Impact of bushfires on Australian livestock health, welfare and carcase quality.

The 2019/2020 Australian bushfires were unprecedented in terms of total area burned and impact on livestock and wildlife populations. However, there is currently limited literature available relating the consequences of bushfire or smoke exposure to livestock health, welfare, and carcase quality. A retrospective cross-sectional study was conducted using historical monitoring data from a Meat Standards Australia (MSA) accredited abattoir located on the mid-north coast of New South Wales, Australia. The spatiotemporal association between exposure to bushfire smoke (specifically the duration of the bushfires, distance from closest bushfire, annual bushfire season, proportion of the property of origin burned during the bushfires and time frame since exposure to bushfires) and effects on carcase meat quality metrics and pathology were measured, by building linear, generalised linear and cumulative link mixed models. Our findings indicate that hot carcase weight increased as the distance between the property of origin and the closest bushfire became greater and decreased with exposure to bushfires of longer duration or when greater proportions of the property of origin were burnt during bushfires. Subcutaneous rib fat of carcases also increased with an increasing distance of properties from the closest recorded bushfire and decreased with exposure to bushfires during the 2019/2020 season. Higher meat colour scores (darker meat colour) were associated with exposure to bushfires during the 2019/2020 season and exposure to bushfires of longer durations. There was only a weak association between increasing distance to the closest bushfire and higher marbling scores. Evidence of pneumonia in carcases was associated with exposure to bushfires of longer duration, specifically increasing risk of pneumonia was associated with fires of longer durations. Greater periods of time since exposure (i.e., >6 months) to bushfires were also associated with a higher risk of evidence of pneumonia at the time of processing. With increasing incidence of bushfires in Australia forecasted as a result of climate change, there is an urgent need to understand the impact of bushfires on livestock, to limit the effects on livestock health and mitigate the risk of significant socioeconomic impacts to the livestock industry. By providing a greater understanding of the impact of bushfires, the findings of this study can support producers to make informed decisions to mitigate the effects of bushfires on livestock health and carcase meat quality.

Exploring 'Wether' Grazing Patterns Differed in Native or Introduced Pastures in the Monaro Region of Australia.

Monitoring livestock allows insights to graziers on valuable information such as spatial distribution, foraging patterns, and animal behavior, which can significantly improve the management of livestock for optimal production. This study aimed to understand what potential variables are significant for predicting where sheep spent the most time in native (NP) and improved (IP) paddocks. Wethers (castrated male sheep) were tracked using Global Positioning System (GPS) collars on 15 sheep in the IP and 15 in the NP, respectively, on a property located in the Monaro region of Southern New South Wales, Australia. Trials were performed over four six-day periods in April, July, and November of 2014 and March in 2015. Data were analyzed to understand various trends that may have occurred during different seasons, using random forest models (RFMs). Of the factors investigated, Normalized Difference Vegetation Index (NDVI) was significant (p < 0.01) and highly important for wethers in the IP, but not the NP, suggesting that quality of pasture was key for wethers in the IP. Elevation, temperature, and near distance to trees were important and significant for predicting residency of wethers in the IP, as well as the NP. The result of this study highlights the ability of predictive models to provide insights on behavior-based modelling of GPS data and further enhance current knowledge about location-based choices of sheep on paddocks.

Disproportionate CH4 Sink Strength from an Endemic, Sub-Alpine Australian Soil Microbial Community.

Soil-to-atmosphere methane (CH4) fluxes are dependent on opposing microbial processes of production and consumption. Here we use a soil-vegetation gradient in an Australian sub-alpine ecosystem to examine links between composition of soil microbial communities, and the fluxes of greenhouse gases they regulate. For each soil/vegetation type (forest, grassland, and bog), we measured carbon dioxide (CO2) and CH4 fluxes and their production/consumption at 5 cm intervals to a depth of 30 cm. All soils were sources of CO2, ranging from 49 to 93 mg CO2 m-2 h-1. Forest soils were strong net sinks for CH4, at rates of up to -413 µg CH4 m-2 h-1. Grassland soils varied, with some soils acting as sources and some as sinks, but overall averaged -97 µg CH4 m-2 h-1. Bog soils were net sources of CH4 (+340 µg CH4 m-2 h-1). Methanotrophs were dominated by USCα in forest and grassland soils, and Candidatus Methylomirabilis in the bog soils. Methylocystis were also detected at relatively low abundance in all soils. Our study suggests that there is a disproportionately large contribution of these ecosystems to the global soil CH4 sink, which highlights our dependence on soil ecosystem services in remote locations driven by unique populations of soil microbes. It is paramount to explore and understand these remote, hard-to-reach ecosystems to better understand biogeochemical cycles that underpin global sustainability.

Phloem sap metabolites vary according to the interactive effects of nutrient supply and seasonal conditions in Eucalyptus globulus (Labill).

