In summer 2007, a randomized controlled field trial was initiated on 6 large Midwest commercial dairy farms to investigate the effect of feeding heat-treated (HT) colostrum on transmission of Mycobacterium avium ssp. paratuberculosis (MAP) and on future milk production and longevity within the herd. On each farm, colostrum was collected daily from fresh cows, pooled, divided into 2 aliquots, and then 1 aliquot was heat-treated in a commercial batch pasteurizer at 60°C for 60. min. A sample from each batch of colostrum was collected for PCR testing (MAP-positive vs. MAP-negative). Newborn heifer calves were removed from the dam within 30 to 60. min of birth and systematically assigned to be fed 3.8 L of either fresh (FR; n = 434) or heat-treated (HT; n = 490) colostrum within 2. h of birth. After reaching adulthood (>2 yr old), study animals were tested once annually for 3 yr (2010, 2011, 2012) for infection with MAP using serum ELISA and fecal culture. Lactation records describing milk production data and death or culling events were collected during the 3-yr testing period. Multivariable model logistic and linear regression was used to investigate the effect of feeding HT colostrum on risk for testing positive to MAP during the 3-yr testing period (positive/negative; logistic regression) and on first and second lactation milk yield (kg/cow; linear regression), respectively. Cox proportional hazards regression was used to investigate the effect of feeding HT colostrum on risk and time to removal from the herd. Fifteen percent of all study animals were fed PCR-positive colostrum. By the end of the 3-yr testing period, no difference was noted in the proportion of animals testing positive for MAP, with either serum ELISA or fecal culture, when comparing the HT group (10.5%) versus the FR group (8.1%). There was no effect of treatment on first- (HT = 11.797 kg; FR = 11,671. kg) or second-lactation (HT =. 11,013 kg; FR = 11,235 kg) milk production. The proportion of cows leaving the herd by study conclusion was not different for animals originally fed HT (68.0%) versus FR (71.7%) colostrum. Although a previous study showed that feeding HT colostrum (60°C for 60. min) produces short-term benefits, including improved passive transfer of IgG and reduced morbidity in the preweaning period, the current study found no benefit of feeding HT colostrum on long-term outcomes including risk for transmission of Mycobacterium avium ssp. paratuberculosis, milk production in the first and second lactation, and longevity within the herd.
Bibliographical noteFunding Information:
Phase I of this study (calf enrollment to weaning) was funded by USDA-Cooperative State Research, Education , and Extension Service (Washington, DC). This project was administered by Penn State University (University Park, PA) and the College of Veterinary Medicine, University of Minnesota. The authors thank the owners and managers of the 6 dairy herds for their participation and support. We also thank the many students who provided technical assistance throughout the study, including Eb Ballinger, Amber Hazel, Katie Konkol, Jennifer Belz, Amy Dahlke, and Maggie Wehseler (College of Veterinary Medicine, University of Minnesota. St. Paul).
- Heat treatment
- Johne's disease
- Mycobacterium avium ssp. paratuberculosis