Our attention today hasn't been on cattle parasites but rather Foot and Mouth disease and BSE (Bovine Spongiform Encephalopathy). Yes, they are very serious but as of today neither have been reported in the United States. For that we should be thankful. However, there are numerous other diseases that affect cattle, many that confront us daily.

At this time of year, two very common problems are ectoparasites (lice and mites) and endoparasites ( those of the intestines, lungs, liver, kidneys, etc.). Recent research presented at the American Association of Veterinary Parasitologists documented a high prevalence of internal parasites in northern dairy herds.

A total of 1312 first- and second-calf heifers on 141 farms were included in a survey to determine the occurrence and types of internal parasites typically found in dairy herds in New York, Pennsylvania, Minnesota, and Wisconsin. Using fecal egg counts, investigators found that 77 percent (108) of the farms and 38 percent (492) of the cows had nematode eggs present. Ostertagia (brown stomach worm) was most prevalent in New York and Pennsylvania while Cooperia (small stomach worm) was most common in Minnesota. Haemonchus (barber's pole worm, large stomach worm or wire worm) was found most often in Wisconsin.

Considering management, 313 of the 674 animals raised on grass (46 percent) had positive fecal samples, and 133 of the 496 head raised in confinement (37 percent) were positive for internal parasites. Of the 84 farms that raised heifers on grass, 72 (86 percent) had positive fecal samples, while 33 of the 66 operations (50 percent) raising heifers in dry lots were positive. When grazing, especially if pastures are utilized yearly, with no interruption, contamination can become heavy.

Depending on severity, production, reproduction and feed efficiency, rate of gain and/or growth can be adversely affected. Recently, the USDA Immunology and Disease Research Laboratory in Beltsville, MD, reported that in addition to those mentioned, a reduction of the immune defenses has been noted. Louis Gasbarre, PhD, an immunologist at the USDA lab, says parasites, especially the brown stomach worm (Ostertagia) can cause immunosuppression which can reduce an animal's ability to respond to a vaccination.

Although the brown stomach worm causes the accelerated growth of some disease-fighting cells, Gasbarre explains, this action suppresses the growth of other immune cells that are also needed to fight disease. The resulting imbalance of immune cells can leave cattle unable to fight off infection or respond favorably to vaccines. In addition, secretions from the worms interfere with the animals natural immune response to parasite infection.

According to Gasbarre, because parasite infections hinder immune response, a vaccination program must be managed to maximize the vaccine's effectiveness. Ideally, vaccination should occur after parasite treatment, so the animals immune system can recover from the effects of the parasite infection. Dr. Gasbarre also states that the most effective waiting period has not yet been determined.

To further discuss this subject, consult with your veterinarian as to what steps to take, products to use, and the value of a systematic deworming program.

At this time, also be aware of lice and mites, primarily because of a heavy winter hair coat. Heavy lice infestation can lead to anemia, stunted growth and even death. Excellent products are available to combat lice and mites.

Treating for endo- and ectoparasites can give you, the owner, tremendous returns on your investment!

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