Numerous infectious diseases pose threats to producers

By MONETTE TAYLOR | South Central Texas Edition

January 22, 2004 -- Although producers and consumers are still reeling from the identification of a cow with Bovine Spongiform Encephalopathy (BSE), or "mad cow disease," in Washington State, a number of other infectious diseases seem more of a threat, according to Dr. Steven E. Wikse, DVM and Extension veterinarian at Texas A&M University.

Wikse addressed a "standing room only" crowd at the Corpus Christi Farm and Ranch Show held earlier in the month, explaining the various biosecurity practices he recommends to keep beef cattle herds safe and healthy.

While there are vaccines for various diseases, he said there is no one vaccine to prevent all problems, so producers need to be aware of two, major categories to keep herds safe and profitable.

First, Wikse discussed management practices that maintain a "high level of general resistance to infectious diseases," how to maintain a high level of "specific resistance against infectious diseases," and finally, how to minimize the spread of "infectious agents within the herd."

As for the general resistance to disease, he said proper nutrition that leads to a strong immune system in cattle is very important. He noted that in East and South Central Texas, selenium, copper and zinc are lacking in the soil, so those nutrients need to be addressed. Stress is another problem with cattle, and he advised avoiding crowding or mixing "first calvers and adults."

In order to maintain a high level of specific resistance to disease, he reminded producers they need to have a proper vaccination program for their herd, especially for bovine viral diarrhea (BVD) and Lepotospira borgpetersenii serovar hardjo (a kidney bacteria cattle can get from drinking out of irrigation ditches.)

As important as the first two recommendations to minimize exposure to infectious agents, Wikse impressed the necessity to isolate sick animals, bury the dead ones, not use the same equipment for feeding and manure-handling, and reduce wildlife reservoirs of Neosporosis.

When purchasing new animals, Wikse advised producers to buy only from herds with "high production levels" and good health programs, mentioning the Brucella Certification and the Texas Voluntary Johne's Disease Herd Status Program.

Although the BSE cow was found in Washington, Wikse said the United States has more testing and check points than are in place in other countries, and while Great Britain used rendered meat in 8 percent of their animals' feed, the United States used only 2 to 3 percent. Also, he mentioned Great Britain had a 25 percent rate in scrapies where as the United States was close to the 1 percent rate.

Wikse impressed the importance of de-worming cows and calves, relating the extra weight gain usually seen in weaning weights of calves that have been wormed, and said that May or June seem to be the best time for the worming.

A good feed program is very important, and Wikse said, "If you feed your cattle good, you have a big, strong 'firewall' to protect your herd."

He firmly recommended testing for the BVD virus, because it is very contagious, and Johne's Disease because of the high losses experienced in purebred herds who were infected.

Two other diseases he "highly" recommends testing ... especially for purebred herds ... are Neosporosis and Bovine Leukosis. According to records in the Ranch to Rail Calf Study, 60 percent of Texas beef herds (females) were infected with Neosporosis. While there is a vaccine, it has not been proven completely effective. The percentage of Texas beef herds infected with Bovine Leukosis has, also, been in the 60 percent range, and both sexes of animals need to be tested.

When purchasing a "non-virgin" bull, Wikse advised producers to be sure and test for Trichomoniasis in the bulls, because a presence of the disease can cause abortions in cows.

Wikse suggested testing for Salmonellosis, due to the diarrhea which can cause death and/or abortions and Leptospirosis which can cause the same, in addition to mastitis, although testing for these two diseases is more difficult.

Finally, he urged producers to be sure to quarantine newly-purchased animals for 60 days, after arrival, and not to allow "nose-to-nose" contact with the older herd members. While there are vaccines for some of the mentioned diseases, Wikse noted that alert management practices must accompany any vaccines to produce a successful beef cow/calf operation.

(Taylor is a reporter in Country World's South Central Texas office.)