A Tasmanian court has heard that a malnourished flock of sheep was too weak to repel attacks from crows.
Farmer Philip Colin Osborne is facing charges after dozens of sheep were found dead or dying his northern midlands property.
He has pleaded not guilty to three charges, including one count of animal cruelty.
Animal nutritionist Colin Jessup told the Magistrates Court in Launceston he visited Osborne's farm over two days in June 2011.
He found dozens of very thin sheep, 40 wiener merino sheep were dead and another 40 had to be put down.
Some weighed less than half the normal body weight.
Mr Jessup told the court the sheep had very little pasture and the hay had low nutritional value.
They had been recently shorn and some had bloodstains on their wool where they had been too weak to defend themselves from crow attacks.
Mr Jessup said 150 sheep died on the the farm in the winter before his visit.
The hearing is expected to last for two days.