Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 11, 2010
Publication Date: October 11, 2010
Citation: Ballou, M., Dailey, J.W., Hulbert, L.E., Cobb, C., Carroll, J.A. 2010. Effects of intravenous Escherichia coli (E. coli) dose on the pathophysiological response of colostrum-fed Jersey calves [abstract]. 2010 American Society of Animal Science Meeting, July 11-15, 2010, Denver, Colorado. Journal of Animal Science. 88(E-Supplement 2):M28. Technical Abstract: The objective was to determine the effects of E. coli dose on the pathophysiological response of dairy calves following an intravenous challenge. Eighteen 3-week old colostrum-fed Jersey calves were completely randomized to 1 of 6 doses of E. coli. The challenge doses included 0, 105, 106, 107, 108, and 109 colony-forming units (CFU) given as a bolus in 5 mL of sterile isotonic saline. Peripheral blood samples were collected at 0, 2, 4, 8, 12, 24, and 48h relative to the challenge for blood metabolite, total white blood cell count, and differential analyses. Rectal temperatures (RT) were collected via indwelling rectal probes at 1-min intervals, and hourly averages calculated from 2d prior to the challenge till 2d after the challenge. All calves survived the 48h observation period following the challenge. The behavior of calves given 10 exp 8 and 10 exp 9 CFU was altered (P < 0.01) beginning 0.5h after the challenge and returned to behavior similar to the control calves by 8 and 48h for calves challenged with 10 exp 8 and 10 exp 9 CFU, respectively. There were treatment x time interactions (P < 0.01) on total white blood cell counts and plasma glucose concentrations. Calves administered 10 exp 8 and 10 exp 9 CFU had leucopenia and neutropenia beginning 2h after the challenge and returning to counts similar to the control calves within 24h. Additionally, those calves were hypoglycemic from 4 to 12h after the challenge with the degree of hypoglycemia inversely related to the dose of E. coli. There were treatment x time interactions (P < 0.01) on RT following the challenge. All calves challenged with E. coli developed a febrile response, but the intensity and duration of the response were dependent on the challenge dose. These data indicate that calves challenged i.v. with 10 exp 8 and 10 exp 9 CFU of an E. coli showed immediate clinical and biochemical signs indicative of septicemia. However, calves administered 107 or less of the E. coli had febrile responses, but did not develop septicemia.