Nutrition is the first defense
A healthy immune system is led by a balanced ration and planning for stress
Most beef herds are exposed to multiple health challenges. Viruses, bacteria, parasites and toxins can come from air, water, herd mates and wildlife. Stress factors such as weaning, co-mingling, handling, transportation and extreme temperatures exacerbate these challenges and can further suppress the immune system. Optimal nutrition is the first defensive measure. Optimal nutrition supports health functions and sends the animal toward its top genetic growth potential.
The immune system is composed of three general defense systems. The first two are called non-specific, in that typically the “defense” cells are indiscriminate against most foreign substances. First are skin and mucous secretions within the body. The second involves white blood cells from the blood stream and lymphoid tissues. These cells and sub-cells are released when there is injury to the body or by parasites and byproducts from allergic reactions. The cells seek and destroy harmful bacteria to prevent/fight against infection.
The third defense system is yet another set of white blood cells called T and B cells, but these are specific in nature. The primary function of these cells is to build specific ‘memory’ for the body against a particular invading virus. For example, giving a vaccine for BVD (Bovine Viral Diarrhea) is immunizing the body against invading BVD viruses. The T and B cells will act by producing specific antibodies that will bind to BVD only and will continue protecting against the organism.
It is a proficient and complex system. For it to work correctly the right nutrient profile for the animal is critical. All the basic nutrients have been shown to impact immune competence, including protein, energy, vitamins and minerals. For ruminants, by far the most important are protein and energy. Energy is the power source for the synthesis and function of immune cells, while protein regulates and provides structural element for cells and antibodies. During times of stress protein and energy are particularly important because stress can reduce intake, thus furthering the suppression of immunity functions through low intake of feedstuffs. When stress situations are impending, for example at weaning, supply a protein- and energy-dense feedstuff designed to compensate for low intake.
The roles of vitamins and minerals overlap for proper immune function. While there are several vitamins that are needed to support immune function, vitamins A and E need to be supplemented in the diet, whereas vitamins B6, B12 and C are supplied by rumen bugs and body tissues in sufficient levels. Multiple studies have demonstrated that vitamin E will increase the function of neutrophils (white blood cells), which are important scavengers of non-specific immunity.
Although several minerals are important for overall body function, zinc, copper and selenium are specifically important for the immune system and should always be offered to cattle in amounts that supply their requirements. Zinc is a well-studied trace mineral on immunity, particularly in stocker and feeder cattle. Zinc is essential in the formation of enzymes that work within cells thus making it vital for cell production, growth and function. A solid immune system is dependent on rapidly dividing cells and cell movement, therefore, a deficiency of zinc can have negative implications on animal health.
Negative interaction between trace minerals can also tie up availability of these nutrients.
University research recently found diets high in sulfur reduced retention of trace minerals copper, zinc and manganese in steers after only 20 days. Corn byproduct commodities, such as distillers grains and gluten feed, are high in sulfur. Thus, with diet high in these ingredients, consideration should be taken to insure there is adequate supplementation of the negatively affected elements.
Severe copper deficiency is generally due more to antagonistic effects of other minerals and/or organisms that make copper less bioavailable to the animal. Dietary molybdenum, sulfur and iron in excess can inhibit uptake of copper digestively, in tissues and bloodstream of ruminants. Consumption of heavy endophyte-
infected pasture starting mid-summer causes a reduction in overall intake, thus causing a deficiency of copper through simple lack of feed consumption.
During times of increased metabolic or immunological strain, overproduction of free radicals called reactive oxygen species (ROS) are formed as a normal end product. The over-accumulation of ROS can result in substantial damage to the animal’s tissues. Vitamin E and selenium are both highly effective antioxidants that will counter the effects of excessive ROS by preventing cellular dysfunction or premature protein degradation.
You should determination risk levels for your herd and plan for nutritional compensation during the most stressful periods. It will help you build an effective barrier against health challenges. The cash value of beef animals is at all-time highs. Along with those record prices, the return on supplementing the right nutrition to support your investment is at its peak.
Mark Epp is Ruminant nutritionist for MFA incorporated. Questions? Contact
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