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Dean T. Thomas
CSIRO Agriculture and Food, Floreat Laboratory, Private Bag 5, Wembley, WA 6913, Australia

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Feed

Research article
Published: 01 January 2021 in Animal Production Science
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Context Modern crop stubbles provide an important source of feed for sheep during summer but can vary widely in their feeding value due to Genetics × Environment × Management interactions during crop growth, and how chaff is managed at harvest. Stubbles are difficult to assess for grazing value, due to the heterogeneity of forage components (e.g. stem, leaf, grains), which means that livestock producers rely on their observations and experience to manage sheep grazing stubbles. Aims To provide current information on the feeding value of stubbles, and to establish better methods for estimating stubble feeding value. Methods In the present paper, we report the results of sheep grazing wheat-stubble paddocks and a survey of the nutritive value of standing stubbles and chaff lines and piles of grain crops (including wheat, barley, canola and lupins) from crop paddocks in the mixed-farming region of Western Australia. Key results Without supplementation, wheat stubbles provided 50–100 dry sheep equivalent grazing days per hectare, before the estimated metabolisable energy (ME) intake of sheep fell below maintenance. This was influenced by ewe body condition score, where sheep of lower body condition gained more weight on stubbles (89 g/day higher weight gain per unit lower body condition score). Estimated ME content of edible chaff (leaf, fine stem and seed sheath or pod, excluding main stem and grain) was 5% higher in barley, 19% higher in lupin, and 5% lower in canola, than in wheat chaff, which was 5.9 MJ ME/kg DM. Implications While the grazing value of modern stubbles is variable, they have an important role in the seasonal feedbase by providing several months of feed during summer. Chaff by itself does not meet the energy or protein requirements of livestock, so a high-protein grain supplement (e.g. lupins) is necessary to maintain non-lactating ewes fed only chaff. The increased use of chaff lines and piles at harvest, primarily for weed control, provides a new opportunity to fill feed gaps in sheep and cattle enterprises if the material can be transported and stored efficiently, or if grazed in situ, as is common practice.

ACS Style

Dean T. Thomas; Andrew F. Toovey; Elizabeth Hulm; Gonzalo Mata. The value of stubbles and chaff from grain crops as a source of summer feed for sheep. Animal Production Science 2021, 61, 256 .

AMA Style

Dean T. Thomas, Andrew F. Toovey, Elizabeth Hulm, Gonzalo Mata. The value of stubbles and chaff from grain crops as a source of summer feed for sheep. Animal Production Science. 2021; 61 (3):256.

Chicago/Turabian Style

Dean T. Thomas; Andrew F. Toovey; Elizabeth Hulm; Gonzalo Mata. 2021. "The value of stubbles and chaff from grain crops as a source of summer feed for sheep." Animal Production Science 61, no. 3: 256.

Review
Published: 16 December 2019 in Sustainability
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Managed temperate grasslands occupy 25% of the world, which is 70% of global agricultural land. These lands are an important source of food for the global population. This review paper examines the impacts of climate change on managed temperate grasslands and grassland-based livestock and effectiveness of adaptation and mitigation options and their interactions. The paper clarifies that moderately elevated atmospheric CO2 (eCO2) enhances photosynthesis, however it may be restiricted by variations in rainfall and temperature, shifts in plant’s growing seasons, and nutrient availability. Different responses of plant functional types and their photosynthetic pathways to the combined effects of climatic change may result in compositional changes in plant communities, while more research is required to clarify the specific responses. We have also considered how other interacting factors, such as a progressive nitrogen limitation (PNL) of soils under eCO2, may affect interactions of the animal and the environment and the associated production. In addition to observed and modelled declines in grasslands productivity, changes in forage quality are expected. The health and productivity of grassland-based livestock are expected to decline through direct and indirect effects from climate change. Livestock enterprises are also significant cause of increased global greenhouse gas (GHG) emissions (about 14.5%), so climate risk-management is partly to develop and apply effective mitigation measures. Overall, our finding indicates complex impact that will vary by region, with more negative than positive impacts. This means that both wins and losses for grassland managers can be expected in different circumstances, thus the analysis of climate change impact required with potential adaptations and mitigation strategies to be developed at local and regional levels.

