An antioxidant is a substance that when present in food at a concentration lower than that of the oxidizable matrix, is significantly capable of interrupting or preventing its oxidation, Halliwell and Gutteridge (1999).
Antioxidants are used as additives to prolong the shelf life of animal feeds, premixes and fats, based on their effect to prevent lipid peroxidation and oxidative rancidity during their production, processing and storage.
Due to the current trend of the formulation of diets with ingredients rich in polyunsaturated fatty acids (PUFAs), which are highly susceptible to lipid peroxidation, the use of antioxidants in animal nutrition has been increased.
Technological role of antioxidants in animal nutrition
The oxidation of fats and oils that make up the feed causes a notable decrease in its nutritional value by reducing the energy provided to the animal that ingests them. In the same way the feed that has suffered the oxidation of its components contains high levels of free radicals and peroxides that can become toxic to animals.
Antioxidants contribute to keeping feed, flours, premixes and animal fats, fresh and healthy, allowing them to be preserved for longer, because the antioxidants protect them from the deterioration caused by oxidation, keeping their sensory characteristics intact, thus preventing their rancidity and discoloration.
The use of antioxidants in animal nutrition helps preserve the sensory qualities of feed and prevents the destruction of essential nutrients such as pigments, amino acids and vitamins. (Calabotta and Shermer, 1985).
Companies are constantly looking for new antioxidants that are safe for health, economically viable and above all that do not modify the organoleptic properties. They must also be effective at low temperatures, liposoluble and resistant to the treatments to which feed is subjected.
Biological function of antioxidants in animal nutrition
Antioxidants have the mission of evading the oxidation of substances that can cause physiological alterations and play a basic role in the prevention of diseases derived from oxidative stress.
In essence, oxidative stress is the deteriorating condition which results from the imbalance between the generation of endogenous free radicals and the biological systems of antioxidant defense in the body (Halliwell and Gutteridge, 1999). In situations of excess production of free radicals, there is a great need for an exogenous intake of antioxidants to prevent possible cellular damage. The exogenous antioxidants play a fundamental role in the balance between oxidation and antioxidation. In most circumstances, physiological doses of antioxidants exert beneficial effects (Kawanishi et al., 2005, Bouayed and Bohn, 2010).
The animals have an antioxidant biological system to combat free radicals that are continuously produced as a result of their own metabolic activities.
However, there is a certain limit to the protection offered by the endogenous antioxidant barrier. This limit is further compromised by the presence of factors that could cause excessive production of free radicals and / or weaken the effectiveness of the antioxidant biological system, thus causing oxidative stress. Some of these factors are: the consumption of feed with high content of polyunsaturated fatty acids, the intake of mycotoxins, heavy metals, fungicides and pesticides, poor nutrition and pathogenic infections.
Antioxidants are essential to optimize animal yields destined to livestock production, not only to obtain a higher economic yield, but also to increase the quality of production (milk, meat, eggs, …) and consumer safety. Through nutrition we find an economical, practical and effective way to administer antioxidants to animals. (Sebastián, 2003).
Certain antioxidants, such as Tocopherols, besides protecting products technologically, have a biological benefit of containing in their composition alpha tocopherol (Vitamin E). The Tocopherols are formed by a mixture of 4 isomers: alpha, beta, gamma and delta, and the percentage of each of them varies depending on the origin of said Tocopherols.
Profile of isomers in Soybean and Sunflower Tocopherols
|Alpha Tocopherol||Min 5%||Min 65%|
|Beta + Gamma Tocopherol||Min 60%||Min 7%|
|Delta Tocopherol||Min 18%||Min 9%|
It has been proven that using different doses of d-alpha tocopherol in the diet of ruminants has produced positive effects by reducing the incidence of diseases (Huerta et al., 2005). By supplementing dairy cows with antioxidant vitamins, the incidence of mastitis infection has been reduced. (Castro and Márquez, 2006).
Vitamin E supplementation has also improved the meat quality of the slaughtered animals since the color of the meat is maintained compared to that of animals whicj have not been supplemented, because there is no accelerated oxidation of oxymyoglobin in metamyoglobin, a protein that gives the organoleptic characteristics to meat (Huerta et al., 2005).
Although the addition of antioxidants in food processing has been used for a long time, antioxidant supplementation in animal nutrition may be a more effective strategy to improve oxidative stability, sensory qualities and the antioxidant nutritional content of animal products, while being more economical.
The intake of feed to which antioxidants have been added delays the formation of metamyoglobin in meat intended for human consumption and prolongs the period when the muscle surface shows no evidence of discoloration.
All the antioxidants that are used in the EU are tested in laboratories, one by one, in order to check, before allowing their use, that they do not harm the animal’s health. In most cases, once authorized, their use is limited to specific quantities and certain foods. EU standards also require that all food additives (of which antioxidants are a part) clearly appear on the product labeling.
In summary, antioxidants in animal nutrition are very important in the conservation of essential nutrients and their best use by the animal. In addition, the presence of antioxidants in animal nutrition increases animal welfare and improves the quality of products of animal origin.