Research to understand the different physiological responses of beef cattle to stress events could improve resilience, leading to breeding healthier farm animals with higher productivity.
Animals in production environments face a range of challenges or ‘stress’ events including climatic extremes and disease challenges. Some animals seem to have a natural resilience for coping well with these events.
CSIRO research in collaboration with partners and Meat Livestock Australia (MLA) are investigating what characteristics contribute to increased natural resilience and research to date has already indicated accelerated animal recovery and productivity to pre-stress levels.
Coping with heat stress
When exposed to hot weather, feedlot cattle will eat less while losing 20 per cent of their energy intake to the body’s maintenance systems. The resulting reduced production in Australian feedlots over summer has been estimated to cost around $16.5 million.
Much has been done by industry and MLA to improve welfare and productivity of feedlot cattle during summer and safeguard them against the most extreme effects of heat waves.
However, there are still many gaps in our knowledge of how cattle respond to heat stress. Initial data from the first year of a five year research project studying cattle in climate control chambers and field pen trials are already providing interesting results.
Project co-leaders, Dr Gene Wijffels from CSIRO and Dr John Gaughan from the University of Queensland, are confident that the project will shed light on the complex responses that take place in the animal, involving hormonal, metabolic and inflammatory changes that can potentially cause gut damage.
“So far, we have found that the climate chambers don’t reflect the real world adequately and consequently we will be focussing on the pen trials over the coming years,” Dr Wijffels said.
Over the last two summers and winter, we have been monitoring 80 head of cattle in at the University of Queensland research feedlot (Gatton). Besides monitoring rumen temperature, respiration and weight gain, blood was collected every week. This is a lot of data but initial results confirm that as the temperature changes, we see a corresponding change in blood cells. There are also major seasonal changes to major blood biochemistry.
“We are linking these changes in blood cells to markers for inflammatory responses and loss of gut integrity and looking at how quickly the cattle recover to pre-stress levels.”
“As more data comes in, we can start to test what type of strategies, such as specific speed additives or other interventions, may protect the gut against damage and help speed up recovery after heat stress,” she said.
Response to disease stress
To understand the capacity of beef cattle to respond to disease challenges, we must first establish a set of meaningful measurements that can assess ‘general immune competence’ of individual animals.
This MLA co-funded project lead by CSIRO’s Mr Aaron Ingham, is currently developing on-farm testing procedures to assess the immune competence of beef cattle, an important component of an animal’s resilience.
“We will combine immune competence traits with measures of temperament and ability to cope with management induced stress to estimate an animal’s resilience,” Mr Ingham said.
The types of testing we are conducting include measures of 1) cell-mediated immunity using a skin reaction test, 2) antibody-mediated immunity using a test to determine antibody production in blood 3) temperament using ‘flight speed’ when exiting the crush and 4) ability to cope with stressful events by testing stress-induced production of markers in blood.
“By exploring associations between resilience and important production traits we aim to develop breeding strategies which will identify animals highly suited to their production environment,” he said.
As our research progresses and our understanding of production animal response to stress improves, our ability to select for highly resilient traits will result in healthier animals able to recover to high productivity levels.
Image credit CSIRO
First published in Leading Agriculture Issue 7