Role of phytobiotics in poultry and swine nutrition
Abstract
The trend in the use of phytobiotics in animal feed has been increased during last two decades. Due to the emergence of the problem of anti-microbial resistance and antibiotic residues in animal products led to raising the concern in using antibiotics as growth promoters and finally resulted in the ban on using in-feed antibiotics in most of the developed countries. As an alternative, phytobiotics were recommended by researchers and nutritionists. Plenty of studies have been done using phytobiotics in poultry and swine nutrition so far. They have mostly shown the antimicrobial, antioxidant, anti-inflammatory and growth promoting effects of phytobiotics. Antioxidative function of phytobiotics can positively affect the stability of animal feed and increase animal’s products quality and storage time.
Introduction
A major feature of poultry and swine production today is the reduction of in use of antibiotics and other allopathic medicinal products, largely due to concerns over bacterial resistance. Alongside this trend, however, is an ever-growing demand for low-priced, high quality food, improved feed hygiene, greater animal health and welfare, and reduced environmental impact.
Much research has focused on the development of alternative strategies to maintain poultry and swine health and enhance performance within intensive systems, and numerous substances, commonly known as natural growth promoters (NGPs) have been identified as effective alternatives to antibiotics. Phytobiotics are NGPs that have been growing in popularity as feed additives, due to their beneficial effect on gut health and immunity and growth performance.
Phytobiotics can be defined as plant derived products added to feed in order to improve performance. They originate from leaves, roots, tubers or fruits of herbs, spices and other plants. They may be available in solid, dried, and ground forms, or as extracts (essential oils). In simple terms, phytobiotics are products of plant origin, and preparations such as thyme, oregano, turmeric and garlic are gaining interest among researchers and poultry producers.
The beneficial effects of phytobiotics may arise from the activation of feed intake and the secretion of digestive enzymes, immune stimulation, antibacterial, coccidiostatic, anthelmintic, antiviral or anti-inflammatory activity, or from antioxidant properties. Many plant secondary metabolites, such as isoprene derivatives, flavonoids and glucosinolates, may act as antibiotics or as antioxidants in vivo. As a result of these beneficial effects, they lead to an increase in performance.
Phytobiotics produce their beneficial effects in several ways:
1. Growth promoting effect
Stimulating the secretion of digestive enzymes, improving palatability and flavour of feed, increasing feed intake, and increasing antimicrobial activity are some of the main modes of action of PFAs that might have led to the improved growth performance of poultry and swine.
2. Influence on palatability and gut function
Phytobiotics are mostly claimed to be beneficially effective on the flavour and palatability of feed, thus enhancing the production performance. They have beneficial impacts on the digestive tract (such as laxative and spasmolytic effects). In addition, they can prevent flatulence and stimulate digestive secretions such as saliva and bile. Also, PFA stimulates the secretion of mucus in the intestine which leads to reduction in adhesion of pathogens thus stabilising microbial eubiosis in the gut of animals.
Herbs develop their initial activity in the feed as flavour and, therefore, influence eating patterns, the secretion of digestive fluids and total feed intake. Stimulation of digestive secretions, including saliva, digestive enzymes, bile and mucus is often considered to be one of the important actions of phytobiotics.
A product from the rhizomes of Sanguinaria canadensis is frequently used in Europe for poultry while garlic and horseradish, when included in feed, stimulate the production of saliva and gastric juices. Turmeric, a powder derived from the rhizome of Circuma longa has been shown to improve feed intake in poultry when used at 0.25% in feed.
- Antimicrobial and coccidiostatic activity
Phytobiotics can selectively influence microorganisms through antimicrobial activity, or by a favoruable stimulation of the eubiosis of the microflora. This leads to better utilization and absorption of nutrients resulting in higher performance.
Various plant extracts, especially essential oils, have been studied for their antimicrobial properties. Phytogenic substances derived from oregano (Origanum vulgare), especially the major active substances thymol and carvacrol, are known to exert antimicrobial and bacterial actions in vitro, while eugenol, a component of the essential oil from cloves, has been shown to inhibit Salmonella typhimurium. Blends of oil containing thymol, eugenol, curcumin and piperin could be used to control Clostridium perfringens, the bacterium that causes necrotic enteritis.
The ability of hydrophobic essential oils to intrude into the cell membrane of pathogens, consequently disintegrating their membrane structures and causing ion leakage as a possible explanation of the antimicrobial activity of PFA. Decreasing the count of pathogens (e.g. Escherichia coli) in the guts of host animals can lead to increased count of beneficial bacteria (e.g. Lactobacillus) in the guts.
- Stimulation of the immune system
Polysaccharides derived from many plants play an important role in stimulating the growth of immune organs, such as the spleen, thymus and bursa, increasing the number and activities of many interdependent cell types such as T, B lympocytes, macrophages and natural killer (NK) cells, and enhancing cellular and humoral immune response.
Dietary addition of 200 g turmeric per quintal of feed significantly increased antibody production in response to sheep red blood cells inoculation of chickens. The persistency of antibody titre was better in birds fed turmeric in the diet. However, the antibody titre declined rapidly in those birds fed a diet that was not supplemented with turmeric.
- Antioxidant activity
The antioxidant activity of phytobiotics is another biological property of great interest. Their ability of scavenging free radicals may play an important role in preventing some diseases caused by free radicals, such as cancer and heart diseases. The ability of donating hydrogen or an electron to free radicals and also delocalising the unpaired electron within the aromatic structure are the main mechanisms of protecting other biological molecules against oxidation.
Other plant species such as ginger, curcuma, anise, coriander and plants that are rich in flavonoids (such as green tea) or anthocyanins (e.g. many fruits) also have antioxidant activities. The active compounds of phytobiotics may have protective roles for feed lipids against oxidative damage, similar to antioxidants such as α-tocopheryl acetate or butylated hydroxy toluene that is usually added to diets
Conclusions
Different aspects of PFAs have been studied in the last two decades. Growth promoting effect, antimicrobial activity, antioxidant activity and anti-inflammation activity are some of the functions that have been investigated. According to the literature, phytobiotics have positive effects in improving the performance of poultry and swine. The improving effects of dietary supplementation with PFA are partially associated with enhanced feed consumption probably due to improved palatability of the diet. Regarding the antimicrobial activity, there is some evidence supporting the assumption that the general mode of action of PFA is by modulating gut microflora and reducing intestinal pathogen pressure. Comparing antimicrobial feed additives and organic acids with PFAs that are currently being used in poultry and swine feed, shows similar modulation effects for relevant gastrointestinal factors such as microbiota, fermentation products (including undesirable or toxic substances), nutrients digestibility, gut tissue morphology, and reactions of the gut-associated lymphatic system. However, due to the wide variety of available phytogenic products, the recommended effective dosage varies. Furthermore, some studies have shown that phytobiotics can enhance the digestive enzyme activity and absorption capacity. In addition, the results of some studies have demonstrated that phytogenic products may be able to stimulate intestinal mucus production which may further contribute to the relief from pathogen pressure through inhibiting adherence to the mucosa. Since most experimental results are available only for commercial products containing blends of phytogenic substances, there is still a need of using a systematic approach to explain the efficacy and the mode of action for each type of PFA and the dose of active substances. Nevertheless, the available documents to date in feeding such compounds to swine and poultry seem to justify the assumption that PFA may have the potential to promote production performance and productivity as non-AGPs.
Reference-https://www.tandfonline.com/doi/full/10.1080/1828051X.2017.1350120
Sandeep Kumar* and Ramsawroop
PhD Scholar, Department of Animal Nutrition
Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana – 125004
*Corresponding author: drskverma05@gmail.com
