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The symposium 'Recent Advances in Animal Nutrition – Australia' (RA) was instigated at the University of New England (UNE) in the early 1970s. In the 1950s and 1960s, under the visionary leadership of Professor G. L. (Bill) McClymont, a talented group of young biochemists and nutritionists was recruited to become the Department of Biochemistry and Nutrition at UNE and quickly developed a strong reputation for nutritional research on ruminant and monogastric animals. Its members were keen to share their findings with relevant industry representatives and to learn about the major industry challenges. The idea for RA emerged ~1970 when Drs Robin Cumming and David Farrell saw the opportunity for regular RA schools, bringing invited experts from Australia or overseas to interact with UNE staff, post-graduate students and representatives of the monogastric and ruminant livestock industries. The first RA school was probably held in 1974. Aided by flexible working arrangements at UNE, David Farrell was able to champion further RA meetings that were held successfully about every 2 years. However, ~1990, the federal Education Minister John Dawkins began a process of amalgamating Australian higher-education institutions that produced detrimental administrative and financial ramifications for UNE and drained staff morale. After the 1993 meeting, Professor David Farrell left UNE, followed soon afterwards by Professor Ron Leng. The future of RA was at a crossroads; its funding and organisation needed overhauling to enable it to survive. A second, more formal phase of RA meetings (13 in all; 1995–2021), was instigated within a newly formed Department of Animal Science at UNE. The meetings became more formalised and even more financially dependent on industry support and sponsorship; meetings were planned by larger organising committees. Soon, papers were being formally refereed and the scope for provocative speculation of the type promoted at earlier meetings was somewhat curtailed in favour of scientific rigour. Organisers experimented with changed meeting dates, formats and venues at UNE, cumulating with a contentious decision to hold this meeting away from UNE. Despite its challenges, RA has grown in stature over 47 years from the small, informal schools of the early 1970s, to become Australia's leading animal nutrition symposium. 'Recent Advances in Animal Nutrition – Australia' has grown in stature over half a century to become Australia's leading nutrition symposium. This history describes how the first 'nutrition school' was conceived at the University of New England, Armidale (UNE), in the early 1970s, and covers the 25 biennial meetings held at UNE; it pays homage to the many organisers, invited speakers and attendees who have focussed on finding innovative solutions to industry-relevant problems, thereby ensuring the symposium's long-term success. [ABSTRACT FROM AUTHOR]

The effect of supplementing a mixed rice straw and tropical grass diet with legume as a nitrogen (N) source on intake, digestibility, rumen ammonia and microbial protein production was evaluated in Bos indicus cattle. Four rumen-cannulated steers were used in a crossover design with two diets and two periods. The diets were T1 = 40% rice (Oryza sativa L.) straw + 60% grass (Brachiaria spp. cv. Mulato II hybrid) and T2 = 40% rice straw + 30% grass + 30% legume (Stylosanthes guianensis cv. CIAT 184) on DM basis. Supplementation with legume doubled (P < 0.01) rice straw and total N intake, and increased total DM intake by 32%. It did not affect the DM, organic matter, neutral detergent fibre and acid detergent fibre digestibility (P > 0.05) but did increase (P < 0.05) N digestibility. Faecal N and total N outputs from T2 cattle were higher (P < 0.05) than T1 cattle, but urinary N output did not differ between diets (P > 0.05). N retention in T2 cattle was improved by 83% (P < 0.05) compared with T1 cattle. Rumen ammonia concentration, microbial protein production and efficiency of microbial protein production were improved (P < 0.05) when the legume forage was included in the straw-grass diet. We conclude that when a mixed rice straw and fresh grass diet is supplemented with ~30% legume (DM basis), significant improvements in DM and N intake can be achieved. Cattle nutrition in tropical areas depends on rice straw and tropical grass diet, which is insufficient in fermentable energy and protein. By supplementing ~30% legume (DM basic) to a mixed rice straw and grass diet, intake and microbial protein production were improved to achieve weight gaining of Bos indicus cattle. Using legume (Stylosanthes guianensis), as part of an eco-farming system, is a key solution for smallholder farmers to improve their cattle production. [ABSTRACT FROM AUTHOR]

