The term “nutraceutical” was coined from “nutrition” and “pharmaceutical” in 1989 by Stephen DeFelice, MD, founder and chairman of the Foundation for Innovation in Medicine (FIM), Cranford, NJ. According to DeFelice, nutraceutical can be defined as, “a food (or part of a food) that provides medical or health benefits, including the prevention and/or treatment of a disease”. In other words, nutraceuticals are chemical or natural feed ingredients which may enhance health by providing a physiological benefit by the provision of basic nutrients. Enzymes, prebiotics, probiotics, yeast and fungal extracts, predigested hydrolyzed carbohydrates and fats, phytogenic additives, acids etc are included in nutraceuticals. However, the term nutraceutical as commonly used in marketing has no regulatory definition.

Feed accounts for a major portion of farm expenses in livestock and poultry production. Thus, to obtain maximum profitability, it must be ensured that the feed should not only be well balanced nutritionally but economical too. Rising prices of feeds certainly have reduced the profitable nature of broiler farming. For better utilization of feed and to improve feed efficiency, antibiotics were used at sub-therapeutic levels in the animal ration. Development of antibacterials progressed very quickly and as a result, certain new antibacterial substances were discovered and developed for use as growth promoting agents in livestock and poultry. The antibiotics act by reducing nutrient destruction in the intestine, increasing microbial synthesis of certain vitamins and amino acids, reducing the rate of passage of nutrients in the gastrointestinal tract and reducing the thickness of the intestinal wall. This thinner wall and reduced rate of passage have been suggested as factors favoring efficient absorption of nutrients. It is also reported that the antibiotics also inhibit the bacterial production of ammonia and other harmful nitrogenous compounds such as trimethylamine that reduce the growth of chickens.

The increasing use of antibiotics in livestock and poultr y led to development of antibiotic resistant micro organisms and antibiotic residues in livestock products besides other side effects. These caused alarm bells ringing all over the world and by the end of June, 1999 majority of antibiotics as growth promoters in monogastric diets had been banned within the EU. The ban on use of antibiotic at sub therapeutic level in Europe and the potential for a ban in the United States have made scientists to seriously think of alternatives to antibiotics. In fact, the use of probiotics for farm animals was already stimulated by the findings of the Schwann Committee in 1969 which recommended that antibiotics in animal feeds should be restricted. However, the concept of probiotics gained momentum in later part of the last century. In recent years, with the public disapproval of using antibiotics in livestock and poultry production due to their residual effects in their products, there has been a greater emphasis on the use of probiotics in poultry.

Prebiotic foods have been consumed for centuries, either as natural components of food, or as fermented food. However, interest in dietary use of prebiotics blossomed in the later 1800s and early 1900. Preliminary researches revealed that lactose had a profound effect on the pH of the caecal contents and intestine due to lactic acid fermentation resulting in enhanced calcium and phosphorous absorption. Further, it was also noted by several workers that inclusion of lactose in poultry diets resulted in better growth and reduced mortality. A prebiotic can be defined as “a non digestible food ingredient that beneficially affects the host by selectivity stimulating the growth and/or activity of one or limited number of bacteria in the colon, and thus improves host health” (Gibson and Roberfroid, 1995). Based on this definition, Russell (1998) formulated the criteria according to which a substance can be a prebiotic. First, prebiotics are always feed ingredients that are not digested by the host, not or little used and/or metabolised as they pass through the upper portion of the intestinal tract, so they can reach the f lora of the large intestine. Secondly, they have to be able to serve as a substrate for one or more bacterial species with a potentially beneficial effect on the host. Finally they have to be able to cause a shift in the microf lora that improves the health of the host. In principle only non-digestible, fermentable feed components are prebiotics.

Feed accounts for a significant cost of production in livestock and poultry. In case of poultry, it represents 65% cost of the production in broilers and 75% in layers. Presently the live stock industry faces a huge challenge due to the high cost of feed ingredients and shortage of the conventional feed ingredients. Over the years, efforts have been made to use unconventional feed ingredients. However, such feed ingredients have many anti nutritional factors that adversely affect the performance of livestock and poultry. Due to the presence of these incriminating factors, the unconventional feed ingredients are poorly digested in livestock and poultry. These poorly digested feed ingredients results in bacterial overgrowth, which becomes a potential substrate for bacterial fermentation leading to intestinal disorders and disease. Application of antibiotics and other anti-microbials help to overcome the ill effects. However, the ban on the use of sub therapeutic level of antibiotics in many countries has increased the relevance of use of exogenous enzymes in the feed of livestock and poultry. These exogenous feed enzymes improve the nutritive value of different feed stuffs, economize livestock and poultry rearing and reduce environmental pollution.

An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. However, sulphuric acids, containing the group –SO2OH, are relatively stronger acids. Alcohols, with –OH, may also act as weak acids. Some other groups may also act as weak acids viz. thiol group and phenol group. In biological systems, organic compounds containing these groups are generally classified under organic acids. Some common organic acids are lactic acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, propionic acid and butyric acid. Organic acids have been used for decades in commercial compound feeds, mostly for feed preservation, for which formic and propionic acids are particularly effective. Since the ban of antibiotic growth promoters in many countries, organic acids have been used increasingly, not only because of their preservative qualities, but also for their nutritive properties. Organic acids and their salts are generally regarded as safe and have been approved by most member states of EU to be used as the feed additives in animal production.

Fats are rich sources of energy. Fats provide 2.25 times more available enrgy than carbohydrates. Fats also increase the palatability and reduce the dustiness of feed. Fats and fatty acids decrease the heat increment in the body. Fatty acids are also involved in number of physiological functions of the body. Recently, considerable interest has been shown on studies pertaining to dietary supplementation of polyunsaturated fatty acids (PUFA) in animal feed and their role in animal health and production.

Phytobiotics are plant derivatives such as herbs, plant extracts or spices and have a wide range of activities such as stimulation of feed intake, growth and endogenous secretions in the gut. They act as immunomodulators resulting in decreased mortality and also have coccidiostatic, anti microbial, anthelminthic and anti-inf lammatory activities. Phytobiotics also possess hepatoprotective and hepatogenic properties, which tone up liver resulting in increased nutrient utilization and better performance. Herbs like Achyranthes aspera (Prickly Chaff Flower, Devil’s Horsewhip, Apamarga), Andrographis paniculata (Green chirayta, King of bitters, Kalamegha), Azadirachta indica (Neem), Boerhaavia diffusa (Spreading Hogweed, Punarnava), Eclipta alba (False Daisy, Bhringaraj), Ichnocarpus frutescens (Black creeper, Utpalagopa), Terminalia chebula (Black myrobalan, Haritaki). These herbs have hepatostimulant, hepato-protective, immunomodulatory and antioxidant activities (Sadekar et al., 1998; Manu and Kuttan, 2009; Michels et al., 2011, Dash et al., 2007). Further, they optimize digestion and metabolism resulting in better protein utilization, improved mucosal function and reduced cost of metabolic deamination. Andrographolide and 14-deoxy-11, 12-didehydro-andrographolide isolated from Andrographis paniculata inhibits free radical activities and lipid peroxidation. Inhibition of lipid peroxidation in meat prevents free radical production thereby preserving meat composition, colour and improvement in shelf life. In addition, it has been studied that a herb Terminalia chebula helps to reduce stress (Selvakumar et al., 2007).