No abstract

Batches (30-L) of first-milking bovine colostrum, inoculated with Mycoplasma bovis (10(8) cfu/mL), Listeria monocytogenes (10(6) cfu/mL), Escherichia coli O157:H7 (10(6) cfu/mL), Salmonella enteritidis (10(6) cfu/mL), and Mycobacterium avium subsp. paratuberculosis (Map; 10(3) cfu/mL), were heat-treated at 60 degrees C for 120 min in a commercial on-farm batch pasteurizer system. Duplicate 50-mL subsamples of colostrum were collected at 15-min intervals throughout the heat-treatment process for the purpose of bacterial culture and for measurement of IgG concentration (mg/mL) and antibody activity [log2(bovine viral diarrhea virus type 1 serum neutralization titer)]. Four replicate batches of colostrum were run for each of the 5 pathogens studied. There was no effect of heating moderate- to high-quality colostrum at 60 degrees C for at least 120 min on mean IgG concentration (pre = 60.5 mg/mL; post = 59.1 mg/mL). Similarly, there was no effect of heat-treatment on the mean log2 bovine viral diarrhea virus type 1 serum neutralization titer (pre = 12.3; post = 12.0). Viable M. bovis, L. monocytogenes, E. coli O157:H7, and S. enteritidis added to colostrum could not be detected after the colostrum was heat-treated at 60 degrees C for 30 min. Average bacteria counts showed that Map was not detected when batches were heated at 60 degrees C for 60 min. Although the authors believe that heat-treating colostrum at 60 degrees C for 60 min should be sufficient to eliminate Map from colostrum in most situations, further research is needed to determine whether these findings may be replicated, given that variability was observed in Map culture results.

Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.

The objectives were to describe the effect of on-farm commercial batch pasteurization on immunoglobulin (IgG) concentrations and the fluid and feeding characteristics of colostrum and to compare serum IgG concentrations in calves fed fresh versus pasteurized colostrum. Newborn calves (123) were systematically allocated to dietary treatments of either fresh or pasteurized colostrum at both the first and second colostrum feedings. The IgG concentrations were measured for batches of colostrum fed fresh and in pre and postpasteurized samples for batches of colostrum fed after being pasteurized and in calf serum. Pasteurization reduced colostrum IgG concentration, with the percentage reduction averaging 58.5 and 23.6% for 95-L and 57-L batches, respectively. Pasteurizing high quality colostrum in 57-L (vs. 95-L) batches resulted in higher IgG concentrations in the end product. Pasteurization of 57-L batches produced colostrum of normal or only mildly thickened consistency that could be fed to calves. Serum IgG concentrations were higher for calves fed fresh colostrum and for calves with a shorter time interval (< or = 6 h) between first and second colostrum feedings. After controlling for the time interval between feedings, serum IgG concentrations were significantly higher for 40 calves fed unpasteurized (19.1 mg/ml) vs. 55 calves fed pasteurized colostrum (9.7 mg/ml) for calves fed 2 L at first feeding. By contrast, there was no difference in serum IgG concentrations between 8 calves fed unpasteurized (16.1 mg/ml) and 20 calves fed pasteurized colostrum (13.5 mg/ml) after calves were fed 4 L at the first feeding. While the latter results suggest that pasteurizing colostrum may work for producers with excellent colostrum management, these results are preliminary and should be interpreted with caution, given the fewer number of calves and batches of colostrum involved with this second comparison.

The objective of this study was to identify the critical temperature, at or below which heat-treatment of bovine colostrum would produce no significant changes in viscosity, IgG concentration, or Ig activity. Results of preliminary work, using a Rapid Visco Analyzer (RVA) to heat 50-mL aliquots from 6 unique batches of bovine colostrum at 59, 60, 61, 62, and 63 degrees C, suggested that colostrum could be heated to 60 degrees C for up to 120 min without changing viscosity or IgG concentration. This finding was confirmed by heating 50-mL aliquots from 30 unique batches of colostrum in an RVA for 120 min at 60 and 63 degrees C. Heating colostrum to 63 degrees C resulted in an estimated 34% decrease in IgG concentration and 33% increase in viscosity. However, there was no difference in IgG concentration between preheat-treated (73.4 +/- 26.5 mg/mL) and post-heat-treated (74.5 +/- 24.3 mg/mL) samples after heating colostrum to 60 degrees C in an RVA for 120 min. Similarly, viscosity was unaffected after heating colostrum to 60 degrees C in an RVA for 120 min. High quality colostrum (> or =73.0 mg/mL) suffered greater losses of IgG and greater viscosity changes when heated to 63 degrees C than did moderate quality colostrum (<73.0 mg/mL). However, the effects of colostrum quality were minor if high quality colostrum was only heated to 60 degrees C. The results of a bovine viral diarrhea serum neutralization assay suggested that antibody activity was unchanged after heating colostrum to either 60 or 63 degrees C. However, these results were interpreted as being inconclusive due to a high proportion of missing results because of the congealing of many samples after heat treatment. The results of this study indicate that 50-mL volumes of bovine colostrum can be heat treated at 60 degrees C for up to 120 min in an RVA without affecting IgG concentration or viscosity.