The objective of this study was to determine the elimination kinetics of extended therapy with intramammary (IMM) cephapirin in lactating dairy cattle. Eight healthy Holstein-Friesian cows were administered cephapirin (200mg) into all 4 mammary glands every 24 h after milking. Cows were milked 3 times per day and concentrations of cephapirin and desacetyl cephapirin were determined in bucket milk using liquid chromatography-mass spectrometry. Milk concentration-time data after the last of the 8 IMM infusions were fitted using compartment and noncompartmental models. The maximum cephapirin concentration was 128±57 µg/mL (mean ± SD), the elimination rate constant from the central compartment was 0.278±0.046 (h(-1)), clearance was 0.053±0.023 L/h, the half time for elimination was 2.55±0.40 h, and the mean residence time was 2.65±0.79 h. The cephapirin concentration was below the approved tolerance in all cows by 96 h after the last infusion, which is the labeled withholding time for the preparation used. Extended therapy for 8 d provided milk cephapirin concentrations above the minimum inhibitory concentration for common gram-positive mastitis pathogens (0.1 to 1.0 µg/mL) for the duration of therapy and for an additional 16 to 32 h after the end of treatment. Our findings suggest that this IMM cephapirin sodium formulation, which is labeled for 2 doses 12 h apart, could be administered at a 24-h interval for up to 8 d in cows milked 3 times per day, with no significant effect on residue levels by 96 h after the last treatment. Longer withdrawal times would be prudent for cows with low milk production.
Ceftiofur, a time-dependent, bactericidal antibiotic active against bovine respiratory disease pathogens, is effective when the concentrations remain above the minimum inhibitory concentration (MIC) for at least 3-5 days. A new product, CCFA-SS, is a prolonged release formulation of ceftiofur, intended to provide single dose efficacy in cattle. It is administered subcutaneously (SC) in the ear, eliminating any injection in edible tissue. The objective of this study was to generate plasma ceftiofur concentration data following administration of CCFA-SS SC in the middle third of the posterior aspect of the ear.
Critical control points (CCPs) are the important thresholds that provide opportunities to measure the success of a process. The appropriate application of CCP in a heifer development program will provide insight as to the success or failure of management's efforts to introduce productive females into the herd. The first CCP occurs at breeding and reflects how appropriately the heifer's growth and phenotype have satisfied the physiologic demands of reproduction. Breeding management and breeding efficiency rates are examined at the second CCP, which is measured at the first pregnancy examination. The third CCP, measured at calving, gives an indication of the success of the nutritional plan and losses associated with pregnancy and the perinatal period. The fourth CCP, measured at the second season pregnancy exam, is a critical evaluation of how the heifer has fared with the cumulative stress of reproduction and lactation.
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