Natural feed additives for meat chicken
The most promising herbs that could be used as replacements for antibiotics include dill, oregano, ginkgo, sage, fennel, olive leaves, hogweed, coneflower, savory and some Chinese medicinal herbs.
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1. The dill plant (Anethum graveolens L.) from the Apiaceae family contains glycosides, saponins, tannins, terpenoids, steroids, flavonoids, phlobatanin, cardiac glycoside, anthraquinone, gallic acid, catechin, chlorogenic acid, luteolin and epicatechin. It has valuable health benefits, being able to reduce coliforms and increase lactobacilli in the caecum and jejunum. Feeding 0.4 and 0.6% dill in the diet of broiler chicks has the potential to improve performance, reduce cholesterol and triglycerides, and improve microbial flora. Oregano (Origanum compactum) is also potentially very useful, with carvacrol as one of the major active ingredients. It is effective against Escherichia coli and salmonella species in the caecum of broilers. Another major active ingredient is thymol, which has similar effects.
2. Skullcap (Scutellaria baicalensis), a Chinese herbal medicine, is an additive that has attracted considerable attention. Flavones and other antioxidants can be extracted from the roots, with the main active compounds being wogonoside and aglycones baicalin. In low doses, the main benefit of this herbal additive is in reducing heat and other stresses. However, the inclusion of Scutellaria baicalensis root (SBR) at levels of 1 and 1.5% in poultry diets has been observed to reduce the size of the spleen and Bursa of Fabricius, as well as reducing lymphocytes and eosinophils.
Another common Chinese medicine herb, Ginkgo biloba (GB), has antioxidant, anti-apoptotic, anti-diabetic, anti-asthmatic, neuroprotective, cardiac protective and antitoxic benefits. Fermented Ginkgo biloba probiotics (FGB) included at 0.2 and 0.4% in the diet can improve the growth and immunity of broilers while suppressing the pathogenicity of Escherichia coli. The addition of Ginkgo biloba (0.06%) and peppermint (0.2%) in feeding broiler chickens under heat stress can improve the efficiency of feed conversion and increase the immune response against Newcastle Disease and infectious bronchitis viruses [54]. Feeding both Bacillus coagulans-fermented Ginkgo biloba (FG) and nonfermented Ginkgo biloba (NFG) forms to broiler chickens at 0.3% of the diet can affect Newcastle disease vaccine potency. The FG form increased the expression of antimicrobial defensin RNA, while the NFG form inhibited this vaccine.
Learn More3. Sage (Salvia officinalis L) is a commonly used Mediterranean herb, which has some control of Escherichia coli in chickens. It has also led to increased eosinophil, monocyte and, heterophil and immunity titers against Newcastle disease and avian influenza viruses, at concentrations in the diet of 0.5 to 1.2%. The effects of sage extract on immune parameters and antibacterial activity in broilers are promising.
4. Fennel is another Mediterranean herb, whose extract has improved the effectiveness of vaccination against Newcastle Disease and increased immunoglobulin production [58]. In Safaei-Cherehh et al.’s study [58] fennel extract also improved resistance to infectious bronchitis virus, but it reduced it to infectious bursal disease.
