Robert Arthur Hunter

BAgrSc (Hons) (University of Queensland), PhD (University of Queensland)

Bob Hunter has an Agricultural Science degree with first class honours and a PhD from the University of Queensland. Bob’s whole professional career was with CSIRO, serving in Townsville, Perth and Rockhampton. The aim of much of Bob’s research was to increase annual liveweight gain of cattle in northern Australia mainly by reducing dry season weight loss. The focus was initially on the quantitative digestion of low-quality tropical grasses and on newly introduced tropical legume species. This research showed that in cattle, the rumen was even more important in the digestion of forages than it was with sheep. Studies then followed on the effects of supplementation with non-protein nitrogen, rumen degradable protein and rumen undegradable protein on rumen function and feed intake of low-quality forages with different digestion characteristics. In Rockhampton, the research was extended to include the effects of forage quality and protein supplementation on feed intake of cattle of different genotype, during pregnancy and lactation, and at different stages of maturity. While in Townsville, with Brian Siebert, a dual deficiency of sulphur and sodium was diagnosed and remedied in grass legume pastures on the western slopes of the Atherton Tableland. Supplementation with these elements is now routine husbandry in that area.

In the early 1980s, hormonal growth promotants (HGPs) were a new husbandry option in northern Australia, even though there was scant information about benefit where cattle took years, rather than months, to reach market weight. Bob was sent on study leave to the University of Nottingham where he worked with Professor Peter Buttery on the mechanism of action of HGPs. On his return to Rockhampton, research focussed on the metabolic regulation of liveweight gain and liveweight loss of cattle fed fibrous grass diets. Experiments that measured protein turnover and energy metabolism led to the discovery that trenbolone acetate was associated with a 10% reduction in maintenance energy requirements through a concomitant reduction in the rate of protein turnover. Associated with the reduced rate of protein degradation, there was a reduction in urea recycled to the rumen that caused a reduction in feed intake on protein-deficient diets. Trenbolone acetate was thus a useful agent for reducing the rate of dry season weight loss of non-breeding cattle provided the ruminal deficiency of nitrogen was overcome. The long periods of intermittent growth for steers to reach market weight was addressed by developing strategies for sustained growth promotion by sequential use of anabolic steroids with different mechanisms of action. These strategies had the spin-off effect of requiring less feed per unit of liveweight gain and had an environmental benefit as well provided the stocking rate was not increased.

Between postings in Townsville and Rockhampton, Bob spent 4 years in Perth where research centred on selenium supplementation to prevent the growth check or more seriously white muscle disease in growing lambs and weaners. It became obvious that not all intraruminal selenium pellets were giving the expected length of protection from deficiency. Bob initiated research with the CSIRO Division of Mineralogy and it was discovered that selenium was released into the rumen through a chemical reaction with the iron matrix. The smaller the grain size of the selenium and the larger the reactive surface the faster the reaction rate. With larger grain size selenium, the initial reactive surface was reduced and release occurred primarily by fissures of iron selenide migrating slowly through the selenium particles. Optimisation of grain size became a critical issue in manufacture of pellets.

Appointment as Officer-in-Charge of the Rendel Laboratory, Rockhampton, in 1993 commenced a period of research leadership and site management. Bob realised the importance of an appropriate balance between livestock production and environmental preservation. He established a small group of scientists who explored strategies for reduction in methane emissions from cattle. The group also undertook research, commissioned by a coal mining company, that defined the metabolic consequences of ingestion of high macro mineral loads in the drinking water. This research provided scientific evidence of the mineral loads that can be metabolically processed and eliminated from the body before productivity is compromised. This research is now captured in the Australian Water Quality Guidelines for Cattle. Bob was the Northern Deputy Director of the Cooperative Research Centre for the Cattle and Beef Industries (CRC) and played a significant role in sourcing a leased property for the herd of Brahman cows and their offspring that were central to the CRC genetics program in northern Australia.

Bob was active internationally presenting invited papers and conducting commissioned consultancies in S E Asia, Brazil and Papua New Guinea, USA and the UK. He led a decade-long ACIAR project that established a profitable beef industry on the infertile red soils of south central China. He is the author of 120 plus peer-reviewed journal papers, conference proceedings, invited book chapters and reviews. He served sequential terms on the editorial boards of the Australian Journal of Agricultural Research, Animal Production Science, and the Journal of Agricultural Science, Cambridge. He was also a long-term reviewer for the Swedish-based International Foundation for Science. He has been a member of the Australian Society of Animal Production since 1970 and was a regular presenter of papers at biennial conferences. He had executive positions on ASAP committees: secretary of the Western Australian Branch where he instigated a regular newsletter to members, and two separate terms as president of the Central Queensland Sub-branch. In each of these positions he organised producer-focused symposia on subjects of topical importance from which proceedings were published.

In recognition of his contribution to the livestock industries, especially in northern Australia, through research and leadership, and his unwavering support of ASAP/AAAS, the Australian Association of Animal Sciences is pleased to enrol Dr Bob Hunter as a Fellow.