Internal parasites, or gastro-intestinal worms, cost Australian cattle producers as much as $38 million a year in lost production and control according to Meat and Livestock Australia (MLA) figures.

Producers have traditionally relied on chemical drenches, but a project led by Dr Peter Honey and CSU professor of veterinary reproduction Peter Chenoweth is investigating the role of the host's genes.

"Aside from the cost of chemical controls, there are emerging problems with drench resistance and concern about residues and environmental contamination," Prof Chenoweth said.

"This project aims to show internal parasite resistance can be established in a herd using genetic selection without compromising profitability."

The researchers are working with Te Mania Angus and commercial beef producers from Team Te Mania, an Angus breeders group that has members across NSW, Victoria and South Australia.

Dr Honey said these producers were chosen because they had extensive pedigree records used to identify and rank bulls for economic traits.

"By the end of the project we will have sampled genetically linked weaner cattle across south-eastern Australia from Coolah in northern NSW to Narrung near the mouth of the Murray River," he said.

Samples are processed at the Veterinary Diagnostic Laboratory at CSU in Wagga Wagga and pedigree information is being used to identify bulls that have enhanced resistance to internal parasites.

"In one herd sampled, one bull had sired 22 percent of the weaner calves, but these calves produced only four percent of worm contamination on to pastures," Dr Honey said.

"These are the bulls we are looking for."

The final analysis of the genetic relationships is yet to be completed, but Prof Chenoweth is encouraged by initial results showing the trait of internal parasite resistance is up to 30pc heritable.