5. The olive tree (Olea europaea L.) is one of the most relevant Mediterranean phytogenics, and olive leaf extract has anti-hypertensive, anti-atherogenic, anti-inflammatory, blood sugar lowering, and blood cholesterol lowering properties. These extracts contain many potentially bioactive compounds, especially phenolic acids, phenolic alcohols (hydroxytyrosol), flavonoids, and secoiridoids (oleuropein). The phenolic compounds of olive oil help by positively regulating the expression of genes involved in maintaining tight junctions between intestinal cells, modulating the oxidative state of the intestinal epithelial layer, inflammatory and immune response, and maintaining the integrity of the intestinal barrier. In addition, phenolic compounds extracted from olive leaves may be beneficial for broilers as antioxidants and through their antimicrobial activity against intestinal pathogenic bacteria. Care has to be taken as leaves can have a high copper content from copper fungicides, which in the long term can damage the liver of consumers. About 25% of the leaf is oleuropein, which has antioxidative, antimicrobial and antiviral properties, and functions in the leaf to protect against insects and UV light. Olive tree leaves also have a much higher phenol content than olive oil, with greater antioxidant potential. Supplementation with olive leaf extract up to 25 mg/kg improved epithelial barrier function in experimental colitis models, as demonstrated by increased expression of mucin MUC-2, tight junction protein ZO-1 and TFF-3. The intestinal anti-inflammatory activity of olive leaf extract in murine colitis models may be related to its immunomodulatory properties and capacity to restore the intestinal epithelial barrier.
6. Hogweed (Heracleum persicum) is a plant in the carrot family, whose extract has antioxidant, anticonvulsant, analgesic, anti-inflammatory and immunomodulatory activities. These are attributed to a wide range of phytochemical compounds, including volatile compounds, terpenoids, triterpenes, furanocoumarins, flavonoids and alkaloids. A Heracleum persicum supplement at levels between 1 and 2.5 ml/L can improve the function of the immune system in broiler chickens. Additionally, feeding levels of 0.5 and 0.75% hogweed led to an increase in the titer against avian influenza and the microbial population of Lactobacillus and a decrease in Escherichia coli in the ileum. When included at levels of 100–200 mg/L, the extract of this plant increases the antibody titer of broilers against Newcastle disease virus. The reason for these health-giving properties could be the presence of flavonoids or furanocoumarins in the H. persicum plant, leading to an increase in humoral immunity. Heracleum persicum extract can also stimulate macrophages and beta lymphocytes that play a role in antibody synthesis.
7. The purple coneflower (Echinacea purpura) can increase lymphocytes and reduce heterophils, in conjunction with an antibiotic, probiotic, organic acid, and vitamin C [69]. Summer savory (Satureja hortensis L.) and its extract have widespread antimicrobial properties and can reduce the concentration of Escherichia coli in the digestive tract.
8. The thyme plant (Thymus vulgaris) increases growth in broiler chickens, but there is some evidence that it does not improve immunity. In support of this, Belali et al. found no effect of thyme extract on broiler immunity, but it did increase the growth rate. However, there are many other reports of improved immune function with the addition of thyme or thyme oil to broiler diets, e.g., Fallah and Mirzaei found that it improved antibody titers to Newcastle disease and influenza
8. The chicory plant (Cicorium intybus L. in the Asteraceae family), considered by most to be a herb, contains fructooligosaccharides, inulin, coumarins, and flavonoids. When added to the diet of broilers it improves the immune system in the ileum, which has more lactobacilli and reduced Escherichia coli populations. Similar benefits have been attributed to pennyroyal (Mentha pulegium L.), although in the jejunum, rather than the ileum, and improved resistance to Newcastle disease has been recorded [4]. Yarrow (Achillea millefolium var. occidentalis) included at 0.5–1.5 g/kg in the diet has produced either no effect or increased lactobacilli and reduced Escherichia coli in the ileum.
Read also: Silkworms: sustainable source of nutrition for broilers
Feed Additives from Spices
Spices that could be used as alternatives to antibiotics include ginger, cinnamon, coriander, cumin, garlic and red and black pepper [15]. Ginger (Zingiber officinale roscoe) contains several active compounds including gingerol, shogaols, gingerdiol and gingerdione [4,75]. The oil extract from ginger contains a high proportion of sesquiterpenes (67%), monoterpenes (17%) and aliphatic ingredients (14%) [75]. It has a strong antioxidant, antimicrobial and antifungal activity in the gut, greater than that of turmeric [75,76]. However, when included at 0.5–1.5 g/kg in the diet it has produced mixed results on immunity, with high level doses destroying the gut microflora, but smaller doses having some control of pathogens in the gut. Both ginger and garlic (Allium sativum) are active against Escherichia coli, though garlic has broader spectrum activity. The mechanisms are enhancement of phagocytosis and bactericidal activity and reduction of NO production. Many other plants in the allium genus have antimicrobial properties, with more than 100 phytotherapeutic compounds, including alliin, allicin and allyl isothiocyanate .
