Technical information - Reproduction

Cow size improving female production


By by Lindel Greggery on behalf of ABBA

Conference Chairman Don Healy OAM is pictured with speakers Dr David Johnston who gave 2 presentations "The latest Brahman research to improve female and male reproduction" and "Innovations in incorporating genomics in genetic evaluations" and Dr Matt Wolcott who spoke on "Consequences of selection for cow size and body composition traits in Brahmans".

The Australian Brahman Breeders Association (ABBA) is taking a leading role in partnering with science to boost the profitability of beef herds through faster rates of genetic improvement.

Speaking at the World Brahman Congress Technical Conference in Rockhampton in May, Dr David Johnston, Principal Scientist, Animal Genetics and Breeding Unit (AGBU), University of New England, NSW said researchers were taking a four-pronged approach to improving both female and male reproduction traits in the Brahman breed.

This approach consists of evaluating new female reproduction traits, using male reproduction traits, taking novel molecular genetics approaches and increasing rates of adoption through the development of innovative application strategies.

"We need improved traits and better genetic evaluation, as there are lots of factors in improving reproduction rates," Dr Johnston said.

Dr Johnston said several research agencies were currently involved in different studies to assess female reproduction in tropical breeds. The research areas include ovarian scanning, assessment of lifetime reproductive performance, genetic evaluation, genomics and new recording technologies.

"We can improve female reproduction by one to two percent per year by selecting for key traits, it's not just nutrition," he told conference delegates.

AGBU scientist Dr Matt Wolcott shared with conference delegates the consequences of selecting for cow size and composition.

He said the Beef CRC's Northern Beef Productivity Project had conducted a 13-year progeny test using 1030 Brahman females supplied by six breeders. The females were evaluated for reproduction and body composition through up to six matings and their half sibling brothers were feedlot finished and slaughtered to measure carcase and meat quality.

Dr Wolcott said the study concluded that there was no genetic basis between how a cow looked in the paddock and her reproductive performance.

"In fact, animals that look in poor condition may be the most reproductively successful," he said.

These findings have important implications for studmasters who may have been inadvertently selecting females with poor reproductive performance, based on their phenotype.

He said Brahman stud breeders tended to retain cows that were in good condition and had larger calves at weaning. However the extra calf weight could be due to the cow missing a calf then dropping the next calf earlier.

"It's the classic example of a good intention going completely the wrong way. To make selection decisions in an informed way we have to measure the traits and can't just look at cow condition."

Dr Wolcott said recording birth dates and mating dates was a vital step for seedstock producers, to generate a Days to Calving EBV.

More sophisticated technologies such as ultrasound ovarian scanning are providing even more accurate assessments of lifetime reproduction by measuring days to puberty and lactation anoestrous interval.

"These traits are much more highly heritable than Days to Calving and have given us great power to make good genetic gains in reproductive performance in tropical breeds," he said.

While still a "work in progress" Dr Wolcott expects an EBV for Cow Condition will be added to tropical breeds' BREEDPLAN in the future.

Other findings from the long term study showed little genetic correlation between cow condition and the performance of steers in the feedlot.

This opens the door for multi-trait evaluations, meaning stud breeders could simultaneously improve female reproductive performance, cow weight and body condition, and steer growth, carcase and meat quality.

"Having good clear breeding objectives and recording in the best way that you can to meet these is the basics of any good selection program," Dr Wolcott said.

"By measuring the desired traits we can take our breeding program in whatever direction we want to go, and that is quite exciting."