ACS Style

Afshin Ghahramani; S. Mark Howden; Agustin Del Prado; Dean T. Thomas; Andrew D. Moore; Boyu Ji; Serkan Ates. Climate Change Impact, Adaptation, and Mitigation in Temperate Grazing Systems: A Review. Sustainability 2019, 11, 7224 .

AMA Style

Afshin Ghahramani, S. Mark Howden, Agustin Del Prado, Dean T. Thomas, Andrew D. Moore, Boyu Ji, Serkan Ates. Climate Change Impact, Adaptation, and Mitigation in Temperate Grazing Systems: A Review. Sustainability. 2019; 11 (24):7224.

Chicago/Turabian Style

Afshin Ghahramani; S. Mark Howden; Agustin Del Prado; Dean T. Thomas; Andrew D. Moore; Boyu Ji; Serkan Ates. 2019. "Climate Change Impact, Adaptation, and Mitigation in Temperate Grazing Systems: A Review." Sustainability 11, no. 24: 7224.

Journal article
Published: 01 May 2018 in Agricultural Systems
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Maintaining the productive capacity of the agricultural soils of Australia's broadacre cropping zone requires careful management, given a highly variable climate and soils that are susceptible to degradation. Mixed crop-livestock farming systems are the predominant land use across these regions and managers must operate farms for long-term sustainability as well as shorter-term profitability. Achieving profitable and sustainable businesses has required ongoing innovation and productivity gains, of which the integration of crop and livestock enterprises has been an important part. Production-soil erosion trade-offs associated with enterprise integration is critical information that has not been investigated to date at a whole-farm level. The objective of this study was to systematically evaluate management options developed in Grain and Graze (an integrated program of research, development and extension targeting mixed farms) to identify farm systems responses to soil erosion risks across seven regions spanning the mixed-farming area of Australia. To evaluate production-soil erosion trade-offs, we linked the APSIM soil water, soil nutrient cycling, annual crop and surface residue simulation models to the GRAZPLAN pasture and ruminant simulation models, using the AusFarm modelling software. Our results demonstrate that the management options tested in Grain and Graze support the principles of conservation agriculture and inform the sustainable intensification of mixed farming systems. Across the regions considered we found that: (1) Increasing pasture legume content and soil fertility can consistently benefit farm production and environmental indicators, (2) management interventions that target direct management of ground cover have the greatest potential to reduce soil erosion rates, (3) management during critical periods of naturally high soil erodibility and wind/water erosivity can substantially increase or decrease erosion risk; the timing of management interventions is therefore critical, and (4) grazing management to balance use of crop residues and pasture biomass is required to avoid developing hot spots of erosion and soil degradation.

ACS Style

Dean T. Thomas; Andrew D. Moore; Lindsay W. Bell; Nicholas Webb. Ground cover, erosion risk and production implications of targeted management practices in Australian mixed farming systems: Lessons from the Grain and Graze program. Agricultural Systems 2018, 162, 123 -135.

AMA Style

Dean T. Thomas, Andrew D. Moore, Lindsay W. Bell, Nicholas Webb. Ground cover, erosion risk and production implications of targeted management practices in Australian mixed farming systems: Lessons from the Grain and Graze program. Agricultural Systems. 2018; 162 ():123-135.

Chicago/Turabian Style

Dean T. Thomas; Andrew D. Moore; Lindsay W. Bell; Nicholas Webb. 2018. "Ground cover, erosion risk and production implications of targeted management practices in Australian mixed farming systems: Lessons from the Grain and Graze program." Agricultural Systems 162, no. : 123-135.

Journal article
Published: 01 January 2018 in Remote Sensing of Environment
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ACS Style

Adrian Chappell; Nicholas Webb; Juan Guerschman; Dean T. Thomas; Gonzalo Mata; Rebecca Handcock; John F. Leys; Harry J. Butler. Improving ground cover monitoring for wind erosion assessment using MODIS BRDF parameters. Remote Sensing of Environment 2018, 204, 756 -768.