1. Coriander (Coriandrum sativum L.) is both a herb and a spice. The seed and coriander extract contain several beneficial pharmaceuticals, which potentially have antibacterial, antioxidant, antidiabetic and hypolipidemic properties [78]: linalool (67.70%) and α-pinene (10.5%); γ-terpinene (9.0%); geranyl acetate (4.0%); camphor (3.0%); and geraniol (1.9%). It has been suggested that this alone can effectively replace synthetic antibiotics in the diet of poultry. Improvement has been observed in the antibody titers against common diseases, such as Newcastle, infectious bronchitis, and bursal disease infections in birds receiving coriander extract in water (1000 and 1250 ppm of coriander extract and 2 and 2.5% coriander powder) and also in birds receiving a combination of 2% coriander seeds and 0.5% black pepper.
A plant native to Iran and Turkmenistan known as galbanum (Ferula gummosa boiss), from the Apiaceae family, produces oleo gum resin. The resin potentially protects against gram-negative bacteria [82], with an increased immune response to Newcastle disease challenge and increased spleen weight when 1% galbanum was included in the diet of broilers.
2. Sumac (Rhus coriaria L.) is a plant species belonging to the Anacardiaceous family, and its fruit contains active compounds of flavonols, phenolic acids, hydrolyzable tannins, anthocyanins and organic acids. Sumac seed powder (SSP) is produced by grinding dried fruits and has defensive benefits for many health-related problems, including reducing Escherichia coli and strengthening health [83,84].
3. Black cumin (Nigella sativa L.) contains bioactive compounds, nogelleone, thymoquinome, and thymohdroquinone, giving it anti-toxic and antimicrobial properties and increasing the defense mechanisms against infectious diseases. At high doses, black cumin improved antibody titers against Newcastle Disease and it was particularly effective against salmonella species.
4. Fenugreek (Trigonella foenum-graecum L.) also increases antibody titers. Fenugreek is more effective than rosemary at immunological control in broilers.
Read also: Tips for managing poultry vaccine reactions
5. The clove plant, a common spice, is rich in eugenol, an antibacterial agent. In chickens, it has the ability to reduce the prevalence of pathogens in the intestine and increase the size of the spleen [89]. The chili pepper (genus Capsicum, family Solanacea) contains dietary capsaicin, which prevents high-fat diet-induced metabolic endotoxemia and chronic low-grade systemic inflammation by increasing cecal butyrogenic bacteria and consequently butyrate levels, inhibiting colonic cannabinoid receptor type 1 (CB1) and reducing LPS biosynthesis. Therefore, capsaicin prevents intestinal dysbiosis and metabolic endotoxemia, which are associated with chronic inflammatory diseases, and it plays a role in improving immunity. Capsaicin increases the ratio of Firmicutes/Bacteroidetes and the abundance of Faecali bacterium. In addition, it increases the plasma level of glucagon-like peptide-1s(GLP-1) and gastric inhibitory polypeptide (GIP), and decreases the plasma ghrelin level. Poultry do not feel the heat of capsaicin in the same way as humans, due to the lack of specific receptors to bind capsaicin or the lack of capsaicin-sensitive receptors. However, it stimulates the immune system. In broiler chickens, a supplement of 80 mg/kg of natural capsaicin extract in diets improves antioxidant status and immune function. Capsaicin extract decreased the serum concentration of TNF-α and IL-1β and increased the total antioxidant capacity of catalase, glutathione peroxidase, and superoxide dismutase.
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