The Effect of Sour Tea (Hibiscus sabdariffa) Plant Extract on Immune System, Plasma Antioxidant Status, Oxidant Balance and Blood Biochemical and Functional Parameters of Old Laying Hens

Stress increases the need for antioxidants, decreases eggs production and weakens immune system of laying hens. Since there is insufficient knowledge about overcoming natural stress conditions with minimal cost and side effects in old laying hens, the medicinal herb contained flavonoid and polyphenolic compounds are concerned. Apart from estrogenic, antibacterial effects and cholesterol reduction property that will result to lower cholesterol deposition in poultry products and where calyx and leaf of Hibiscus sabdariffa
are known as potent antioxidant. Therefore, these experiments were designed to investigate the effect of Hibiscus sabdariffa extract as natural antioxidants on the immune system, blood biochemical parameters, plasma antioxidant status and the antioxidant balance of laying hens during molting and post-molting periods, also, laying performance and egg yolk cholesterol in the second phase of laying hen egg production.

In these experiments, aqueous-alcoholic extract of calyx and leaf of Hibiscus sabdariffa were prepared and sprayed on feed at levels of 300 and 700 mg/kg. One liter of %96
ethanol/distilled water mixture (30:70) were used to infuse 100 g each of the plant material (calyx or leaf) for 24 h. During the pre-experimental stage, minerals composition and antioxidant properties of Hibiscus sabdariffa were measured. Each of the main experiments, were conducted with 200 laying hens in a completely randomized design. In both experiments, five treatments consisted of control diet (basal diet), basal diet with 300 and 700 mg/kg of leaf extract of Hibiscus sabdariffa and basal diet with 300 and 700 mg/kg Hibiscus sabdariffa calyx extract. In both experiments, the blood cholesterol, total protein, triglyceride, LDL, HDL, glucose and malondialdehyde were evaluated by Spectrophotometer auto analyzer. In the end of each experiment, immune system and plasma antioxidant status for 2 samples from each replicate were determined. The egg production, egg weight, egg mass, feed intake and feed conversion ratio were recorded weekly. The egg malondialdehyde was determined during post molting period. In order to measure the level of yolk cholesterol and triglyceride, in the end of the experimental period, 2 samples were randomly taken from each replicate and after separating the yolks and mixing them, were analyzed by Spectrophotometer auto-analyzer with enzymatic method. The data were statistically analyzed with the general linear model by SAS software. The
mean differences between treatments were studied by Tukey's test.

Although there was more vitamin C in the leaf compared to calyx, the antioxidant activity including total antioxidants, phenols and anthocyanins in calyx were higher than
leaf. In both experiments, plasma antioxidant status of laying hens in a dose-independent manner were improved. During post molt period, attempt to increase oxidative stability of plasma and egg yolk also, improving plasma antioxidant status by dietary supplementation of Hibiscus sabdariffa extract was not significant, however, the Hibiscus sabdariffa calyx at 300 and 700 mg/kg levels, significantly affected plasma MDA and total antioxidant capability during molting period. In both experiments, the relative increase in antibody titers and the ratio of heterophil to lymphocyte were observed by all treatments as compared to the Control treatments. Hibiscus sabdariffa showed to have no significant effect on performance parameters. Probably, the negative effect of polyphenol compounds found in Hibiscus sabdariffa on digestive enzymes decreased lipid, protein and carbohydrates digestibility, thus reduced feed intake, egg weight and total blood protein, insignificantly, blood glucose and cholesterol, significantly. Also, the Hibiscus sabdariffa, especially leaf, decreased the yolk cholesterol and triglyceride. On the other hand, supplementation of Hibiscus sabdariffa at 700 mg/kg, improved production performance following feed conversion ratio compared with Control treatment that's probably due to quercetin and daidzein phytoestrogens found in Hibiscus sabdariffa. It seems that some compounds in Hibiscus sabdariffa, including phytoestrogens and organic acids that has been reduced the negative effect of other Hibiscus sabdariffa components on the performance of laying hens.

It can be concluded that Hibiscus sabdariffa, especially its leaves, which are discarded in most countries, including Iran, have the significant beneficial effects, such as anti-lipid effects, improvement of total plasma antioxidant and oxidative balance of old laying hens, with minimal cost and no significant negative effect on functional and immune parameters. It seems that finding of effective dose of Hibiscus sabdariffa is important to achieve layer hens’ maximum efficacy according to the test conditions and can economically be extended the range of its usage.