AMA Style

Adrian Chappell, Nicholas Webb, Juan Guerschman, Dean T. Thomas, Gonzalo Mata, Rebecca Handcock, John F. Leys, Harry J. Butler. Improving ground cover monitoring for wind erosion assessment using MODIS BRDF parameters. Remote Sensing of Environment. 2018; 204 ():756-768.

Chicago/Turabian Style

Adrian Chappell; Nicholas Webb; Juan Guerschman; Dean T. Thomas; Gonzalo Mata; Rebecca Handcock; John F. Leys; Harry J. Butler. 2018. "Improving ground cover monitoring for wind erosion assessment using MODIS BRDF parameters." Remote Sensing of Environment 204, no. : 756-768.

Research article
Published: 01 January 2017 in Animal Production Science
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Grazing immature cereal crops, particularly different varieties of wheat, has become widely adopted in the high rainfall areas of southern Australia. Recently, there has been growing interest in applying this technology in drier parts of the mixed farming zones of Western Australia. A modelling study was conducted to examine farm business returns with or without the grazing of immature wheat (winter and spring varieties) in different locations of Western Australia (Merredin, Wickepin and Kojonup), representing the low to high rainfall (319–528 mm) cropping regions, respectively. A combination of APSIM (crop simulation model) and GrassGro (pasture and livestock simulation model), were used to evaluate the changes in farm gross margins with the grazing of cereal crops at three locations of Western Australia. The results of the study showed that grazing the two wheat varieties (dual-purpose winter and spring) at the high rainfall location increased the profitability of the livestock enterprise by 2.5 times more than grazing crops at both low rainfall locations (P < 0.05). Across all years and sites, the average supplementary feeding costs were reduced by the inclusion of grazed winter (12%) and spring (2%) wheat crops in the lamb production system. The comparative reduction in the cost of supplementary feeding varied between locations and by crop variety within locations, due to both the frequency and average duration of the grazing of wheat crops in these regions, and the farm-stocking rate that was chosen. Both wheat varieties were grazed frequently at the lowest rainfall site (68% and 30% of years for winter and spring wheat varieties respectively), whereas grazing spring wheat was less frequent at the higher rainfall location and averaged 16% of years due to a greater difference in the relative availability of wheat crops versus pasture for grazing among regions. The grazing model assumed that there were abundant productive mixed ryegrass and subterranean clover pasture in the farming system. Overall, this study suggests that both winter and spring wheat crops are likely to supply green feed during the winter feed shortage (April–July) and reduce supplementary feed requirements for a short period of time in some seasons. The value of grazing crops is likely to be higher on farms with poorer soils and less productive pastures.

ACS Style

E. Hussein; D. T. Thomas; L. W. Bell; Dominique Blache. Grazing winter and spring wheat crops improves the profitability of prime lamb production in mixed farming systems of Western Australia. Animal Production Science 2017, 57, 2082 -2090.

AMA Style

E. Hussein, D. T. Thomas, L. W. Bell, Dominique Blache. Grazing winter and spring wheat crops improves the profitability of prime lamb production in mixed farming systems of Western Australia. Animal Production Science. 2017; 57 (10):2082-2090.

Chicago/Turabian Style

E. Hussein; D. T. Thomas; L. W. Bell; Dominique Blache. 2017. "Grazing winter and spring wheat crops improves the profitability of prime lamb production in mixed farming systems of Western Australia." Animal Production Science 57, no. 10: 2082-2090.

Research article
Published: 01 January 2015 in Crop and Pasture Science
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Grazing sheep on cereal crops in winter has become widely adopted in medium–high-rainfall zones of Australia. Interest in this practice has spread to the lower rainfall parts of the cereal–livestock zone where it is being applied to shorter season crop varieties. A farm-system modelling study was conducted to investigate the value of deferment of annual pastures by grazing spring wheat in their place. The biophysical simulation model, based on a representative wheat and sheep farming system in the wheatbelt of Western Australia, involved two grazing-management scenarios and used climate data for the period 1962–2011 for three locations in Western Australia representing low-, medium- and high-rainfall cropping regions: Merredin, Wickepin and Kojonup. The grazing-management policy of the main scenario, ‘crop grazing’, placed livestock on the crops only until the crop reached Zadoks growth stage 30, provided the green biomass of the farm’s annual pastures was

ACS Style

Dean T. Thomas; Andrew D. Moore; Hayley C. Norman; Clinton K. Revell. Small effects of deferment of annual pastures through grazing spring wheat crops in Western Australia can benefit livestock productivity. Crop and Pasture Science 2015, 66, 410 -417.

