Effect of Feeding Heat-Treated Colostrum on Preweaning Health, Economics and Transmission of Mycobacterium Avium Subsp. Paratuberculosis Inc

NON-TECHNICAL SUMMARY: Johne's disease is one of the most significant and costly infectious diseases affecting animal performance, animal welfare, profitability of the dairy herd enterprise and, quite possibly, public health. Disease in preweaned dairy calves is another important source of economic loss to dairy producers. But what do Johne's disease and calf hood disease have in common? One of the earliest potential exposures of dairy calves to infectious agents arrives with the first colostrum feeding. We need to develop colostrum management practices that could help to prevent pathogen transmission to newborn calves. The goal of this study is to perform a prospective controlled field study in commercial dairy herds to evaluate the effect of feeding heat-treated colostrum on preweaning health, economics, and Johne's disease transmission in dairy calves. The first objective of this study is to describe the efficacy and cost-benefit of feeding heat-treated bovine colostrum as a control point for reducing disease in preweaned dairy calves (Phase I). The second (long-term) objective of this study will be to describe the efficacy and cost-benefit of feeding heat-treated bovine colostrum as a critical control point for reducing transmission of Johne's to calves (Phase II). The long-term outcomes of this research will include the development of more scientifically and economically sound comprehensive Johne's control programs, improved animal health and well being, improved profitability and sustainability of commercial dairy farms, and improved food safety in the United States.

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APPROACH: Study Farms. This study will be completed in 8 to 10 commercial Holstein dairy herds in Minnesota and Wisconsin. Herds must be on a regular DHIA test program, have a history of clinical Johne's disease, and have had at least one fecal culture positive animal confirmed in the previous 3 years. One-time testing of 80 adult cows in their second or older lactation will be performed, using a pooled fecal culture method, to estimate the prevalence of Johne's infection in the herd. Colostrum Preparation. Unique batches of fresh colostrum (> 8 L per batch) will be well mixed and then split into two equal 4L duplicate aliquots. One of the 4 L aliquots will be selected for heat-treatment at 60 degrees C x 60 minutes in a commercial on-farm batch pasteurizer. For each batch, duplicate 50 ml samples of fresh (raw) and of heat-treated colostrum will be collected and frozen. Immediately after processing, fresh (3.8 L) and heat-treated (3.8 L) colostrum will be transferred into sanitized covered plastic feeding bottles, labeled, and refrigerated. Calf-Enrollment. Singleton newborn heifer calves will be removed from the dam by one hour of age and before suckling. Date of birth, dam ID, calf ID, gender and birth weight will be recorded. The calf will be systematically assigned to be fed 3.8 L of either fresh or heat-treated colostrum within 1-2 hours of birth. The colostrum bottle will be removed from the refrigerator, warmed to 95-105 degrees F in a warm water bath that is < 125 degrees F, mixed well, and then fed to the calf using the standard feeding method used by that farm. The colostrum batch number, date and treatment group will be recorded. After the first colostrum feeding, all calves will be housed separately and fed the standard milk feeding program that is in use on that farm. 1200 heifer calves (600/group) will be enrolled. Follow-up and Sampling During the Preweaning Period. Calves will be observed daily for illness and records will be kept of the calf ID, illness date, on-farm diagnosis (or veterinary diagnosis if available), treatments provided, and number of days treated. Death events will be recorded as calf ID, date, and on-farm diagnosis (or veterinary diagnosis if available). <p>Body weight (and date) will be recorded at time of weaning. A study technician will visit the farm once per week to collect a 10 ml blood sample from the jugular vein for each study calf between 24 hrs to 8 days of age. Laboratory Testing. Serum from blood samples will be split into equal aliquots, frozen, and then submitted for analysis of serum total protein (gm/dl) and serum immunoglobulin G (mg/ml) concentrations. Frozen duplicate paired (pre- and post-heat treatment) colostrum samples will be analyzed for colostrum IgG concentration (mg/ml) and bacteria counts. 20 ml of one colostrum sample from each batch will be tested for Mycobacterium avium subsp. paratuberculosis using a nested real-time PCR assay with a specific probe allowing for quantification.