Claw trimming of dairy cattle

Low urea serum levels were detected in all six animals tested (range 1.6 to 2.23 mmol/l, mean 1.76 mmol/l, reference 3.4 to 7.3 mmol/l) but no other haematological and biochemical abnormalities were detected.No other predisposing causes were identified for this outbreak, which affected calves in pens with nose-to-nose contact, but also affected similarly aged calves kept in a pen two kilometres away that had been fed the same diet.There was some mould formation on the face of the grass silage clamp but this silage had been fed to the group of older calves on the same unit, which had not experienced any problems with tail biting.No ergot were seen within the silage.No mycotoxin testing of the silage was carried out; liver enzymes were normal, making hepatopathy unlikely.The cause of this outbreak of tailbiting is not immediately obvious.A dietary association causing pica seems likely, but older calves on the same unit were unaffected despite being fed the same silage.Low blood urea values suggested a deficiency of rumen degradable protein (RDP), although these animals were growing well.RDP deficiency can affect appetite in cattle.Another possible explanation for this outbreak is that one of the calves developed a behavioural abnormality for chewing tails, and the damage created attracted other calves to chew the tails of other calves and their own tails.However, this does not explain the virtually simultaneous outbreak in the group of calves kept two kilometres away that were fed the same diet (the only other link being the TB testing and staff moving between the two units).We would be interested to hear if practitioners have seen similar outbreaks of this seemingly rare condition (but which has serious welfare and financial implications) with the aim of further identifying risk factors.