AMA Style

Dean T. Thomas, Andrew D. Moore, Hayley C. Norman, Clinton K. Revell. Small effects of deferment of annual pastures through grazing spring wheat crops in Western Australia can benefit livestock productivity. Crop and Pasture Science. 2015; 66 (4):410-417.

Chicago/Turabian Style

Dean T. Thomas; Andrew D. Moore; Hayley C. Norman; Clinton K. Revell. 2015. "Small effects of deferment of annual pastures through grazing spring wheat crops in Western Australia can benefit livestock productivity." Crop and Pasture Science 66, no. 4: 410-417.

Journal article
Published: 17 January 2014 in Grass and Forage Science
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This study examined how sheep develop a learned aversion to the annual legume biserrula (Biserrula pelecinus L.). Merino sheep were grazed on paddocks sown with either (i) biserrula, (ii) biserrula + ryegrass (Lolium rigidum Gaud.), (iii) crimson clover (Trifolium incarnatum L.), (iv) crimson clover + ryegrass or (v) ryegrass, for 4 weeks. Relative preference (Chesson–Manly selection index) was determined by offering randomly ordered monoculture plots of the three forage species. The groups of sheep were then combined into a single group and grazed a paddock containing a monoculture sward of each plant type for 5 d. Relative preference of sheep was tested again after the completion of the combined grazing. The experiment was repeated at three stages of plant phenology: vegetative, reproductive and senesced. Relative preference for biserrula was lower in sheep that had grazed the paddock sown with only biserrula compared with sheep that grazed a combination of biserrula + ryegrass, at both the vegetative (α; −0·11 vs. 0·32) and reproductive (α; 0·18 vs. 0·63) stages. At each stage of phenology, when groups were combined and grazed together, preference for biserrula became uniform. This supported the hypothesis that sheep develop an aversion to biserrula when they graze a pasture containing biserrula. However, we concluded that the familiarity of sheep with biserrula did not result in low relative preference; rather, the aversion was more likely a response to the high proportion of this plant in their diet. Social facilitation may have enabled sheep to overcome rapidly the food aversion.

ACS Style

D. T. Thomas; J. T. B. Milton; C. K. Revell; M. A. Ewing; D. R. Lindsay. Individual and socially learned preferences for biserrula ( Biserrula pelecinus L.) in sheep. Grass and Forage Science 2014, 70, 374 -380.

AMA Style

D. T. Thomas, J. T. B. Milton, C. K. Revell, M. A. Ewing, D. R. Lindsay. Individual and socially learned preferences for biserrula ( Biserrula pelecinus L.) in sheep. Grass and Forage Science. 2014; 70 (2):374-380.

Chicago/Turabian Style

D. T. Thomas; J. T. B. Milton; C. K. Revell; M. A. Ewing; D. R. Lindsay. 2014. "Individual and socially learned preferences for biserrula ( Biserrula pelecinus L.) in sheep." Grass and Forage Science 70, no. 2: 374-380.

