Pig International - September 2017 - 22
22 ❙ PigInternational
Why protein requirements
differ for diseased livestock
Livestock have different nutritional requirements for protein when
challenged by disease, but we still lack sufficient information to
quantify these needs.
BY IOANNIS MAVROMICHALIS
Intensively farmed livestock are continuously exposed
to pathogenic organisms, resulting in the constant activation of their immune system. At best, this stimulates
their immune system, but the opposite is also possible.
In the latter case, this activation induces either a clinical or sub-clinical form of disease status that reduces
the biological and economic efficiency of protein accretion and daily weight gain. At the same time, this
inefficiency in protein accretion rate increases nutrient
excretion, especially that of nitrogen, which is now
considered an environmental pollutant.
Proper functioning of the immune system is absolutely critical to livestock survival and well-being.
The proper functioning of the immune system is
absolutely critical to livestock survival and well-being.
At the same time, the activation of the immune system
is also responsible for the reduction in carcass protein deposition, as clearly observed in sick livestock.
Provision of the correct nutrients, especially amino
acids, for the immune system can enhance its function
during times of stress while simultaneously minimizing detrimental effects on tissue growth.
In general, it is well documented that nutrition can
play a substantial role in disease prevention or alleviation of its symptoms. Nutritional supplements that prevent the establishment of diseases have long been used
in commercial practice. These include well-known compounds like zinc oxide, copper sulfate and antibiotics.
More recent nutritional strategies direct their efforts in
maximizing or supplementing the host immune system's
overall response. Examples include several yeast products and antibody-bearing ingredients such as hyper-immunized eggs. In addition, dietary nutrient manipulation
is considered essential in the face of disease because it
is now widely recognized that diseased livestock do not
have the same nutrient requirements as healthy ones.
This is most important in the case of amino acids.
Diseased livestock do not have the same nutrient
requirements as healthy ones.
Disease affects metabolism and requirements
Exposure to pathogenic antigens triggers the host
immune system and results in the release of pro-inﬂammatory cytokines (proteins that modulate the immune
response and overall metabolism). The most important
cytokines are interleukin-1 (IL-1), IL-6 and tumor necrosis factor alpha (TNF-α). Activation of the immune
system by these cytokines not only depresses appetite
but also reduces muscle protein synthesis and increases
muscle protein degradation (lower protein accretion
rate). At the same time, synthesis of acute phase proteins
in the liver are stimulated, leading to a totally different
Read more: Protein in pig diets: Meeting needs, avoiding excess,
www.WATTAgNet.com ❙ September 2017