Mammalian and avian physiology, especially thermal physiology

2024 - : Extreme heat and pregnancy complications: harnessing the diverse Australian climate and population for global answers

Collaborators: C Wyrwoll (UWA), J Pillow (UWA), M Kearney (U Melb), and 15 others

Australia has a diverse climate and population. This context provides a unique opportunity to define the health implications of extreme heat exposure during pregnancy and extrapolate findings to a global context. This multidimensional proposal encompasses individual, population, and discovery science data. Three key aims encompass our proposal: 1) Lived Experience which includes Indigenous and recent migrant knowledge, 2) Environmental Epidemiology across the breadth of Australian climate zones, and 3) Biological Mechanisms utilising our established sheep model of pregnancy in environmentally controlled housing and human samples. These aims, along with community co-design and consultation, will lead to the development of approaches to minimise the adverse effects of extreme heat in pregnancy. The deliverables will include health education approaches for individuals and health care workers, identification of clinical applications for health management of pregnant patients in the heat, and development of new public health and policy approaches to preparedness, responsiveness, and secondary prevention for pregnant women in extreme heat. Key words: pregnancy, heatwave, physiology, epidemiology, at-risk populations.

Funded by The Wellcome Trust

 

 

2024 - : Intensification of northern cattle production in WA enabled by feed products from irrigated cropping

Collaborators: D Blache (UWA), C Revell (DPIRD), D Thomas (CSIRO), J Milton (UWA), L Ding (UWA)

Heat stress creates a limit on cattle productivity in tropical areas. With this project we will test the efficiency of using supplementation from the local cropping industry to finish cattle in feedlots. We will test the need for feed additives (minerals, vitamins, etc.) to optimise the use of that local feed source. Using a small-scale feedlot, we will test the suitability of three local sources of feed on young cattle to rapidly reach slaughter weight and maximize meat quality. Animals are equipped with an intra-ruminal temperature logger that records rumen temperature every five minutes to assess their heat balance and welfare. Meat quality will be assessed at slaughter and analysed by a team from Murdoch University.

Funded by The Cooperative Research Centre for Northern Agriculture

 

 

 

2023- : Design, establishment and benefits of edible shelter to improve lamb survival and whole-farm profitability

Collaborators: S Hancock (Murdoch), D Blache (UWA), H Norman (CSIRO), K Poole (UWA)

Shade and shelter may provide protection from cold and heat stress, a source of feed during prolonged or seasonal drought, specific essential nutrients, increased pasture and crop production, and improved landscape health. Cold stress contributes to the average of 8% (single) and 24% (twin) of lambs that die within three days of birth in Australia and the estimated 0.7% of the Australian flock that die post-shearing during extreme or unseasonal weather. Shelter has resulted in an average reduction in mortality of 18% for twin-born lambs and 7% for single-born lambs and decreases the susceptibility of ewes to metabolic disease and possibly dystocia. Because many of the published studies are from research areas where cold stress is expected, they are not indicative of industry-wide responses, this project will determine the probability of lamb and ewe deaths from cold stress across different sheep production areas. Although shelter may improve lamb survival, ewes do not always choose to lamb in a sheltered location. For this reason, there is a requirement for research into the voluntary use of shelter in commercial-sized paddocks and the role that nutritive value of shelter plays in attracting and holding ewes to shelter, and to their lambs.

Funded by Meat and Livestock Australia Donor Company

 

 

2022 - : Investigating heat stress in ewes – reproductive performance

Collaborators: D Blache (UWA), S Hancock (Murdoch), H Norman (CSIRO), K Poole (UWA)

Extreme thermal events represent a considerable biological challenge to animals. In sheep production, extreme heat events are known to affect development, growth, and reproduction. In the extensive pasture and pastoral based systems that are typical of Australia, sheep are exposed to a diverse range of extreme climatic conditions and have little to moderate access to shade. During the natural breeding period, cycling and pregnant ewes, as well as working rams, are often exposed to conditions that challenge their homeothermy, wellbeing, and reproductive function. The topology of a paddock, especially the presence of shade, can modify the level of exposure of individual sheep to a given heatwave intensity, and modify outcomes including reproductive rate. The frequency and amplitude of heatwaves has increased, and will increase further with climate change. The exposure of the Australian sheep flock to thermal stress will be more frequent and more intense in the future. The project aims to definitively, and more comprehensively, quantify the effects of heat events on sheep reproduction, thermoregulatory capacity, behaviour, and wellbeing through long term data collection during a range of climatic conditions in diverse production settings.

