LIVESTOCK breeders have been warned there would be a cost to pushing for high productivity if they did not also pay attention to animal health and resilience traits.
At Meat & Livestock Australia’s Livestock Genetics Forum in Adelaide yesterday, senior CSIRO research scientist, animal measurement, Dr Brad Hine, said selecting for productivity is not selecting for resilience, “they are very different things.”
He warned producers that if they continued to push for high productivity and ignored health and fitness traits they would have highly productive animals “but they will not stay in the systems for very long because they just cannot cope with the challenges.”
Dr Hine advocated putting selection pressure on health and fitness, along with production traits, “and drag them both along together.”
The researcher leads several projects aimed at developing methodologies to assess immune competence phenotypes in sheep and cattle, working with genotyped and phenotyped industry reference flocks and beef herds, especially Angus Australia’s benchmarking progeny. About 5000 calves have been tested as a reference population to develop genomic predictions.
The research is trying to determine if there are variations in responses to disease challenges within populations, if immune competence traits heritable, what are the relationships between immune competence and other resilience traits – including temperament — and are there any associations with stress-coping ability and economically important traits. The long-term aim is to identify genetic markers associated with immune competence to develop a genetic prediction for the trait because it is difficult and expensive to measure.
He said immune competence is about general disease resistance, and the research is trying to identify animals that can cope with challenges under stress, including by measuring antibody and cell-mediated immune responses after vaccination.
What COVID can teach us about animal health
Dr Hine said there also were lots of learnings from the coronavirus pandemic that can be related to animal health.
Dr Hine said when a disease emerges, it can take time to generate a vaccine.
“So that’s a big learning.
“So I think part of the whole climate change story here and why I mention emerging diseases, is if we can build up the inherent resilience of animals – it’s not saying that we will make animals resistant to disease – but it might make them better able to cope with disease challenges that we don’t even know about yet,” he said.
“So just like we’ve seen with COVID, when COVID turns up you don’t get a vaccine tomorrow; it takes time.
“So vaccines are very effective, but strategies like improving the resilience of animals will help animals cope and improve (their) responses to vaccination,” he said.
“So if we could resilience test people and look at how they’ve responded to the COVID vaccine, it would be really interesting I think.”
Responses to vaccines vary
Dr Hine said a key message from the research is that when a producer vaccinates their animals, they don’t all respond similarly.
“Good news for us (researchers) that there is huge variation out there to work with, not such good news for livestock producers because there is an enormous variation in the ability of your animals to respond to a vaccine and that will relate to their ability to respond to a disease challenge.”
He said in beef cattle the heritability estimates for antibody-mediated responses is about 0.23 and for cell-mediated about 0.28.
“We’re continually updating these numbers, but heritability is moderate, that’s good news too, there is potential to select for this trait.
“What really interesting to us was that antibody and cell-mediated responses in beef cattle seem to be favourably genetically correlated, because that is not what we tends to see in dairy, but that again is good news.”
But he said generally the correlations between immune competence and a range of commonly measured production and other traits in Angus cattle are weak.
“So there were no really strong correlations that popped out.
Correlations with temperament, stress coping ability and other resilience-type traits were favourable, but they’re weak,” he said.
“Correlations with fat cover type traits were basically negligible and correlations with production traits were unfavourable, but weak.”
He said the production trait correlation is important but not unexpected.
“We knew when we started this work, based on what we’ve seen in other species that if you select for productivity alone, you will compromise an animal’s ability to cope with challenges.
“The good news, from what we see in Angus cattle, is that the correlation’s weak, it’s negative, but it’s weak, which tells us there will be animals in the population that are both highly resilient and very productive, we’ve just got to work out how to identify them.”
The cost of poor resilience
Dr Hine said research involving following feedlot steers through to finishing showed that the average direct cost from health-related issues of animals classified as low immune competence responders was $103.36 a head, whereas average responders cost $28.24 a head. The steers with a high immune competence cost only $3.53 per head after getting sick, but recovered to be productive.
“To me that’s what resilience is.”
Six percent of the low immune competence responders died at the feedlot, one percent of the average responders died and all of the high competence group survived.
“The really interesting thing is that 11.7 percent of the animals – those low immune competence animals – actually contributed to 35pc of the total health costs.
“My thinking is that if we can get those low responders out of the system, there is a lot of benefit there.”
Dr Hines said the immune competence work is not about replacing vaccines.
“This is about making those vaccines work better for you.
“So if you can get rid of the animals in your system that don’t respond to vaccination and aren’t protected, then that’s where the gain is.”
Resilience, antibiotics and social licence
Dr Hine said social licence to operate – maintaining consumer confidence — is an important issue for livestock producers worldwide.
He said Australia produced some of the best beef and lamb in the world and consumers want to buy the products knowing the animals have been raised in the environment they are happy with.
Dr Hine said consumers are demanding the highest standards of welfare for food animals and are concerned about agriculture’s contribution to the global issue of antimicrobial resistance.
Consumers also perceived antibiotic use as a threat, didn’t that antibiotics use could not discontinued without compromising animal welfare, he said. This needed to be addressed with new strategies and reducing antibiotic use while maintaining animal welfare.