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What happens at the ranch can make a major difference in the feedyard, according to a Texas extension livestock specialist. A good herd immunity program by a cow/calf producer can yield dividends in the feedyard, an important point for cattlemen who retain ownership or who wish to build a reputation for quality cattle. While a herd immunity program costs money, there are times that if a producer spends more money, he can net more dollars. The ramifications of not spending money is loss of production. "It doesn't take many pregnancies to pay for a vaccination program," says Dr. Ron Gill, an extension livestock specialist in Dallas. The first step in establishing a program, he says, is knowing what kind of pathogens a producer might face and then planning a vaccination program to deal with them. The most common disease causing a problem in Texas cow herds is Leptospirosis. Lepto can be spread between cattle and wildlife, and it can be spread through drinking water and through animal contact. Lepto vaccines do not provide for more than six months of adequate immunity to vaccinated animals.
Respiratory Disease The pathogens involved in the Bovine Respiratory Disease (BRD) complex can cause problems in the reproductive performance of the breeding herd. By immunizing the cow herd, a producer can protect against reproductive losses and reduce death and sickness losses in the calf-crop resulting from viral infections. Several strains of bacteria are also components in BRD. "These bacteria are normally associated as secondary infections that occur after viral lesions are formed and immunity is impaired by one or more of the viral components," Gill said. "When death occurs due to respiratory disease, it is usually due to complications from bacterial infections." Bacteria most commonly associated with BRD are pasteurella hemolytica, pasteurella multocida and haemophilus somnus. "In calves, there can be losses simply due to bacterial infections," Gill said. "Calf pneumonia causes a fairly quick death in infected calves. Often calves will die within 48 hours of initial symptoms if not treated with antibiotics." Research indicates modified live vaccines are most effective in establishing herd immunity, however they are limited to use in non-pregnant cows, calves nursing non-pregnant cows and weaned calves. In other instances, a killed vaccine should be used. Another disease of concern to the breeding herd is haemophilus somnus which causes late term abortions. Control is possible with a vaccination program and sanitary management of the cow-herd. "Since these organisms are a problem primarily in weaned calves, it makes sense to include these in the vaccination program during the weaning and development phase," Gill said. Sexually Transmitted Disease The most common sexually transmitted diseases are campylobacteriosis, (more commonly referred to as vibriosis or vibrio) and trichomoniasis (trich). Vibrio is a bacterial infection that causes pregnancy losses in early gestation. The breeding herd should be vaccinated about 60 days prior to the onset of the breeding season. Trichomoniasis is an infection caused by a protozoa, and it is becoming more of a problem. It also causes early embryonic losses, but unlike vibrio there is normally a severe infection associated with trichomoniasis. The most effective way to avoid infecting the herd is to purchase bulls from a known origin and quarantine all incoming cows. Brucellosis is another disease that has plagued the industry although the brucellosis eradication program is close to showing long awaited results. However, it is still wise to vaccinate heifers against brucellosis before they reach 10 months of age, preferably, between three and six months old. Heifers over a year old are not vaccinated against brucellosis. A licensed veterinarian must administer the vaccine. |
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