Measurement of vitamin B12 in the livers and sera of sheep and cattle and an investigation of factors influencing serum vitamin B12 levels in sheep

Authors: Bond GC, Millar KR, Albyt AT
Publication: New Zealand Veterinary Journal, Volume 32, Issue 5, pp 65-70, May 1984
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant, Sheep
Subject Terms: Clinical pathology, Diagnostic procedures, Cobalt/vitamin B12, Trace elements, Liver/hepatic disease, Vitamins
Article class: Scientific Article

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Abstract: Modifications of a radioassay method for the analysis of vitamin B12 using chicken serum as the binder are described. This obviates the need to use individual serum blanks to correct for non-specific binding in vitamin B12 assays of the sera and livers of sheep and cattle. Samples with high vitamin B12 levels can be diluted prior to assay without loss of linearity. Recoveries of added cyanocobalamin or hydroxocobalamin were better than 95% and results correlated signiticantly with those obtained using a microbiological assay (Poteriochromonas malhamensis). Sera and liver samples stored for four weeks at temperatures ranging from -20° to 22° showed no change in vitamin B12 levels. Withholding food from sheep for 44 hours led to a marked increase in serum vitamin B12. This effect was also evident in sheep eating a limited amount of cut grass. In sheep at pasture there was no evidence of a diurnal variation in serum vitamin B12 levels. Serum vitamin B12 levels in sheep at pasture were shown to be an unreliable indicator of liver vitamin B12.

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