Hypocalcaemia associated with high dose rates of zinc oxide to lactating dairy cows

Authors: Lawrence RJ, Towers NR, Smith BL, Collier AJ
Publication: New Zealand Veterinary Journal, Volume 32, Issue 4, pp 48-50, Apr 1984
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Biosecurity, Minerals/elememts, Inflammation, Integument/skin/wool/hair/fur/feather, Disease/defect, Disease control/eradication, Epidemiology, Mycotoxicosis, Liver/hepatic disease, Fungal/yeast, Metabolic disease, Locomotor, Nervous system/neurology, Photosensitivity, Toxicology, Treatment/therapy, Trace elements
Article class: Scientific Article

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Abstract: Clinical hypocalcaemia was associated with single doses of three oi more days` supply of zinc oxide to dairy cows for facial eczema control. Experimental hand dosing of a single dose of zinc oxide (40 and 120 mg Zn/kg b wt) to Jersey cows caused a significant drop in serum calcium concentration at 24 h followed by a rise to concentrations higher than controls at subsequent samplings over four days. At the highest zinc dose rate, 78% of serum calcium values were equal to or lower than the lowest control value at 24 h post dosing. Serum magnesium concentrations had a reciprocal relationship to the calcium levels at all samplings. Serum zinc concentrations were most elevated over the 48 h post dosing, returning to normal levels at the fifth day. Following the highest zinc dose milk yields were reduced by approximately 1.5 kg milk/cow/day for 48 h. Similar results were obtained when cows grazed pasture on which large amounts of zinc oxide had been sprayed.

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