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Basics Of Cattle Immunity

published: September 15th 2009
by: Tom Hairgrove, Steve Hammack

To formulate a vaccination program it is important to understand how animals naturally protect themselves from infection and how vaccines and other management factors enhance that protection.
    There are three major ways the body defends itself against infectious organisms.
    1. The first method is physical barriers, such as skin, normal microorganisms, and self cleaning procedures such as coughing, sneezing, vomiting and diarrhea. Organisms that penetrate the body are often eliminated by these procedures. It is important that animals be adequately hydrated and nourished for these barriers to work effectively.
    2. The second method of body defense is innate or native immunity. The native immune system controls invading organisms with chemicals and/or by ingesting them. The native immune system lacks memory and each infection is treated in the same manner. Adequate nutrition including energy, protein and minerals are required for maximal function of this system. Stress reduces the efficiency of the native immune system.
    3. The third method is the acquired immune system, which responds to vaccines. This system can recognize, and destroy specific invaders. Acquired immunity is unique in that it remembers the specific invaders and can mount a more intense response if stimulated by that specific invader later. While physical barriers and the native immune system are rapid in their response, the acquired immune system takes days to weeks to become effective. When the acquired immune system is compromised such as in human AIDS patients and cattle with bovine viral diarrhea (BVD), other diseases can rapidly overcome the animal defenses.
    Acquired immunity can involve specific antibody response (humoral immunity) or rapid recognition and destruction of specific foreign cells (cell mediated immunity). The humoral immune response is relatively easy to measure and the most common way immune responses to vaccine and/or disease are detected. Cell mediated response is much more difficult to quantify. The body responds to specific diseases with either an antibody or cell mediated response. Organisms that attack the outside of cells usually respond to antibodies. Organisms that invade the cell, such as all viruses and some bacteria such as brucellosis, often are better controlled with a cell mediated immune response.
    Modified live products are usually more efficient at protecting against diseases infecting the inside of the cell such as brucellosis or bovine viral diarrhea. Also, modified live products replicate in the animal and usually do not require a booster. However modified live products are very susceptible to being made ineffective if subjected to temperature extremes, light or chemicals. Killed products are usually more efficient at destroying organisms that attack the outside of the cell, such as blackleg or tetanus. Killed products do not replicate and usually require a booster to provide good protection. Killed products can give undesirable results if shaken excessively or frozen. All vaccines should be handled according to manufactures recommendations.
    Vaccination programs are only tools in a total health program. Adequate protein, energy and minerals are necessary to produce and properly dispatch various cells and antibodies required to give an adequate immune response. Environmental and social stressors as well as parasites can lower the animal's ability to immunologically respond to vaccine or disease. Administering too many vaccine products that are not compatible can lower immune response and cause other detrimental conditions in the animal. Some vaccines should not be administered to pregnant animals as they may cause reproductive loss. Vaccines are not always effective under field conditions. Producers should have reasonable expectations of vaccine programs; a vaccine program to prevent calves from becoming persistently infected with bovine viral diarrhea virus might be quite different from one to control bovine viral diarrhea in a group of stocker calves.
    You should consult with your veterinarian who is familiar with disease patterns in your area and is in the best position to recommend the most effective vaccination program.
    Livestock and Food animal systems Coordinator,- Professor Emeritus , Extension Beef Cattle Specialist.
References
    Tizzard IR, Veterinary Immunology an Introduction, 8th ed. Saunders Elsevier, 2009.
    Abul AK, Lichtman AH, Basic Immunology Functions and Disorders of the Immune System, 3rd ed. Sanders Elsevier, 2009.
    Roth JR, Basic Immunology and Principles of Vaccination, Institute for International Cooperation in Animal Biologics, May 2009.