Integrated BVD control plans for beef operations (Proceedings)
More than 60 years ago an enteric disease of cattle was described in North America that was characterized by outbreaks of diarrhea and erosive lesions of the digestive tract.17 The disease was called bovine viral diarrhea virus or BVD. The virus causing BVD was named bovine viral diarrhea virus (BVDV). Diseases in cattle resulting from infection with BVDV cause economic losses throughout the world. These economic losses are realized through decreased performance, loss of milk production, reproductive wastage, and increased risk of morbidity and mortality. Because of increasing realization of the serious impact that BVDV can have, efforts to control this virus have been steadily increasing. As we learn more about BVDV, there is also an increasing realization that successfully controlling BVDV requires a management program that involves multiple components and is customized to fit the goals and capabilities of each producer. By developing a complete program, the risk of BVDV associated losses can be significantly reduced.
Why Control BVDV –Importance
First, BVDV virus causes significant losses to the cattle industry. Second, we as an industry have excellent tools, some relatively new, to greatly improve control of BVDV. Third, by using planned approaches using these tools for BVDV control and working together as an industry we can utilize these tools to control this virus and thereby increase our ability to sustain cattle businesses and compete in domestic and foreign markets.Production and economic losses related to BVDV span all aspects of the beef and dairy industries in North America. From a beef herd perspective, costs of PI presence have been estimated to range from $14.85 to $24.84 USD per year per cow exposed to a bull in a published 10 year farm profitability model.11 A recent feedlot study in high risk cattle found fatality losses of $5.26 USD, performance losses of $88.26 USD and costs of PI exposure in feedlot cattle ranging from $41.84 to $93.52 USD per animal.8 Production and economic losses can be significant.8, 11, 24
Losses of productivity, including economic costs, extend throughout all phases of production in cattle enterprises. Pregnancy rates of cow herds with PI calves present have been measured at 5% lower than cow herds with no PI calves present.24 Immunosuppressive effects of the virus affect animals acutely diseased with the virus. This potentiates losses from secondary infections, including bovine respiratory disease, especially in feedlots, increased risk for neonatal calf diarrhea, and other infectious diseases of cattle.5, 14, 19 Control by individual operations at the cow/calf level can impact all sectors of beef production.
Cattle persistently infected with BVDV are defective individuals who adversely affect other cattle. Control strategies, especially prevention, reduces prevalence of PI animals in cattle populations, also decreasing their effects, costs and risks to individual animal owners as well as the industry as a whole. It is possible that large numbers of the cattle population become exposed during their lifetime even though PI animals are relatively rare.12 In a recent feedlot study, a 0.4% prevalence rate of PI calves resulted in exposure to 62% of the animals in the feedlot population.8 Some European countries are engaged in BVD eradication efforts. It is possible that international markets in the future may favor cattle from populations where BVD is eradicated.
Management decisions related to rising priority for BVD control can be made using program approaches that embrace biosecurity and biocontainment principles.22 Factors influencing selection of specific strategies include past BVD related losses, risk for future BVD related losses, risk tolerance and others.
Relatively new resources, including diagnostic tests, improved vaccines and better developed strategies for disease prevention are key for improved BVDV control, and even eradication, if chosen. Excellent tests utilizing IHC, ELISA and PCR technologies have become readily available to the industry.13 Vaccine development has focused on prevention of birth of PI calves and vaccines with data and labeling related to PI prevention (fetal protection) are available. Testing alone does not eliminate all risk for BVDV infection and vaccination alone will not prevent birth of all PI calves in the event exposure occurs. Therefore, it is critical that control strategies utilize these resources in a planned, systematic manner to achieve production and health related goals.