Before beginning to talk about the effects of antioxidant it is interesting to know the effects that oxidation produces in cattle.
There is a large number of studies that support that, despite the importance of oxygen for life, it also has a toxic effect on the body, known as the “oxygen paradox”, which occurs when free radicals (RL) are generated during mitochondrial respiration. To fight against these free radicals, the body responds with endogenous antioxidant substances, which attenuate the effects of this oxidation, and therefore eliminate these free radicals that are produced by the continuous metabolic reactions that occur in the body. But, at a certain moment, these endogenous antioxidants stop working, and one of these causes could be an excessive production of free radicals or weaken the effectiveness of this antioxidant, which would cause oxidative stress.
In addition, once the animal is sacrificed, these antioxidant effects begin to lose effectiveness and, for this reason, lipid oxidation, destruction of the muscle fibers of the meat, and rancidity of the meat begin.
Therefore, when there is an excess of free radicals, and the endogenous antioxidants are not able to eliminate them by themselves, it is necessary to administer exogenous antioxidants, which reduce cell damage or eliminate it.
Well-known are the effects they have on food, but also, little by little, the effects that can cause on the organism “in vivo” are known, since oxidative stress is the cause of a large number of pathologies in the animal including: sepsis, mastitis, enteritis, pneumonia, respiratory and joint problems.
Several studies have proven the importance of feeding animals with antioxidants and their relationship with oxidative stress, taking into account the importance in each stage. Therefore we can say that the antioxidant effect will not only positively affect the health status of the animals, but also, will add value to the quality of the final product (meat and milk)
Therefore, proper nutrition and correct environmental conditions will help to increase the antioxidant barrier, help a correct pregnancy without problems for the fetus and the mother and, in this adequate diet, the antioxidants will help to counteract the effects of many of the more frequent pathologies such as ketosis, hypocalcemia, mastitis, among others. In addition, the nutrients provided during the feeding of the animal will affect the composition of the meat and whatever it produces.
Next, the effects of antioxidants will be developed in periods of greater oxidative stress in cattle.
EFFECTS OF ANTIOXIDANTS IN CATTLE IN VIVO, ACORDING TO THE PERIODS OF GREATEST OXIDATIVE STRESS
We will analyze the effects of antioxidants in livestock according to the periods of greatest oxidative stress for the animal and according to its effects on the milk produced for food consumption.
According to periods of greater oxidative stress:
Labor and lactation in cows
The value of an animal is measured especially in what it produces, and among what is produced, we have milk. The quality of the milk could be measured according to the state of the cow, with the somatic cell count, but a recent study (Weiss WP, Antioxidant nutrients and milk quality, 2010) states that this vision of quality should be reviewed and expanded upon, since, according to him, the quality of milk can also be based on the amount of antioxidants it contains, since this amount of antioxidants will increase the shelf life of milk. It has been shown that dietary supplements (vitamin E, vitamin C, carotene and trace elements such as selenium, zinc or β-flavonoids, vitamin A and manganese key chain of enzymatic antioxidants) are useful to reduce the occurrence of infections in the udder and improve the quality of its production, in terms of fat, proteins, and the somatic cell count.
In ruminants, one of the stages where they are most susceptible to oxidative stress is the period surrounding the birth, since the cows need a lot of energy and have a large metabolic expenditure during lactation. Because of this, the importance of some antioxidants has been found for the health of the udder, uterus and reproductive capacity of the female and related diseases during the gestation period, proving improvement in births, the reduction of mastitis and the oxidative liver damage, a problem that normally increased during the birth. Even the increase in milk production in cows supplemented with Vitamin E and Selenium, and even administering antioxidants (α-tocopherol, retinol and β-carotene) two months before delivery can increase the immunity of the cow just before calving, and prevent the appearance of diseases.
It has been proven that high temperatures affect both the welfare of animals and their health and performance, these circumstances could be mitigated with the use of Vitamin E and Selenium.
Feed with high amount of highly fermentable carbohydrates
The administration of feed, with this high amount of highly fermentable carbohydrates, causes in the animal “ruminal acidosis” this acidosis affects productivity, and is the cause of many health problems in animals , as for example, laminitis.
There are data that give importance to antioxidants to improve the protection of the rumen, by decreasing metabolic acidosis. This is the case of vitamin E and selenium .
The use of antioxidants in dairy cows could help increase the amount of antioxidant nutrients in dairy products, in addition to helping improve the health status of animals for the reasons mentioned above.
The somatic cell count in milk can be an indicator of infections in the mammary glands, also known as mastitis, and also because of its importance in determining the quality of milk will determine the price of it. Hence the importance of improving the oxidative stability of milk, since they determine the hygienic quality of milk.
Antioxidants will help to improve this oxidative stability directly in milk and also, administered in vivo in animals, will reduce the number of somatic cells and plasmin (proteolytic enzyme that affects quality) in milk, by reducing the infection in the gland mammary, although this is still under study.
It has also been proven that the use of antioxidants in the animal, improves the lipid quality and the amount of lactose and cholesterol in milk
EFFECTS OF ANTIOXIDANTS IN THE POSTMORTEM LIVESTOCK
It could be said that meat is the product that is obtained after the death of the animal. This produces a series of changes that will determine the organoleptic quality of it. These factors will be tenderness, color, smell and taste.
Due to the oxidation of myoglobin (muscle protein) there are changes in both the color of the meat and the appearance of stale odors and flavors due to the degradation of the polyunsaturated fatty acids of the tissue membranes. This oxidative rancidity causes nutritional, sensorial and negative shelf-life qualities in the products
To avoid this alteration in the meat can be used antioxidants added, which will improve the shelf life and quality of the meat. Incorporating these into the feed for the daily diet of the animal, will have a triple positive effect on the meat, helping to slow lipid oxidation, also slowing down the color change and decreasing bacterial growth.
Directing animal feed based on antioxidants in their daily diets will help improve this oxidative stability, sensory qualities and also increases the nutritional antioxidant content that make up animal products, which is beneficial in human nutrition. In support of this claim, in the process of lipid oxidation, it has been found that it is easier for the antioxidant to be added to the cell membrane tissue during in vivo administration, than with the subsequent superficial addition directly to the meat.
APPLICATIONS OF ANTIOXIDANTS IN ANIMAL FEEDING
Although currently antioxidants are not used for their effectiveness “in vivo” and postmortem, they have been used by farmers to avoid animal stress and improve the quality of the final products.
The market is aimed at an intensive production and, therefore, this will affect the animal increasing its oxidative stress, which will cause an increase in the demand of antioxidants to reduce these effects.
In addition, taking into account the growing awareness among consumers of the benefits of antioxidant-rich foods, there is a great opportunity in livestock industries for the use of antioxidants.