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HERD HEALTH IMPORTANT TO SUCCESSFUL BREEDING PROGRAM

Eric Grant and Wes Ishmael

Common sense tells you that herd health has a lot to do with the success or failure of a beef cattle breeding program. A preventative program can be set up with the help of your veterinarian.

Health programs should include a vaccination schedule along with regular deworming and treatments for grubs. It also should include an effective nutrition program, something we've already discussed.

Treatments for problems like scours, pink eye, grass tetany and pneumonia should be kept on hand as well as a stock of things like mild antiseptic solution, bandaging material, balling guns, syringes, a stomach pump and tube and a calf puller.

Ask your veterinarian for advice about the supplies you are likely to need. Your veterinarian should always be the first person you ask about all health-related topics and activities. Also ask for regular updates about new developments in preventative medicine.

Always call your veterinarian when a problem is beyond your level of experience or knowledge. Remember that treatment is most effective when an accurate diagnosis is made and appropriate measures are taken early.

In addition to vaccination and nutrition programs, your best herd health protection is experienced observation, accurate records and prompt response to abnormal situations. Guarding herd health also includes AI.

AI is your best defense against venereal and other diseases that can be spread via semen. Be sure you use semen from a reputable supplier, one that insures donor bull health tests (covering the semen collection period) are completed and negative, and that semen and semen extender are treated with appropriate quantities and types of antibiotics.

Don't make the mistake of assuming that semen is disease-free just because it's frozen and comes in neatly-sealed packages. When buying semen, check for the Certified Semen Services (CSS) logo. It's your proof that the AI organization supplying your semen is a participant in the industry's self-imposed program for disease control of semen for AI.

Moreover, your herd-health standards should account for other possible sources of infection, such as outside animals, whether they are females, clean-up bulls, or heat detectors. Be careful when introducing any animal into your herd, and con-sider using detector animals that cannot achieve sexual contact.

Advancements in herd health measures have decreased venereal diseases from a few years ago, but they are still a cause of reproductive failure. They can spread quickly through a herd and they don't give you any warning. You probably won't be aware that your herd is infected until your breeding records start to look strange - lots of irregular heats and lots of services but no calves. By then, you can bet the disease is thriving in your pastures.

CSS health requirements focus on six infectious diseases that are spread primarily through direct sexual contact or through infected semen. All six are not specifically venereal or exclusively genital but each is capable of reducing fertility. All six of these diseases can be avoided by using disease-free semen in an AI program.

Campylobacteriosis (formerly called vibriosis)

Bulls (or their semen) transfer campylobacteriosis, caused by bacteria, to a cow's genital tract causing a low-grade uterine infection. The embryo usually dies early and the cow returns to heat, although mid-term abortions can occur. Cows that fail to settle after several inseminations or cows that exhibit an irregular return to heat are evidence of campylobacteriosis.

Infected bulls can be treated successfully but they show no physical symptoms. Cows can be vaccinated, but your best protection is using disease-free semen in your AI program.

Trichomoniasis

Trichomoniasis, like campylo-bacteriosis, is passed during sexual contact or through contaminated semen and causes a low-grade infection in the uterus that results in temporary infertility. Rarely will an embryo large enough to be recognized be aborted. Once again, the only noticeable symptoms are irregular heats and repeated services.

Bulls with trichomoniasis will remain infected for life and there are no medications approved for use in food animals to treat infected bulls.

Although trichomoniasis cannot be treated in cows, it will run its course in a few months, and cows will then conceive and carry that calf to term. Even so, all cows should be considered infected until 90 days after that normal calving. For protection, inseminate with semen from infection-free bulls.

Leptospirosis

This bacterial disease exists in five significant types in the US. The organism responsible for leptospirosis initially infects and destroys red blood cells. Next the kidneys become infected, and the urine carries the bacteria and transmits the disease. Semen may become contaminated because both it and the urine pass through the urethra. If a cow is exposed to leptospirosis in pregnancy, she will abort during the last three months.

The cow herd should be vaccinated against leptospirosis, and you should use AI bulls that have been tested free of the organism.

Brucellosis (Bangs Disease)

Bangs is most commonly considered an abortion-causing disease of cows, but bulls may become genitally infected and spread the organism through their semen.

The bacteria that cause Bangs enter the buttons connecting the fetal membrane to the uterus, causing the nutrient supply to the fetus to be cut off and the fetus to be aborted, usually after the fifth month. Bacteria are present in the aborted embryos and in afterbirth of infected cows. After abortion, retained placentas and infertility problems occur.

Heifers can be vaccinated against Bangs. Because there is no cure, infected animals must be slaughtered.

Brucellosis is rarely transmitted through natural service, but when semen contaminated with brucella is placed through the cervix during AI, the transmission rate is quite high. Use disease-free semen.

Tuberculosis

Tuberculosis is usually considered to be a disease of the lungs and chest cavity, but bovine tuberculosis can infect the genitals and other organs. Contaminated semen can also spread the disease.

Tuberculosis is no longer common in the US, but because the disease can be difficult to diagnose and has a slow onset, only tuberculosis-free bulls should be used in an AI program.

Bovine Viral Diarrhea (BVD)

BVD is a viral disease with symptoms ranging from just a mild fever to more severe mucosal disease characterized by profuse diarrhea and subsequent death. Insemination with BVD virus-contaminated semen can also produce various reproductive disorders including repeat breeding and abortions.

If the fetus becomes infected with BVD during the first three months of pregnancy, and does not later abort, the resulting calf is often born with the BVD virus. Animals with persistent BVD infection do not mount an immune response and are therefore a major reservoir of virus. They are responsible for perpetuation of BVD in cattle herds from generation to generation.

Persistently infected bulls shed BVD in their semen, and transmission of BVD to the female through AI has been documented. Virus isolation techniques are being used successfully to detect persistent infection. It is imperative that bulls identified as persistently infected with BVD virus be eliminated from AI service. For your herd, you should establish a vaccination strategy coupled with the elimination of any persistently infected cattle and use of BVD virus negative AI bulls.

Much of the information in this article is based on information found in the Artificial Insemination Handbook, available in English, Spanish and Portuguese versions and is produced and distributed by the National Association of Animal Breeders. To order a copy of the handbook, contact NAAB at 573-445-4406.

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