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.

1. Oxidative Stress in Dairy Cows

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. 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 antioxidant
capacity 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. What is Oxidative Stress?

5. What is Oxidative Stress?
In situations where the levels of free radicals exceed
the antioxidant capacity of the animal, oxidative stress
occurs. High-producing dairy cows are prone to
oxidative stress, and the situation can be exacerbated
under 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. 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 animal
in 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 understand
the need for proper balance and the role that nutrition
plays.

7. What is Oxidative Stress?

8. What is Oxidative Stress?
A cow with a large amount of oxidation occurring will
have 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. Oxidative Stress in Dairy Animals
Dietary 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. Oxidative Stress in Dairy Animals
In dairy cattle, commercially available dietary
antioxidants have been shown to improve fiber
digestibility 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. Dietary
deficiencies in Se, Cu, Zn, Mn and vitamin E contribute
to oxidative stress by compromising the endogenous
antioxidant enzymes and the immune response of the
animal.

11. Oxidative Stress in Dairy Animals
Feeding adequate (but not toxic) levels of trace
minerals has been shown to benefit the health status
of 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 trace
mineral have been shown to have higher bioavailability
than the inorganic forms.

12. Oxidative Stress in Dairy Animals

13. Causes and Signs of Oxidative Stress
There 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 also
elevate oxidative stress.
Environmental conditions such as heat stress and social stress
increases oxidative stress.
Vitamin and mineral imbalances can be linked to oxidative
stress as well.
Mycotoxins loads are among the most important feed-born
factors contributing to oxidative stress and lipid peroxidation.
•

14. Causes and Signs of Oxidative Stress
Clinical 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 or
from early embryonic death.

15. Nutrition and Oxidative Stress in Dairy Animals
Nutrition plays an important role in oxidative balance.
Specific ingredients provide protection against
pathogen 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 benefit
from the proper balance of antioxidants, minerals and
amino acids

16. Nutrition and Oxidative Stress in Dairy Animals
Talk to your nutritionist about:
Commercially available antioxidant products which
may fit into your herds program. This is particularly
pertinent if you are feeding fat in your TMR.
Make sure that the Vitamin E in your cows’ programs
reflect current recommended standards. I balance for
1000 KIU/head/day in the milking herd and 2000-4000
KIU in the dry herd.
Ensure that trace mineral nutrition in your herd is
adequately addressed; I prefer chelated minerals.

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. Nutrition and Oxidative Stress in Dairy Animals
At 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.