QPIF Rockhampton- based geneticist Dr Brian Burns discussed epigenetics - the unexpected results one gets when crossbreeding cattle that don't follow the norm.

For instance, if an Angus bull is joined to a Brahman female, the offspring will be smaller than the offspring from an Angus female joined to a Brahman bull, even though the genetics would be much the same.

That is because the Brahman female's maternal genetics override the male genetics of the sire and control the size of her calf.

The Brahman female is programmed to not waste resources.

So rather than putting energy into producing a big calf at the expense of her condition, she puts in only the minimum needed to ensure she produces a live calf and has the condition to feed it.

Lisgar runs Droughtmasters and they are being used to find out what effect fixed-time AI has on the economics of a herd.

That involves using hormones to synchronise the heat cycle of a group of cows so they can all be inseminated on the same day, about 60 days after calving.

One group of 23 mature cows was inseminated on January 4 and then the herd went back to natural mating.

It resulted in 58 percent of pregnancies due to AI and another 25 percent falling to the bull on the second heat.

All the AI calves were born over a three-week period starting October 7.

The breeding program is funded partly by Meat and Livestock Australia with commercial sponsorship from Bioniche Animal Health, a Canadian company which manufactures the hormone treatments that facilitate heat synchronisation.

Dr Gabrial Bo, the director of IRAC-BIOGEN Biotechnologias Reproductivss, Argentina, is the world's leading export on fixed-time AI and oversees projects across South America.

He told the audience the commercial industry had embraced the technology and in 2008 two million breeders underwent fixed-time AI in Brazil and 1.6 million in Argentina.