A ewe's body temperature can not only significantly impair her reproduction ability, but it can also impact upon her physiology, behaviour, and pregnancy.
This is according to a new trailblazing research underway at the University of Adelaide to measure heat stress in sheep, all carried out by remotely logging a sheep's temperature with the use of thermometry equipment.
PhD student from the University of Adelaide, Bobbie Lewis Baida, has developed the automatic devices to measure temperature in sheep, to better understand the impacts of body temperature on health and reproductive success.
Ms Lewis Baida, who was recently awarded the 2021 South Australian Research and Development Institute (SARDI) Science Bursary for Women, said although this is a vital area of research, it has not been thoroughly investigated in the past.
"The impact of heat stress in sheep in extensive grazing systems is not well understood," Ms Lewis Baida said.
"In a hot environment like South Australia, heat stress can affect sheep by threatening their physiology, reproductive function and overall health and productivity."
"Remote measurement of body temperature may be an efficient tool to prevent and manage heat stress in free-ranging sheep."
New evidence shows heat stress also posed a significant risk to the efficiency of the meat and wool production, with the impact increasing as global temperatures rise.
And according to Meat and Livestock Australia, the current national cost of heat stress is estimated to be between $97 - $168 million annually.
Remote measurement of body temperature may be an efficient tool to prevent and manage heat stress in free-ranging sheep
- Bobbie Lewis Baida
Ms Lewis Baida said the automated devices eliminate the need for human interference in data collection, which is crucial when working with sheep.
"Human presence disrupts the physiology of sheep and leads to stress-induced hyperthermia and increased metabolic heat production associated with the flight response," she said.
"When we plotted the temperatures of the ewes on a graph, you could see when we entered the animal house to collect their temperature, there was a spike in their vaginal temperature.
"It was collecting their temperature every 10 minutes, continuously, so you could see that our presence really influenced their body temperature."
She said studies that have previously looked at heat stress used manual rectal temperatures. They are now questioning whether it is measuring their core temperature or their stress response.
"It's a huge advantage to have this sort of technology, and especially in a research setting. You can put the loggers in and download all of the data," she said.
"You get a much more accurate insight into an animal's thermal status and can analyse their true response to heat whilst they are in the paddock."
Ms Lewis Baida is hoping the information gathered will determine the true impact of hot conditions, not only on sheep physiology and behaviour, but also on reproductive outcomes.
This coming summer she is planning to run a substantial sized trial adding in the component of gestation.
"When we artificial inseminate the ewes we will be able to look at a trans generational effect," Ms Lewis Baida said.
"We will be able to look at lamb growth and development, as well as birth weight of the lambs.
"It has been shown that with a high temperature status ewes produce lambs with a lower birth weight, but we really want to use this technology to get a more accurate data on that subject."
Ms Lewis Baida was recently named as the recipient of the SARDI Science Bursary for Women in 2021.
