A property owner reported generalized loss of hair coat and greying of hair coat colouring affecting several amongst a group of mature Angus cows grazing high-production, kikuyu-clover based floodplain pastures. There had been three cases initially, but it appeared that more were starting to be affected. Cows were in fair to good body condition. Both dry and lactating cows appeared to be affected, but more lactating cows were affected than dry. Calves of affected cows also appeared somewhat under-grown and affected by scours. The herd had been periodically wormed with a macrocyclic lactone drench (not including younger calves), but not for at least six weeks before the property visit. There was no recent history of mineral supplementation, but 20%urea/salt/high sulphur blocks had been provided during the late winter period.
Approximately 10% of the herd were affected by hair loss and quite strikingly and obvious graying. An additional approximately 20% were showing some signs of hair loss and initial fading of coat colour.
Affected cows had lost most of their coarser guard hair, but retained the finer under-coat. Finer hair had changed colour from black to silver-grey. Visibly unaffected cattle had black coat colour with some, but not excessive (for the Grafton area), ginger-tip discolouration. Calves had some ginger-tip discolouration. Although cows were in fair body condition, affected cows appeared to be in lower condition than unaffected herd-mates and somewhat lower body condition than expected considering the quality and quantity of available pastures. Cows were strong, but worst affected individuals appeared to have somewhat pale ocular mucous membranes. A general observation was that faeces of affected cattle appeared somewhat loose relative to that of unaffected herd mates, but not so loose as to be gross scours. Vital signs of affected cattle were normal. Calves of affected cows appeared under-grown for age and all except one had somewhat watery scours. Calves also appeared to have pale mucous membranes.
Blood was collected from selected affected and visibly unaffected individuals for trace mineral analysis. Fresh faeces was collected for WECs. Tail hair root specimens were collected from ill-thrifty calves and one yearling for pestivirus antigen testing.
WECs were low to modest consistent with worming history.
Pestivirus antigen tests were all negative.
The table below summarizes trace mineral test results for eight selected cows from the herd, including four affected and four visibly unaffected individuals.
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Serum copper levels were universally low, but there was no obvious direct relationship between the serum copper level and the severity of coat discoloration or hair loss. This was obviously a major contributing factor for the condition amongst the cows and probably also the calf scours (calf serum was not collected for examination, however).
The literature mentions coat discoloration as an indicator of copper deficiency amongst cattle, particularly yellowing of red coat color and ginger-tip discoloration of black coat colour. To my knowledge, silver-grey discoloration of black coat color and the degree of hair loss observed in this herd have not been symptoms of copper deficiency noted in the literature, but there are anecdotal reports from the North Coast involving such coat colour changes associated with low blood copper and selenium levels in the past.
T4 levels were variable with some marginally low results. T4 results are difficult to interpret, but there did not appear to be any obvious predisposing factor for marginal low results (eg. internal parasitism) affecting the herd.
GSH PX levels were sound - perhaps somewhat surprising given the location, history and evidence of major copper deficiency. Selenium and copper are frequently deficient concurrently in the general area.
Vitamin B12 levels were very solid. The one high reading could be explained by minor faecal contamination of the specimen during tail collection of blood, but relatively high B12 levels are a common and relatively consistent finding in the Grafton area.