Dr David Johnson has worked on a new cow body composition trait for Australian beef herds. Image Kim Woods
Cow body condition will become an important new trait for future proofing a beef cattle herd in southern Australia in a variable natural and political climate.
Animal Breeding and Genetics Unit principal scientist Dr David Johnston was a guest speaker at the Pasture Agronomy Service conference at Wagga Wagga on July 2, and outlined profit drivers within the control of the beef producer including cow size, feed intake, milk, reproduction and survival.
Dr Johnston spoke on the implications for profitability from a breeding perspective as agriculture faces variable rainfall, a hotter drier climate and the potential for a tax on methane emissions.
“This is a reality now – Denmark has announced a carbon tax of $145 per cow. What would that do to your profitability today if you were taxed $145 per cow? Making sure we address our production efficiencies in terms of age of turn off and reproduction is important before we measure one millilitre of methane,” he said.
Dr Johnston said the latest methane emissions research in cattle revealed low methane output was highly correlated to liveweight and feed intake.
“We can’t simply select for low methane as it will result in low feed intake and low growth rate. We need to know methane yield or which animal is producing less methane for the same feed intake.
“Breeding for low methane emissions is more of a social than a productivity issue. We can use genetics but also need to look at non-genetic options of improved pasture species, feed additives, cattle management, and culling of non-productive cows.
“In terms of a hotter, drier climate, we already have a production model in northern Australia using breeds with infused adaptation for tough conditions. We can use the power of crossbreeding or a combination of breeds in the future.
“If we have less feed or predictable feed in longer droughts and increased parasite burdens, what can we do within a breeding program to match the genetics to the environment by changing the balance of traits and might we need new traits?
“The availability and cost of feed will come to the fore with cow feed intake, her size and cow feed efficiency becoming more critical, stocking rate will be affected, cow survival (body condition) and male traits could be affected along with an increased parasite burden.
“Off-farm in a hotter, drier and more variable climate, the cost of feed will be more expensive, the age of slaughter will change and the ability to finish animals off grass, particularly if we want them to marble.
“The changing environment in our production systems will change the trait importance but critically it will change the relative importance between those two.”
The future emphasis of profit drivers for British breeds in southern Australia could be 60 per cent off-farm traits versus 40 per cent on farm, similar to the bos Indicus breeds.
Feed is the biggest input costs for a grower animal and the cow herd, with 65-85 per cent of energy requirements consumed by the cow herd. Effective selection will be based on cows eating less feed for the same weight gain to increase efficiency, rather than growth rate and cow size.
Dr Johnston said net feed intake is under moderate genetic control and can be changed by selection.
He said body condition score of most females was compromised as lactating first calf heifers losing liveweight, eye muscle area and fat.
Under development is a new Cow Body Composition estimated breeding value (EBV) for BREEDPLAN based on a one to five scale accounting for liveweight, hip height, scanned fat depth at rib and rump, and scanned eye muscle area.
“The EBV will identify those cows which crash after they have calved and bulls who will have daughters with a lower or higher body condition score going into mating.
“There is no relationship between the body composition EBVs for the daughters going into mating and the 400kg steer carcase rump fat EBV currently published.
“There is a mild relationship between body composition and BREEDPLAN milk EBV so milk will be in the picture in terms of why these cows are differing in their body composition.
“The Brahman breeders are seeing the cows with better body composition also having the genetics for higher marbling, so it seems to be associated with the partitioning of fat within these females during periods of peak energy requirement.
“The development of multibreed EBVs will also enable us to look across breeds to match the production system and genetics.”
Buffalo fly is a pest in the northern environment but have been steadily increasing their range southwards. This southerly range expansion is expected to accelerate as the climate warms.
“There are buffalo flies west of Armidale so we will need adaptation traits in our breeding objectives for parasitic burdens. Those flies cause lesions and secondary infection resulting in the animals being unsaleable for some markets.”
-Kim Woods