversion ratios were significantly improved by supplementation with 1% black cumin, and antibiotic (p<0.05).The supplementation of 1% black cumin seeds and antibiotic in the diet improved feed conversion ratio by approximately 5% compared to the control group and by approximately 6.5% compared to the other black cumin groups.There were no differences between 0.5%, 2%, 3% black cumin groups and groups (p>0.05).
The effects of black cumin seeds and antibiotic addition on average daily gain, carcass yield and mortality are presented in Table 3.There was a significant effect (p<0.05) of 1% black cumin seeds and also of antibiotic additive on average daily gain and carcass yield.At 42 days of age, average daily gains differed (p<0.05) between treatments.The highest average daily gains were observed in antibiotic and 1% black cumin groups.The birds consuming the diets containing antibiotic and 1% black cumin improved average daily gain by 7.2% and 6.6% respectively compared to the control group.There were no differences between average daily gains of birds receiving the diets containing 0.5%, 2%, 3% black cumin and the control group (p>0.05).The average daily gain of birds fed the diets containing 0.5%, 2% and 3% black cumin seeds were lower than those of the birds on the diet containing 1% black cumin seed (p<0.05).Carcass yields differed (p<0.05) between the treatments at day 42.The birds consuming the diets containing antibiotic and 1% black cumin had a higher carcass yield than the other treatment groups (p>0.05).Significant differences were also found between 1% black cumin group and 0.5%, 2% and 3% black cumin groups.Mortality was not significantly different between treatments.The effects of black cumin seeds and antibiotic on carcass characteristics are presented in Table 4.The highest cold carcass weight were determined in antibiotic and 1% black cumin groups (p<0.05).The supplementation of the diets with 1% black cumin seed and antibiotic improved cold carcass weight approximately 8% compared to the control group.Similarly, the highest liver, abdominal fat, thigh, breast, wing and neck weights were in antibiotic and 1 % black cumin groups (p<0.05).There were no differences in heart weights between groups (p>0.05).
In summary, supplementation of the diets with 1% black cumin seed and antibiotic significantly improved average daily gain, feed conversion ratio and carcass yield.Antibiotics have been used as growth promoters in poultry for a long time and many studies have reported that  antibiotics increased live weight gain, feed conversion ratio and carcass yield (Elwinger et al., 1998;Engberg et al., 2000;Owens et al., 2004).The positive effect of supplementation with 1% black cumin seed on performance may be due to its antimicrobial effects on the pathogenic bacteria, fungi and parasites in the digestive system (Gilani et al., 2004).Different investigations have reported that black cumin had antimicrobial activity against Streptococcus mutans (Namba et al., 1985); Micrococcus pyogenes var.aureus (Kapoor, 1990); Shigella dysenteriae, Shigella sonnei, Vibrio cholerae and Escherichia coli (Ferdous et al., 1992); Staphylococcus aureus, Pseudomonas aeruginosa (Sokmen et al., 1999); Bacillus pumilus, Bacillus suptilus, Staphylococcus lutea (El-Kamali et al., 1998) and Shigella flrxneri (Chowdhury et al., 1998).
Black cumin also showed anthelmintic activity (Agarwal et al., 1979a).Additionally, the essential oil in black cumin showed antifungal activity against Aspergillus species and Curvularia lunata (Agarwal et al., 1979b) as well as against pathogenic yeast Candida albicans (Hanafy and Hatem, 1991).It is clear that controlling the gut micro flora could positively influence broiler performance.Furthermore,, the black cumin seed oil and its main active constituent thymoquinone (approximately 60%) and other components (carvone, anethole, carvacrol and 4-terpineol) have high antioxidant activity (Badary et al., 2000;Kruk et al., 2000).Also, black cumin oil (Mahmoud et al., 2002) and thymoquinone (Mansour et al., 2002) have hepatoprotective effects.Additionally, black cumin seeds have been traditionally used in a wide range of gastrointestinal disorders (El-Abhar et al., 2003).The seeds also contain lipase (Duke, 1992).Improved performance of the 1% black cumin group may be due to the combined effect of all these active ingredients acting in a positive manner.In agreement with these results, Hernandez et al. (2004) reported that the supplementation of essential oils improved apparent wholetract and ileal digestibility of the nutrients.Similarly, Ramakrishna et al. (2003) reported that the effects of pancreatic lipase and amylase were increased with the supplementation of essential oil.Also, Jang et al. (2004) reported that the supplementation of essential oil increased trypsine and pancreatic amylase activity.Similar positive effects reported by Jamroz and Kamel (2002).They observed that the supplementation with essential oil increased digestion of protein, cellulose and fat.The positive effect of dietary black cumin seeds on gain and feed conversion ratio could relate to increased efficiency of feed utilization and/or altered carcass composition.
Similarly, recent studies reported that essential oils blocked effect of pathogens in the digestive system (Alçiçek et al., 2003), and improved feed intake, feed conversion ratio and carcass yield (Tucker, 2002;Alçiçek et al., 2003;Giennenas et al., 2003).The reason for the lower performance of 2% and 3% black cumin groups compared with the 1% black cumin group may be due to negative effects of components such as alkaloids, saponin, volatile oils and other anti nutritional factors contained in black cumin.Similarly, El-Shabrawy and Nada (1996) reported that toxic symptoms were observed after intra peritoneal administration of 2.5% black cumin.The toxic effects of black cumin seeds were emphasized by Zaoui et al. (2002).
Unfortunately, reports on the value of black cumin seeds in poultry are limited.This study showed that the supplementation of 1% black cumin seeds in broiler diets significantly improved body weight, feed conversion ratio and carcass yield of broilers after a growing period of 6 weeks.Howevert, the supplementation of black cumin in excess of 1% had no additional beneficial effect on these production traits.In conclusion, these results showed that black cumin seeds (1% levels) could be used a natural growth promoter substance to replace antibiotics for broiler diets.

REFERENCES
AOAC. 1990.Official  Methods of Analysis.15 th end.Association of Official Analytical Chemists.Arlington, Virginia.Abuharfeil, N. M., S. Maher and S. V. Kleist.2001.Augmentation of natural killer cell activity in vivo against tumor cells by some wild plants from Jordan.Phytoth.Res.15:109-113.Agarwal, R., M. D. Kharya and R. Shrivastava.1979a.Antimicrobial and anthelmintic activities of the essential oil of

Table 1 .
Ingredient and chemical composition of the experimental starter and finisher diets ME: Metabolisable energy.Diet 1: Negative control: without antibiotic and black cumin seed.

Table 2 .
The effect of dietary black cumin seed and antibiotic on the average daily feed intake and the feed conversion ratio of broilers up to the age of 42 days

Table 3 .
The effect of dietary black cumin seed and antibiotic on daily live weight gain, carcass yield and mortality of broilers up to the NS: Non significant, * p<0.05, a, b Mean values with different superscripts within a row differ significantly.

Table 4 .
The effect of dietary black cumin seed and antibiotic on carcass characteristic of broilers up to the age of 42 days (n: 20) : Non significant, * p<0.05, a, b, c Mean values with different superscripts within a row differ significantly. NS