Research article
Published: 01 January 2014 in Crop and Pasture Science
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Pasture cropping is an emerging farming-systems practice of southern Australia, in which winter grain crops are sown into an established stand of a winter-dormant, summer-growing perennial pasture. There is a pressing need to define times, locations and climates that are suitable for pasture cropping. To evaluate effects of management interventions, agro-environment, and possible interactions on crop and pasture productivity associated with pasture cropping, an AusFarm® simulation model was built to describe a pasture-cropping system based on annual crop and subtropical grass. The model was parameterised using data from field research on pasture cropping with barley cv. Buloke and a C4 subtropical grass, Gatton panic (Panicum maximum cv. Gatton), conducted at Moora, Western Australia. The simulation was run over 50 years using the historical climate data of five southern Australian locations (Cunderdin, Jerdacuttup, Mingenew, and Moora in Western Australia, and Karoonda in South Australia). Two wheat cultivars and one barley crop were considered for each location, to examine the impact of crop phenology on this farming system. Jerdacuttup and Moora favoured pasture cropping, with average barley-yield penalties of 10 and 12%. These locations were characterised by colder growing seasons, more plant-available water at anthesis, and more winter–spring rain. The cereal crops did not rely on stored soil moisture, growing instead on incident rain. The winter–spring growth of the Gatton panic pasture was highest at Mingenew. This generated a high yield penalty, 38% loss under pasture cropping, compared with the other locations. Changing the efficacy of a herbicide application to the pasture when the crop was sown had a strong effect on yield. Yield penalties at Moora and Mingenew reduced to 7 and 29%, respectively, when the proportion of live biomass killed by the herbicide was doubled. Utilisation of soil moisture by the Gatton panic pasture during summer and early autumn had little effect on subsequent grain yield, whereas reduced pasture growth during the winter–spring growing period had a substantial effect on crop yield. Pasture cropping can therefore succeed in agro-climatic regions where crops can be grown on incident rain and pasture growth is suppressed through low temperature or herbicide. Perennial pasture growth should be minimised during the crop growing period through the management of crop sowing date, nitrogen fertiliser application and C4 grass suppression to minimise the effect on stored soil water at crop anthesis.

ACS Style

Dean T. Thomas; Roger A. Lawes; Katrien Descheemaeker; Andrew D. Moore. Selection of crop cultivars suited to the location combined with astute management can reduce crop yield penalties in pasture cropping systems. Crop and Pasture Science 2014, 65, 1022 -1032.

AMA Style

Dean T. Thomas, Roger A. Lawes, Katrien Descheemaeker, Andrew D. Moore. Selection of crop cultivars suited to the location combined with astute management can reduce crop yield penalties in pasture cropping systems. Crop and Pasture Science. 2014; 65 (10):1022-1032.

Chicago/Turabian Style

Dean T. Thomas; Roger A. Lawes; Katrien Descheemaeker; Andrew D. Moore. 2014. "Selection of crop cultivars suited to the location combined with astute management can reduce crop yield penalties in pasture cropping systems." Crop and Pasture Science 65, no. 10: 1022-1032.

Journal article
Published: 03 August 2012 in Animals
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On-farm activities that reduce GHG emissions or sequester carbon from the atmosphere to compensate for anthropogenic emissions are currently being evaluated by the Australian Government as carbon offset opportunities. The aim of this study was to examine the implications of establishing and grazing Kikuyu pastures, integrated as part of a mixed Merino sheep and cropping system, as a carbon offset mechanism. For the assessment of changes in net greenhouse gas emissions, results from a combination of whole farm economic and livestock models were used (MIDAS and GrassGro). Net GHG emissions were determined by deducting increased emissions from introducing this practice change (increased methane and nitrous oxide emissions due to higher stocking rates) from the soil carbon sequestered from growing the Kikuyu pasture. Our results indicate that livestock systems using perennial pastures may have substantially lower net GHG emissions, and reduced GHG intensity of production, compared with annual plant-based production systems. Soil carbon accumulation by converting 45% of arable land within a farm enterprise to Kikuyu-based pasture was determined to be 0.80 t CO2-e farm ha−1 yr−1 and increased GHG emissions (leakage) was 0.19 t CO2-e farm ha−1 yr−1. The net benefit of this practice change was 0.61 t CO2-e farm ha−1 yr−1 while the rate of soil carbon accumulation remains constant. The use of perennial pastures improved the efficiency of animal production almost eight fold when expressed as carbon dioxide equivalent emissions per unit of animal product. The strategy of using perennial pasture to improve production levels and store additional carbon in the soil demonstrates how livestock should be considered in farming systems as both sources and sinks for GHG abatement.

