RESEARCHERS from Western Sydney University’s Hawkesbury campus have discovered that summer heat waves impede animal reproduction.
The research was conducted by the team at Hawkesbury campus’ Stress Lab, and provided an insight into the broad ranging physiological effects of heatwaves on animals.
The study was conducted on Australian merino sheep during an artificial insemination program in Dubbo, and found that heat stress reduces embryo production.
Dr Edward Narayan from the School of Health and Science is the lead researcher and founder of the Stress Lab. Based at the Hawkesbury campus, the facility uses non-invasive techniques to measure physiological stress in wildlife and livestock.
Dr Narayan’s research has found that heat stress has a significant impact on the success of animal breeding programs.
Faecal samples and body temperature measurements were collected from 15 superovulating donor merino ewes during the 2015/16 summer, when ambient temperatures reached up to 39.9 degrees Celsius.
“Sheep production systems in the arid landscapes of regional Australia are frequently exposed to high ambient temperature or ‘heat waves’ during the summer period,” says Dr Narayan.
“Heat stress occurs when the environment acts to drive core body temperature above its normal range. This study sought to explain how key biological functions are affected by exposure to heat – and how heat stress may impact on reproductive function.”
The study found body temperature of the ewes to be a statistically significant factor for reduced embryo survival.
“In our study, ewes that had higher recorded temperatures had a significantly lower percentage of transferable embryos,” says Dr Narayan.
“It is assumed that elevated body temperature impedes certain reproductive processes that are crucial for embryo development. Heat stress is believed to reduce embryo production during the artificial insemination process, because the physiological and cellular aspects of reproductive function and early embryo development are disrupted.”
Dr Narayan says these results suggest a plausible link between heat stress, physiological stress and reduced fertility in merino ewes.
“Given that the Australian merino sheep industry is heavily reliant on the breeding efficacy of its ewes in order to maintain a profitable business – further research is required to determine the full extent that hot Australian climates could be impacting reproductive output.”
