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Jaylor: Oxidative Stress in Dairy Animals


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It’s hard to attend a dairy meeting these days without hearing the term “oxidative stress” at least once. But very few people, nutritionists included, have a full understanding of the term. Learn more here.

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Jaylor: Oxidative Stress in Dairy Animals

  1. 1. Oxidative Stress in Dairy Cows
  2. 2. Oxidative Stress in Dairy Animals It’s hard to attend a dairy meeting these days without hearing the term “oxidative stress” at least once.But very few people, nutritionists included, have a full understanding of the term.
  3. 3. What is Oxidative Stress? In the cow’s body there is a natural balance between the formation of free radicals during the normal metabolism of the cells and the internal antioxidantcapacity of the animal that would prevent free radicals from accumulating and harming the cells. Free radicals are atoms, molecule, or ions with unpaired electrons. Free radicals may have positive, negative, or zero charge. These unpaired electrons cause radicals to be highly chemically reactive.
  4. 4. What is Oxidative Stress?
  5. 5. What is Oxidative Stress? In situations where the levels of free radicals exceedthe antioxidant capacity of the animal, oxidative stress occurs. High-producing dairy cows are prone tooxidative stress, and the situation can be exacerbatedunder certain environmental, physiological and dietary conditions. Free radicals can damage the cells by oxidizing the essential fatty acids of the lipid membranes, protein and DNA structure. This will impair production and compromise health status of the animal.
  6. 6. What is Oxidative Stress? Dietary lipids such as supplemental fat, oil seeds and distiller grains if not stabilized can be significant contributors to the load of free radicals in the animalin addition to their negative effect on rumen microbial growth. Once critical structural damage occurs, antioxidants may no longer be able to repair the problems.Therefore, it is crucial that dairy producers understandthe need for proper balance and the role that nutrition plays.
  7. 7. What is Oxidative Stress?
  8. 8. What is Oxidative Stress?A cow with a large amount of oxidation occurring willhave more tissue damage and it will have an increased cost of maintenance. This cow will be spending a larger proportion of its energy fixing and repairing processes and tissues, rather than producing and reproducing.
  9. 9. Oxidative Stress in Dairy AnimalsDietary antioxidants (by protecting dietary lipids from being oxidized in the final feed and digesta) can reduce the damage of free radicals to rumen microorganisms, the feed and digesta and therefore reduce the damage of free radicals to rumen microorganisms and the animal.
  10. 10. Oxidative Stress in Dairy Animals In dairy cattle, commercially available dietary antioxidants have been shown to improve fiberdigestibility in the rumen as well as milk yield, fat and the antioxidant status of the cows. The antioxidant defense mechanism of the animal is also dependent on other dietary nutrients. Dietarydeficiencies in Se, Cu, Zn, Mn and vitamin E contribute to oxidative stress by compromising the endogenousantioxidant enzymes and the immune response of the animal.
  11. 11. Oxidative Stress in Dairy Animals Feeding adequate (but not toxic) levels of traceminerals has been shown to benefit the health statusof the cattle by improving the immune response and antioxidant status, leading to better animal performance. However, not all trace minerals sources are equally available. Under dietary antagonisms, organic tracemineral have been shown to have higher bioavailability than the inorganic forms.
  12. 12. Oxidative Stress in Dairy Animals
  13. 13. Causes and Signs of Oxidative StressThere are many causes of oxidative stress:Metabolic stress (milk fever, ketosis etc.)Disease challenges (both bacterial and viral)Early 1st lactation, low or high body condition score can alsoelevate oxidative stress.Environmental conditions such as heat stress and social stressincreases oxidative stress.Vitamin and mineral imbalances can be linked to oxidativestress as well.Mycotoxins loads are among the most important feed-bornfactors contributing to oxidative stress and lipid peroxidation.•
  14. 14. Causes and Signs of Oxidative StressClinical signs can include:Lower dry matter intake and milk productionRetained placenta and other metabolic issuesUdder edemaMastitisDelayed first estrusDelayed first breedingRepeat breeding resulting from failure to conceive orfrom early embryonic death.
  15. 15. Nutrition and Oxidative Stress in Dairy AnimalsNutrition plays an important role in oxidative balance. Specific ingredients provide protection againstpathogen invasion or exposure. Certain nutrients also play a role in oxidative balance by increasing tissue integrity, strengthening the barrier to free-radical attack. A dairy cow’s nutrition program can help maintain oxidative balance. The nutrition program can benefitfrom the proper balance of antioxidants, minerals and amino acids
  16. 16. Nutrition and Oxidative Stress in Dairy AnimalsTalk to your nutritionist about:Commercially available antioxidant products whichmay fit into your herds program. This is particularlypertinent if you are feeding fat in your TMR.Make sure that the Vitamin E in your cows’ programsreflect current recommended standards. I balance for1000 KIU/head/day in the milking herd and 2000-4000KIU in the dry herd.Ensure that trace mineral nutrition in your herd isadequately addressed; I prefer chelated minerals.
  17. 17. Nutrition and Oxidative Stress in Dairy Animals Ensure amino acids are balanced in all of your herd’s programs. This is particularly true for methionine. Methionine can also be converted to the amino acid cysteine, which is used extensively by the immune system.
  18. 18. Nutrition and Oxidative Stress in Dairy AnimalsAt the barn level: Watch vitamins, mineral, amino acids in your herds’ nutrition. Reduce metabolic diseases in your herd with a comprehensive dry cow program. Vaccinate regularly Control heat stress Lower social stresses as much as possible with grouping strategies. Mycotoxins have no place in dairy nutrition, manage them accordingly. Body condition score regularly.