ACS Style

Dean T. Thomas; Jonathan Sanderman; Sandra J. Eady; David G. Masters; Paul Sanford. Whole Farm Net Greenhouse Gas Abatement from Establishing Kikuyu-Based Perennial Pastures in South-Western Australia. Animals 2012, 2, 316 -330.

AMA Style

Dean T. Thomas, Jonathan Sanderman, Sandra J. Eady, David G. Masters, Paul Sanford. Whole Farm Net Greenhouse Gas Abatement from Establishing Kikuyu-Based Perennial Pastures in South-Western Australia. Animals. 2012; 2 (3):316-330.

Chicago/Turabian Style

Dean T. Thomas; Jonathan Sanderman; Sandra J. Eady; David G. Masters; Paul Sanford. 2012. "Whole Farm Net Greenhouse Gas Abatement from Establishing Kikuyu-Based Perennial Pastures in South-Western Australia." Animals 2, no. 3: 316-330.

Research article
Published: 01 January 2011 in Animal Production Science
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Relocating cattle from rangeland properties to agricultural pastures in southern Western Australia allows producers to improve year-round continuity of feed supply in their beef cattle businesses, and can reduce substantially the time taken to grow animals to meet market specifications. In this study the behaviour and growth of two groups of young cattle that were sourced from different locations was evaluated after they were transferred to a new extensive grazing system. In Experiment 1, 122 Limousin-cross heifers that were raised in the agricultural region of Western Australia (AR cattle) were transferred to the experimental site from a neighbouring property (~10 km away). In Experiment 2, 95 Brahman-cross heifers that were raised in the rangelands of Western Australia (RR cattle) were transferred to the experimental site. Animal growth and behaviour were analysed across time and differences in the time-course of behavioural changes between the groups were compared. Rate of liveweight gain in the AR cattle remained consistent (~1.2 kg/day) during the experiment. There was an increase in horizontal (16%; P < 0.001) and vertical (12%; P = 0.002) head movement in AR cattle over the first several weeks after relocation, indicative of increased grazing activity, but there was little change in other behaviours over the duration of the experiment. In contrast, the RR cattle had reduced growth during the first 4 weeks after relocation (P < 0.001). From weeks 2–4 weight gain in RR cattle was 0.31 kg/day, approximately one-quarter of their average daily gain attained 4 weeks later. During the first 6 weeks, RR cattle showed behavioural changes indicative of adaptation, including a 61% increase in horizontal head movements, suggesting more grazing activity. The paddock area utilised daily by RR cattle was 32% higher in week 6 compared with week 1, and during daylight hours (0600–1900 hours) they began to travel more (23%) and spent more time active (16%). We conclude that rangeland-raised Bos indicus heifers take from 4 to 6 weeks to adapt from their previous large paddocks/natural plant environment to a new temperate agricultural environment. Our results suggest that the cause of lost productivity in rangeland cattle when they are relocated to a temperate pasture is at least in part due to initial lower grazing activity as they become familiar with the new environment.

ACS Style

D. T. Thomas; M. G. Wilmot; R. W. Kelly; D. K. Revell. Adaptation behaviour of local and rangeland cattle relocated to a temperate agricultural pasture. Animal Production Science 2011, 51, 1088 -1097.

AMA Style

D. T. Thomas, M. G. Wilmot, R. W. Kelly, D. K. Revell. Adaptation behaviour of local and rangeland cattle relocated to a temperate agricultural pasture. Animal Production Science. 2011; 51 (12):1088-1097.

Chicago/Turabian Style

D. T. Thomas; M. G. Wilmot; R. W. Kelly; D. K. Revell. 2011. "Adaptation behaviour of local and rangeland cattle relocated to a temperate agricultural pasture." Animal Production Science 51, no. 12: 1088-1097.

