Fighting radicals – the versatility of antioxidants
Antioxidants in feed neutralise not only oxygen and its reactive compounds (ROS), but are also able to intercept substances which have an oxidising effect in general, in particular free radicals of varying origin.
Apart from preserving fats and oils, antioxidants are also on everyone’s lips in the field of health. ‘Superfood’ and ‘green smoothies’ are the keywords whereby particular emphasis is placed on the health benefits. In medical literature it is known and undisputed that a multitude of oxidative and anti-oxidative processes take place at cellular level.
Free radicals also develop here and a complex cellular protective system is in place to ward off potential damage. It is equally known that this system can lose its balance, and this can have severe physiological consequences.
Preserving feed – a question of the right mix
BHT, BHA, EQ or propyl gallate are mainly used in feedstuffs, often in combination with vitamins or organic acids. Antioxidants differ in their responsiveness and provide different advantages. With mixtures, however, one thing is particularly salient: the effects of the individual components do not just simply add up.
Certain combinations show synergetic effects, as radical formation takes place over several stages during which antioxidants influence each other. The feed matrix itself provides highly individual milieus for different antioxidants. With the aid of much knowledge and experience inclusion rates can be optimised without jeopardising feed quality. In addition, manufacturers, such as Lohmann Animal Nutrition, are attending to alternatives, e.g. the registration of TBHQ in the EU.
Physiological significance – oxidative stress in the cell
Natural antioxidants are part of the cellular radical defence system. It is estimated that for every Low Density Lipoprotein there are approximately 7 molecules of α-Tocopherol that prevent the oxidation of biological units in the cell. Free radicals in cells can denature proteins or even damage DNA directly which leads to incorrect protein folding and ER stress. The system reacts medium-term by suppressing protein biosynthesis, while in the long-term the system switches to programmed cell death. The cause for an excess of radicals can be increased metabolic load, occurring, for example, as a result of NEB or subclinical inflammatory processes.
The entry of ROS via the feed ration is also a cause of oxidative stress. Particularly recommendable as effective feed additives are secondary plant substances, especially those from the category of polyphenols and carotenoids, as these also have positive effects on inflammatory processes in addition to their antioxidative properties.
Various trials in dairy cows show a significant improvement of energy corrected milk (ECM) and various typical markers of ER stress following supplementation with secondary plant substances in the TMR. The concentrations for this differ, however, (0.02% versus 4.3%), and also heat stability can be an important factor. If the aim is to provide the metabolism with targeted support via the feed ration, then suitable substances must be selected in an equally targeted way.
Improve a lot with less effort
Antioxidants are used to preserve feed, but are also useful in the metabolism of the animal. With the right combination of antioxidants, optimised according to the feed matrix, it is possible to lower the inclusion rate and the costs whilst increasing the protective effect at the same time. Performance and cellular stress can be positively influenced by selected plant antioxidants. These also support the maintenance of physiological balance in the animals. Antioxidants remain a fascinating topic.
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