Improving the efficiency of fertilizer application is paramount to both the sustainability and profitability of forest plantations. Therefore, developing reliable, cost-effective tools to assess tree nutritional status is of great interest. This investigation sought to assess the use of phloem sap-derived metabolites as an indicator of nutritional status on a background of seasonal water availability of Eucalyptus globulus (Labill) trees grown under field conditions. Phloem is a central conduit for long-distance transport and signaling in plants and offers great promise in reflecting plant-scale resource limitations. Changes in the abundance of solutes and isotopes in phloem sap are sensitive to environmental cues. With a focus on both water and nutrient availability, we characterize patterns in phloem sugars, amino acids and the abundance of carbon isotopes in phloem sap obtained from E. globulus among different seasons and fertilizer treatments. Phloem-derived total amino acid concentration was found to increase with an increasing nitrogen (N) supply; however, this response was lost with the concurrent addition of phosphorus and at the highest level of N supply. Significant seasonal variation in all measured parameters was also detected, highlighting the need for caution in making quantitative relationships with growth. Broader implications of the interactive effects of both water supply and multi-nutrient additions and relationships with growth are discussed.

Mineral-Associated Soil Carbon is Resistant to Drought but Sensitive to Legumes and Microbial Biomass in an Australian Grassland.

Drought is predicted to increase in many areas of the world with consequences for soil carbon (C) dynamics. Plant litter, root exudates and microbial biomass can be used as C substrates to form organo-mineral complexes. Drought effects on plants and microbes could potentially compromise these relative stable soil C pools, by reducing plant C inputs and/or microbial activity. We conducted a 2-year drought experiment using rainout shelters in a semi-natural grassland. We measured aboveground biomass and C and nitrogen (N) in particulate organic matter (Pom), the organo-mineral fraction (Omin), and microbial biomass within the first 15 cm of soil. Aboveground plant biomass was reduced by 50% under drought in both years, but only the dominant C4 grasses were significantly affected. Soil C pools were not affected by drought, but were significantly higher in the relatively wet second year compared to the first year. Omin-C was positively related to microbial C during the first year, and positively related to clay and silt content in the second year. Increases in Omin-C in the second year were explained by increases in legume biomass and its effect on Pom-N and microbial biomass N (MBN) through structural equation modeling. In conclusion, soil C pools were unaffected by the drought treatment. Drought resistant legumes enhanced formation of organo-mineral complexes through increasing Pom-N and MBN. Our findings also indicate the importance of microbes for the formation of Omin-C as long as soil minerals have not reached their maximum capacity to bind with C (that is, saturation).

Effects of Topical Anaesthetic and Buccal Meloxicam Treatments on Concurrent Castration and Dehorning of Beef Calves.

The use of pain relief during castration and dehorning of calves on commercial beef operations can be limited by constraints associated with the delivery of analgesic agents. As topical anaesthetic (TA) and buccal meloxicam (MEL) are now available in Australia, offering practical analgesic treatments for concurrent castration and dehorning of beef calves, a study was conducted to determine their efficacy in providing pain relief when applied separately or in combination. Weaner calves were randomly allocated to; (1) no castration and dehorning/positive control (CONP); (2) castration and dehorning/negative control (CONN); (3) castration and dehorning with buccal meloxicam (BM); (4) castration and dehorning with topical anaesthetic (TA); and (5) castration and dehorning with buccal meloxicam and topical anaesthetic (BMTA). Weight gain, paddock utilisation, lying activity and individual behaviours following treatment were measured. CONP and BMTA calves had significantly greater weight gain than CONN calves (p < 0.001). CONN calves spent less time lying compared to BMTA calves on all days (p < 0.001). All dehorned and castrated calves spent more time walking (p = 0.024) and less time eating (p < 0.001) compared to CONP calves. There was a trend for CONP calves to spend the most time standing and CONN calves to spend the least time standing (p = 0.059). There were also trends for the frequency of head turns to be lowest in CONP and BMTA calves (p = 0.098) and tail flicks to be highest in CONN and BM calves (p = 0.061). The findings of this study suggest that TA and MEL can potentially improve welfare and production of calves following surgical castration and amputation dehorning.

Microbes as Engines of Ecosystem Function: When Does Community Structure Enhance Predictions of Ecosystem Processes?

Microorganisms are vital in mediating the earth's biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: 'When do we need to understand microbial community structure to accurately predict function?' We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but left 44% of variation unexplained on average, suggesting the potential for microbial data to increase model accuracy. Although only 29% of our datasets were significantly improved by adding information on microbial community structure, we observed improvement in models of processes mediated by narrow phylogenetic guilds via functional gene data, and conversely, improvement in models of facultative microbial processes via community diversity metrics. Our results also suggest that microbial diversity can strengthen predictions of respiration rates beyond microbial biomass parameters, as 53% of models were improved by incorporating both sets of predictors compared to 35% by microbial biomass alone. Our analysis represents the first comprehensive analysis of research examining links between microbial community structure and ecosystem function. Taken together, our results indicate that a greater understanding of microbial communities informed by ecological principles may enhance our ability to predict ecosystem process rates relative to assessments based on environmental variables and microbial physiology.