A comparative study of diagnostic tests for the assessment of herd magnesium status in cattle

Authors: Sutherland RJ, Bell KC, Carthew GW, McSporran KD
Publication: New Zealand Veterinary Journal, Volume 34, Issue 8, pp 133-135, Aug 1986
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Clinical pathology, Diagnostic procedures, Minerals/elememts, Metabolic disease, Disease/defect, Locomotor, Nervous system/neurology, Nutrition/metabolism
Article class: Scientific Article

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Abstract: In nine of ten pre-calving dairy herds we found that herd magnesium (Mg) status could be determined with 95% confidence by measurements of serum Mg (S-Mg), urinary Mg fractional clearance ratio (FCR) or creatinine corrected urinary Mg concentration (CUM) from 10 representative cows. Our findings support clinical impressions that FCR and CUM are more sensitive than S-Mg as predictors of a positive production response to Mg supplementation of dairy cows. The available clinical data is not adequately controlled and there is a need for controlled production-response trials to refine interpretation and to confirm the predictive value of these tests. Pending such trials we suggest that mean FCR >10% or CUM >1.0 mmoI/l indicate that a positive response is likely. In seven lactating herds the act of milking was not associated with depression of S-Mg and we conclude that sampling cows immediately after milking Gould not result in spurious elevations of FCR. FCR and CUM show close correlation with each other but not with S-Mg.

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