FROM CRC BEEF BULLETIN SPRING 2007

BRAHMAN NEWS DECEMBER 2007 Issue #157

The secrets of cow reproduction are being investigated by Beef CRC researchers, with the aim of bringing the power of genetic selection to bear on one of the major profit drivers in northern Australia’s beef industry.

Reproduction rate is a trait with low heritability. But research in Beef CRC Program 4: Female Reproductive Performance is looking to identify more heritable genetic attributes that collectively underpin “lifetime reproductive performance”, or the number of calves a cow can wean over six years.

Dr. Kishore Prayaga, senior research scientist, CSIRO Livestock Industries, said there is a strong argument that reproductive rate underpins the profitability of key northern beef enterprises, including the feedlot and live export sectors which depend on cattle numbers.

The Beef CRC has identified potential annual profitability improvements of $46.5 million from 2012 if the research is effective in delivering increased reproductive performance to northern beef producers.

The north, with 12.5 million head of cattle, represents 57 per cent of the Australian beef industry.

Northern Australia’s cattle industry has reproductive losses of between 5-10 percent in cows and 15-20 percent in heifers from pregnancy testing to weaning.

Reproductive losses are often connected with management – factors being investigated in Meat and Livestock Australia’s four-year Northern Australian Beef Fertility Project. But the Beef CRC Female Reproductive Performance program is looking at how genetic solutions might be brought to bear both on calf losses and conception rates.

Program 4 Manager, Jim Walkley, said the Beef CRC project has been built on top of the comprehensive data already collected by Beef CRC scientists on research herds in the north.

About 1900 cows at four research stations across Queensland, representing lines from generations already intensively recorded in Beef CRC II, are being assessed for mating and calving information, continuous measurement of body weight changes, teat and udder scores; measures of adaptability like resistance to parasites, heat and drought; and regularity of cycling.

“Ultimately, the aim is to have all the heritabilities and genetic relationships incorporated into Breedplan”

Dr Pragaya said the reproductive assessments – made every 4-5 weeks – would allow researchers to determine factors like days to cycling after calving, days to pregnancy after calving and days to calving after mating.

“The focus is primarily to understand the genetics of new traits and their relationships with all other traits measured, like age at puberty, age at first calving and calving history,” Dr Prayaga said.

Mr Walkley said other profitability issues, like growth rate and tropical adaptation, were recorded in Beef CRC II. But missing information related to lifetime reproductive performance will complete the picture.

“The information we accumulate in this new project will overlay the records we’ve already collected on these same females or their relatives, so we can associate lifetime reproduction traits with other production traits and uncover any linkages.”

“Ultimately, the aim is to have all the heritabilities and genetic relationships incorporated in BREEDPLAN, so cattle producers have a solid basis on which to base selection for reproduction along with other economically important traits like growth, adaptation and carcase quality.”

“As well, the project will provide an invaluable resource for discovery and validation of DNA markers associated with reproductive performance and adaptability to tropical environments,” he said.