IMMUNOLOGY AND INTERVENTION STRATEGIES FOR JOHNE'S DISEASE
Location: Infectious Bacterial Diseases Research Unit
Title: Heat-treated colostrum and reduced morbidity in preweaned dairy calves: results of a randomized trial and examination of mechanisms of effectiveness
| Godden, S - |
| Smolenski, D - |
| Donahue, M - |
| Oakes, J - |
| Bey, R - |
| Wells, S - |
| Sreevatsan, S - |
| Fetrow, J - |
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2012
Publication Date: June 20, 2012
Citation: Godden, S.M., Smolenski, D.J., Donahue, M., Oakes, J.M., Bey, R., Wells, S., Sreevatsan, S., Stabel, J.R., Fetrow, J. 2012. Heat-treated colostrum and reduced morbidity in preweaned dairy calves: Results of a randomized trial and examination of mechanisms of effectiveness. Journal of Dairy Science. 95:4029-4040.
Interpretive Summary: Morbidity and mortality in neonatal calves is a major concern for dairy producers. Evidence suggests that calves can become infected shortly after birth by exposure to pathogens such as Mycobacterium avium subsp. paratuberculosis, Salmonella, and Mycoplasma in either the feces or milk of infected dams, bedding or cohabitation with other infected animals. These pathogens may be spread to calves through colostrum from sick or infected cows. Some producers have opted to feed colostrums replacers to their calves to avoid the potential spread of disease. However, this is an additional expense that some producers cannot afford. Pasteurization of colostrum is an economical alternative to commercial colostrums products, however, little is known about its effectiveness in reducing morbidity in young calves. In the present study, calves fed heat-treated colostrum had significantly higher serum IgG concentrations and were at significantly lower risk for treatment for scours and for treatment for illness (any cause) in the preweaning period, as compared to calves fed fresh colostrum. Analysis suggested that calves fed heat-treated colostrum were at lower risk for illness because the heat-treatment process caused a significant reduction in colostrum total coliform counts, which was associated with a reduced risk for illness as a function of improved serum IgG concentrations.
A randomized controlled clinical trial was conducted using 1071 newborn calves from six commercial dairy farms in Minnesota and Wisconsin, with the primary objective being to describe the effects of feeding heat-treated colostrum on serum immunoglobulin G concentration and health in the preweaning period. A secondary objective was to complete a path analysis to identify intermediate factors that may explain how feeding heat-treated colostrum reduced risk for illness. On each farm colostrum was collected each day, pooled, divided into two aliquots, and then one aliquot was heat-treated in a commercial batch pasteurizer at 60ºC for 60 minutes. Samples of pre- and post- heat-treated colostrum were collected for standard microbial culture (total plate count, total coliform count, cfu/ml) and testing for immunoglobulin G concentrations (mg/ml). Newborn calves were removed from the dam, generally within 30-60 minutes of birth, and systematically assigned to be fed 3.8 L of either fresh (FR, n = 518) or heat-treated colostrum (HT, n = 553) within 2 hours of birth. Venous blood samples were collected from calves between 1-7 days of age for measurement serum IgG concentrations (mg/ml). All treatment and mortality events were recorded by farm staff between birth and weaning. Mixed linear regression found that serum IgG concentrations were significantly higher in calves fed HT colostrum (18.0 ± 1.5 mg/ml) as compared to calves fed FR colostrum (15.4 ± 1.5 mg/ml). Survival analysis using Cox proportional hazards regression found that there was a significant increase in risk for a treatment event (any cause) in calves fed FR colostrum (36.5%, H.R.Fresh = 1.25) as compared to calves fed HT colostrum (30.9%). Also there was a significant increase in risk for treatment for scours in calves fed FR colostrum (20.7%, H.R.Fresh = 1.32) as compared to calves fed HT colostrum (16.5%). Path analysis suggested that calves fed HT colostrum were at lower risk for illness because the heat-treatment process caused a significant reduction in colostrum TCC, which was associated with a reduced risk for illness as a function of improved serum IgG concentrations.