Nitrate (NO3¯) is an effective non‐protein nitrogen source for gut microbes and reduces enteric methane (CH4) production in ruminants. Nitrate is reduced to ammonia by rumen bacteria with nitrite (NO2¯) produced as an intermediate. The absorption of NO2¯ can cause methaemoglobinaemia in ruminants. Metabolism of NO3¯ and NO2¯ in blood and animal tissues forms nitric oxide (NO) which has profound physiological effects in ruminants and has been shown to increase glucose uptake and insulin secretion in rodents and humans. We hypothesized that absorption of small quantities of NO2¯ resulting from a low‐risk dose of dietary NO3¯ will increase insulin sensitivity (SI) and glucose uptake in sheep. We evaluated the effect of feeding sheep with a diet supplemented with 18 g NO3¯/kg DM or urea (Ur) isonitrogenously to NO3¯, on insulin and glucose dynamics. A glucose tolerance test using an intravenous bolus of 1 ml/kg LW of 24% (w/v) glucose was conducted in twenty sheep, with 10 sheep receiving 1.8% supplementary NO3¯ and 10 receiving supplementary urea isonitrogenously to NO3¯. The MINMOD model used plasma glucose and insulin concentrations to estimate basal plasma insulin (Ib) and basal glucose concentration (Gb), insulin sensitivity (SI), glucose effectiveness (SG), acute insulin response (AIRg) and disposition index (DI). Nitrate supplementation had no effect on Ib (p > .05). The decrease in blood glucose occurred at the same rate in both dietary treatments (SG; p = .60), and there was no effect of NO3¯ on either Gb, SI, AIRg or DI. This experiment found that the insulin dynamics assessed using the MINMOD model were not affected by NO3¯ administered to fasted sheep at a low dose of 1.8% NO3¯ in the diet. [ABSTRACT FROM AUTHOR]

Abstract Long-term effects of dietary supplements on productivity, economics, and greenhouse gas (GHG) emissions of 2 beef enterprises were simulated, using AusBeef integrated with AusFarm®, across 30 years: Enterprise 1. Angus steers (1.5 head/ha) in New South Wales, Australia, grazing for 238 days/year, and Enterprise 2. British x Charolais steers (1.0 head/ha) in California, USA, grazing for 148 days/year. Simulation effects of 3 supplements with potential to reduce enteric methane (CH 4) emissions were evaluated: (1) nitrate (NO 3 ¯), (2) lipid, and (3) NO 3 ¯ + lipid. All supplementation effects were evaluated against a baseline simulation (i.e., no supplement). Results on beef production, rumen products, GHG emissions, and enterprise gross margins are reported. Simulations indicated that supplementing steers with lipid alone relative to the baseline in Enterprises 1 and 2: increased final live weight (LW) by 68 and 25 kg, decreased emissions intensity (EI) by 69 and 49 g CH 4 /kg live weight gain (LWG), and decreased total GHG by 0.08 and 0.04 t CO 2 -e/ha/year, respectively. Supplementing steers with NO 3 ¯ + lipid relative to the baseline: increased final LW by 70 and 30 kg, decreased EI by 89 and 77 g CH 4 /kg LWG, and decreased total GHG by 0.27 and 0.12 t CO 2 -e/ha/year for Enterprises 1 and 2 respectively. The most profitable mitigation strategy, across all years, for Enterprise 1 was the lipid supplement with a median gross margin of $AUD753/ha and for Enterprise 2 was the NO 3 ¯ + lipid supplement with a median gross margin of $AUD224/ha. The NO 3 ¯ supplement alone was the least preferred option across both enterprises, consistently delivering lower returns than other options across the entire probability range. The results indicate the potential economic benefit of lipid supplementation, either alone or in combination with NO 3 ¯, as GHG mitigation strategies that increase profitability and inhibit methanogenesis for beef production across diverse environments. [ABSTRACT FROM AUTHOR]