Effects of Ferulago angulate extract on growth response, immune response and small intestine morphology of broiler chickens exposed to aflatoxin challenge

In most parts of the world, poultry are exposed to mycotoxins-containing foods. Aflatoxins are the most common mycotoxins formed primarily by the fungus Aspergillus. Fungi that produce aflatoxin can grow and multiply on different materials and under different conditions of humidity, temperature and pH (Mohammadi et al., 2015). A variety of additives, including organic acids, plant essential oils and extracts, probiotics, enzymes, vitamins, and minerals, have been tested to alleviate the negative effects of aflatoxins. Medicinal plant extracts contain active natural substances with antifungal and antioxidant properties that are able to reduce the toxicity of aflatoxins in food (Abdulmajeed, 2011). Ferulago angulate is one of the Apiaceae (Umbelliferae) families native to western Iran (Hosseini et al., 2012) that has been shown to have antioxidant properties and to improve the humoral immune system (Govahi et al., 2013). The aim of this experiment was to investigate the comparative effects of hydroalcoholic extract of Ferulago angulate (FAE), antifungal sorbate, probiotic, and vitamin-selenium complex (containing vitamin C, vitamin E, and selenium) on growth performance, immune response and intestinal morphology in broilers chickens challenged with aflatoxins.

A total of 350 one-day-old broilers (Ross 308) were distributed to 7 treatments with 5 replications/treatment in a completely randomized design. The experimental groups were: 1) negative control (NC; basal diet without any feed additive or aflatoxin B1); 2) positive control (PC; basal diet + 0.5 mg aflatoxin B1/kg); 3) PC + 1 g toxin binder/kg (TB); 4) PC + 1 g/kg probiotic PrimaLac (Pro); 5) PC + a vitamin-selenium complex preparation (ECSe; 200 IU vitamin E/kg feed + 250 mg vitamin C/kg feed + 0.2 mg selenium/kg feed); 6) PC + 200 mg/kg FAE (FAE200), and 7) PC + 400 mg/kg FAE (FAE400). Body weight gain and feed intake were recorded during starter (d 1 to 10), grower (d 11 to 24), finisher (d 25 to 42) and whole of the experiment (d 1 to 42), then the FCR was calculated. At the end of the experiment (42 d), 2 birds of each replicate were randomly selected and then slaughtered by Islamic method. Spleen, bursa of Fabricius and thymus weights were measured and relative weight to total BW of broiler chickens were determined. At 42 d of age, blood samples were collected from two birds in each replicate into vials containing EDTA to avoid blood clot formation. The values of hemoglobin (Hb) and hematocrit (Hct), red blood cell (RBC), white blood cell (WBC), as well as blood leucocyte profiles were measured. In order to assay the primary and secondary antibody responses against sheep red blood cell (SRBC), at 28 and 35 d of age, two birds per replicate were immunized intramuscularly with 1 ml of 2.5 % SRBC in PBS. Blood samples (1.5 mL/bird) were obtained from brachial vein at 7 d after each injection (d 35 and 42). For histopathological examination, the jejunal tissues of slaughtered broiler chickens (1 per replicate) were fixed in 10% of neutral buffered formalin, routinely embedded in paraffin, cut into 6-μm thick sections, and processed for hematoxylin and eosin staining.

The results showed that aflatoxin challenge adversely affected growth parameters; while treatments antifungal and FAE200 during the growing period and all additive-containing treatments during the finisher and whole experimental periods reduced the negative effect of aflatoxin on growth performance (P<0.05). The heterophil count and the heterophil to lymphocyts ratio were decreased by all dietary treatments than those determined in the PC group (P<0.05). All treatments, except probiotic, increased the values of red blood cells, white blood cells, and hematocrit as compared with PC group (P<0.05). The antifungal, probiotic and FAE400 treatments also increased the secondary IgG titer against sheep red blood cells in the aflatoxin-challenged birds (P<0.05). Furthermore, vitamin-selenium and FAE-containing treatments alliviated the negative effect of aflatoxin on villus surface area (P<0.05). According to a previous study (Hussein, 2015), the weight loss during aflatoxin challenge have been attributed to the toxic effects of mycotoxins on different cell organs, resulting in chickens refusing to consume toxins in their diets. It has been documented that the use of additives like selenium is used to remove fungi such as Aspergillus in poultry feed (Hatfield et al., 2012), which can explain the reduction of negative effects of aflatoxin on performance by vitamin-selenium mixture treatment in the present study. It is also reported that lipid peroxidation and the production of free radicals can cause damage to cell membranes during aflatoxicosis (Manafi and Khosravinia, 2013). Therefore, due to their antioxidant properties, vitamin C, vitamin E, and medicinal plants can prevent the production of free radicals in biological systems and thereby improve performance and health status under aflatoxin-inducing conditions. The phenolic compounds, especially polyphenolic compounds in the FAE have been reported to have a high ability to scavenge free radicals and thus can be used as a natural antioxidant in food and pharmaceutical industry (Hosseini et al., 2012). As a result, consuming FAE might reduce the impact of aflatoxin on growth performance, immune response and gut morphology, which is likely due to the antioxidant properties of this medicinal plant and its ability to scavenge free radicals caused by aflatoxin consumption.

In general, according to the findings of this study, Ferulago angulate extract, particularly at a dose of 400 mg/kg of diet, can improve growth performance, immune response, and health status during aflatoxin exposure, which appeared to be comparable to those recorded in the prebiotic and vitamin-selenium treatments. However, the growth benefits by Ferulago angulate extract were poorer than those recorded in the chickens fed with the NC and antifungal diets.