Improvement of antioxidant status, inflammatory responses, hematological and biochemical parameters, and performance by black seed (Nigella sativa) supplementation in broiler chickens under induced physiological oxidative stress

Oxidative stress is inevitable in broiler chicken production, and it affects the physiological, behavioral, and biochemical status of growing chicken which ultimately deteriorates meat quality. The imbalance among free radicals and antioxidant enzymes within living cells or tissues leads to the oxidation of lipids, proteins, and nucleic acids and is a fundamental cause of oxidative stress. When the antioxidant mechanism within living cells weakens, the production of free radicals increases under physiological oxygen metabolism, and reactive species (i.e., reactive oxygen species and reactive nitrogen species) are needed in cells in small quantities because they function as signaling molecules during homeostasis. However, excessive production of these species leads to oxidative stress. There is a mechanism in living cells to reduce the number of oxidative species through physiological scavenging. Numerous reactive oxygen species such assuperoxide and hydrogen peroxide are produced during oxygen metabolism. In addition, some reports showed that after the occurrence of oxidative stress, there are severe inflammatory reactions in the cells involved, which can lead to greater tissue damage and activate tissue apoptosis. Oxidative stress plays an essential role in the emergence of a number of chronic disorders such as diabetes and cancer by inducing inflammation. To protect against free radicals, living organisms have a combined antioxidant defense system including enzymatic system (such as glutathione peroxidase, superoxide dismutase, and catalase enzymes in the cytosol and cell membrane structure) and a non-enzymatic system (such as glutathione, polyphenol, carotenoids, special dipeptides, proteins containing thiol group, polyamines, ubiquinol, flavonoids, bilirubin, uric acid, vitamin E with selenium, and vitamin C) in tissues. Black cumin seeds (Nigella sativa) have been used as alternative medicine for more than 2000 years due to their multisystemic positive effects. Many active components of black cumin have been identified, including dithymoquinone, thymoquinone, nigellone, thymohydroquinone, nigilline, melanthin, nigelamine, damascenone, pinene, and p-cymene. Black cumin contains minerals such as calcium, magnesium, potassium, iron, phosphorus, cobalt, zinc, and manganese, and vitamins A, B, C, D, and E. Moreover, black cumin is rich in essential oils, proteins, alkaloids, saponins, flavonoids, and polyphenols. The black cumin has anti-inflammatory, analgesic, anthelmintic, hypocholesteremia, appetite stimulant, antidiarrheal, diuretic, antiulcer, spasmolytic and bronchodilatory, antimicrobial, antihypertensive, antidiabetic, anticancer, hepatoprotective, and renal protective activities and has antioxidant properties. This study was conducted to investigate the effects of black cumin on growth performance, antioxidant status, inflammatory responses, and biochemical and hematological changes in broilers under oxidative stress induced by hydrogen peroxide.

A total of 200 one-day-old chickens (Ross 308) were reared in the form of a completelyrandomized design with four treatments and five replications (10 chickens per replicate). Experimental treatments included: 1. Control group (fed with basic diet), and groups 2, 3, and 4 had levels of 50, 100, and 150 g of black seed per kg of diet. To induce oxidative stress, all birds received 1% hydrogen peroxide per liter of drinking water from 14 to 42 days of age. At 42 d, two birds were randomly selected from each cage and after blood sampling from the wing vein, were killed and dissected for liver and spleen tissue sampling. Growth performance, blood and biochemical parameters such as the number of red and white blood cells, hemoglobin, hematocrit, heterophil and lymphocyte, serum triglyceride, and cholesterol, as well as serum antioxidant parameters including the level of malondialdehyde (MDA) and the activity of antioxidant enzymes including glutathione peroxidase, superoxide dismutase, and catalase, were determined. In addition, liver enzymes present in the serum including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were measured. Also, to evaluate the effect of black cumin on the inflammatory response of broiler chickens under induced oxidative stress, serum interleukins including IL-10, IL-6, and TNF-α were measured.

The results showed that black seed supplementation in chickens under induced oxidative stress significantly improved the growth performance, increased the activity of antioxidant enzymes, and decreased MDA in serum, liver tissue, and spleen (P<0.05). Black seed supplementation significantly decreased serum levels of inflammatory cytokines of IL-6 and TNF-α, and increased anti-inflammatory cytokine of IL-10 (P<0.05). Also, black seed supplementation did not affect red blood cells, hematocrit, or hemoglobin, but increased white blood cells, lymphocytes, and decreased blood heterophils (P<0.05). Serum levels of triglycerides, cholesterol, ALT, AST, and ALP also decreased significantly under the influence of black seed.

Based on the results of this experiment, it appears that black cumin (Nigella sativa) seed supplement can improve the growth performance of broiler chickens due to its antioxidant and anti-inflammatory effects.