Funded by Meat and Livestock Australia Donor Company

 

 

2017- : Heat balance in humans – the effect of climate change on human activity

Collaborators: D Mitchell (Witwatersrand, S Africa), M Kearney (Melbourne)

While several health impacts of climate change have been widely reported, there has been limited discussion of how human physical activity will be impacted. We use empirical data on the upper limit of the prescriptive zone for humans to show that an index that is often used to assess human heat stress (the wet-bulb temperature) is a poor predictor of the prescriptive zone. We developed a different approach that was published in 2011, using rational heat balance modelling to incorporate every route of heat exchange and a newly developed rational model based on the nichemapper model for endotherms. That approach yields a much better prediction of the prescriptive zone. We use that model with global historical data, and climate projections, to assess the way that climate change will limit economic and leisure activity when conditions exceed the ability of humans to thermoregulate.

 

 

2014- : Scaling of the cardiovascular system in mammals

Collaborators: R Seymour (Adelaide), A Fuller (Witwatersrand, S Africa), E Snelling (Pretoria)

In vertebrate animals, the heart provides the work that propels blood to the lungs and the body, providing the exchange of oxygen and carbon dioxide that cells need to function. Given the role that the heart plays, the metabolic cost of the heart should vary with body size in the same fashion that metabolic rate of the whole animal does. But it doesn’t. It has become evident that the energetic cost of the circulation is not directly related to metabolic rate, neither in the same group nor between groups. By measuring heart work and aspects of the morphology of the heart and circulatory system, we aim to understand the factors that influence heart work in vertebrates of different sizes and different heart structure.

Funded by Australian Research Council

 

 

2014- : Circadian rhythms, health, and longevity

Collaborators: D Blache, G Goh, P Mark (UWA), Y Ootsuka (Flinders),

While the core body temperature of mammals and birds exhibits a circadian rhythm that is controlled by a master clock in the brain, it has become clear that the rhythm of body temperature can reset molecular clocks in peripheral tissues. Evidence is emerging that strong, robust circadian rhythms are associated with health, while disrupted or attenuated rhythms are indicative of disease. Using rodent and insect models, we manipulate the circadian pattern of core body temperature and measure variables including longevity and health related outcomes. The pharmacological manipulation of body temperature offers a promising route to alter, and is some cases remedy, cases where circadian rhythms are disrupted.

 

 

 

Unit coordination
SCIE5515 - Global Challenges in Biomedical Science
PHYL2002 - Cell Physiology

Teaching
PHYL3003 - Physiology of Nutrition and Metabolism
PHYL3004 - Physiology of Integrated Organ Function
ANHB3310/20 - Human Biology: Applications and Investigations

NEUR1001 - Neuroscience in Society

 

My field of research is comparative physiology. My research objective is to identify and explore the physiological mechanisms used by organisms (mainly mammals and birds) to adapt to environmental stressors. My principal area of focus is thermal physiology, particularly the regulation of brain temperature, and the consequences of strategies used by animals to maintain thermal homeostasis.

Because my curiosity is easily aroused in an interesting problem, our lab has collaborations in diverse areas. Recent examples are work in fields as diverse as giraffe hemodynamics, alpaca nutrition, and animal ethics and welfare. But the underlying theme is constant – a desire to understand how animals work (to borrow a term from Knut Schmidt-Nielsen).

Being diverse is hopefully an advantage as ‘integrative physiology’ (the word integrative is surely redundant) comes more into vogue. The generalists will have the big picture overview required to put results into whole-organism or whole-ecosystem paradigms. This lab aims to provide that capacity.
International linkages:
South Africa- University of the Witwatersrand: Prof. Duncan Mitchell, Prof. Andrea Fuller, Prof. David Gray. Ongoing collaboration since the 1990’s
USA- University of Wyoming: Prof. Graham Mitchell
Germany- University of Giessen: Prof. Claus Jessen (now retired)
Germany- Johann Wolfgang Goethe University: Prof. Elke Schleucher Research collaboration and co-supervision of students
Germany- Max Planck Institute for Ornithology: Germany Prof. Niels Rattenborg
Saudi Arabia- National Wildlife Research Centre: Prof. Mohammed Shobrak
National Collaborations:
Department of Primary Industries, NSW
Agriculture Department, Western Australia
LiveCorp, Meat and Livestock Australia
New South Wales Department of Environment and Climate Change (formerly National Parks and Wildlife Service)
Rio Tinto Ltd
University of Sydney
Murdoch University