Authorities have confirmed that 50 cattle that died in March at a Darwin export depot most likely succumbed to the intestinal disease cocciodiosis.
Another 100 head of cattle that were part of the same cohort perished while on board the Brahman Express live export vessel after it left Darwin on March 24 for Indonesia.
The depot deaths were dealt with by the NT government while the federal Department of Agriculture, Fisheries and Forestry, who were contacted for comment, are investigating the fatalities at sea.
Industry and DAFF had earlier said that clinical signs present in the cattle were consistent with botulism.
Northern Territory chief veterinarian officer Rob Williams said while it remained too early to "definitively rule out botulism", he told the ABC that the pathology collected by investigators now "strongly supports" coccidiosis, also know as weaning scours or black scours, as being the most likely cause of the 50 deaths.
It has been confirmed that all the deceased animals originated from the same central Australia property and had been at the export depot for around two weeks.
The facility remains temporarily suspended from processing cattle for export to Indonesia.
However, DAFF confirmed on March 29 that there was no evidence of exotic disease and Australia's Animal Health Status remains unchanged.
Dr Williams said the depot "followed their normal procedures and did the right thing."
"I think this was just an unfortunate event of cattle coming from a reasonably dry area to a wet area and the environmental conditions have contributed to this unusual [case]," he said.
"I don't think this was a management issue, this was more just unlucky... and probably a series of unfortunate events."
The Australian Livestock Exporters' Council said several weeks ago that all livestock loaded onto the vessel were assessed to be in good health and fit to load and were inspected by veterinarians prior to departure.
It also said the exporter had conducted itself correctly through the process and was working closely with DAFF to determine the cause of the deaths.
Coccidiosis is most common in young animals that have not yet developed immunity or resistance.
However, while the protozoal parasite coccidia normally lies dormant in the small and large intestinal walls of older animals there are several conditions under which a coccidian infestation can trigger coccidiosis disease.
The Meat and Livestock Australia website lists these triggers to include warm and wet areas, especially if stock density is high, animals confined to small areas, changes in environment and stressful conditions and feed or watering points contaminated with faeces.
It said that any of the triggers could suppress the animal's immune system enough to allow coccidia to multiply.
If a point of critical mass is then reached, according to a NT government fact sheet, the intestinal cells become damaged, causing "dark, foul smelling diarrhoea."
One of several key prevention tips listed by the MLA includes reducing faecal contamination of the environment.
