When the RSPCA arrived at Ridgeway Farm, near
Purton, on August 5 last year, two of the flock were already dead and nearby railway workers said they had taken it upon themselves give water to some of the weaker lambs out of plastic bottles.
Two ewes and a lamb had to be euthanised immediately due to the severity of blowfly strike, as flies festered in open wounds.
Leigh Ballard, 21, admitted four charges at Swindon Magistrates Court, including causing unnecessary suffering and failing to ensure the welfare of his animals.
Ballard said he had left for Devon on August 1 in his capacity as a van driver and left his brother, Dennis, to care for the flock.