Research article
Published: 01 January 2010 in Animal Production Science
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Grazing crop stubbles affects soil structure, groundcover, and the productivity of subsequent crops, but the cost of this practice is highly variable and not easily compared against the value of feed provided to livestock. To compare with and without grazing stubbles in terms of whole-farm profit and water-use efficiency we created a mixed enterprise farm model using the Agricultural Production Systems Simulator and GRAZPLAN biophysical simulation submodels, and the Model of Integrated Dryland Agricultural System linear programming model. We hypothesised that grazing crop stubbles would increase farm profit by an amount equivalent to the value of the metabolisable energy (ME) consumed by sheep when they grazed the crop stubbles. Representative mixed farms where sheep were or were not allowed to graze crop stubbles were compared for two locations in the wheatbelt of Western Australia (Cunderdin and Geraldton) at two stocking rates. Across locations and stocking rates, the estimated value of the ME intake from crop stubbles was 2.2 times the increase in farm gross margin when stubble grazing was allowed. Contributing to this difference was that stubble grazing provided a less flexible feed source than supplementary feeding and in the absence of adjustments in stocking rates sheep tended to utilise more of the annual and permanent pastures when stubble grazing was not permitted. Therefore, the value of grazing crop stubbles to the profitability of the farm enterprise was overestimated by the ME value of the intake. Owing to reduced consumption of supplementary feed by livestock, whole-farm water-use efficiency of protein production was increased by 15% when grazing of crop stubbles was permitted. This simulation study shows that the value of grazing crop stubbles cannot be predicted well using energy intake from stubble grazing or reduced supplementary feeding costs.

ACS Style

D. T. Thomas; J. Finlayson; A. D. Moore; M. J. Robertson. Profitability of grazing crop stubbles may be overestimated by using the metabolisable energy intake from the stubble. Animal Production Science 2010, 50, 699 -704.

AMA Style

D. T. Thomas, J. Finlayson, A. D. Moore, M. J. Robertson. Profitability of grazing crop stubbles may be overestimated by using the metabolisable energy intake from the stubble. Animal Production Science. 2010; 50 (7):699-704.

Chicago/Turabian Style

D. T. Thomas; J. Finlayson; A. D. Moore; M. J. Robertson. 2010. "Profitability of grazing crop stubbles may be overestimated by using the metabolisable energy intake from the stubble." Animal Production Science 50, no. 7: 699-704.

Research article
Published: 01 January 2010 in Animal Production Science
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We hypothesised that the preference of sheep among a wide range of annual legumes at successive stages of plant phenology would be related to laboratory measurements of the chemical composition of the forage. We tested this by examining the relative preferences of sheep among 20 genotypes of annual plants at three phenological stages of plant growth using the Chesson–Manly selection index. Plant material was collected for laboratory analyses at each phenological stage and samples were analysed for nitrogen, sulfur, neutral detergent fibre, acid detergent fibre, in vitro digestibility and water soluble carbohydrates. Sheep differed in relative preference among the plant genotypes within and between each of the three phenological stages. Vegetative characteristics that were correlated with relative preference also differed with plant phenology. Measured characteristics of the plant material explained an increasing proportion of the variance in relative preference with successive phenological stages (4.8, 51.1 and 60.9% at the vegetative, reproductive and senesced stages; P < 0.001). The relative preference of the sheep depended on the overall quality of the vegetation. When the quality of the vegetation was high, relative preference did not correlate well with measured nutritive characteristics. However, when the vegetation was of low quality, sheep selected plants with characteristics associated with higher nutritive value. We conclude that sheep adopt different foraging strategies in response to changing vegetation characteristics and increase their preference for plants that increase their intake of digestible dry matter as the sward matures.

ACS Style

D. T. Thomas; J. T. B. Milton; C. K. Revell; M. A. Ewing; R. A. Dynes; Kevin Murray; D. R. Lindsay. Preference of sheep among annual legumes is more closely related to plant nutritive characteristics as plants mature. Animal Production Science 2010, 50, 114 -123.

AMA Style

D. T. Thomas, J. T. B. Milton, C. K. Revell, M. A. Ewing, R. A. Dynes, Kevin Murray, D. R. Lindsay. Preference of sheep among annual legumes is more closely related to plant nutritive characteristics as plants mature. Animal Production Science. 2010; 50 (2):114-123.

Chicago/Turabian Style

D. T. Thomas; J. T. B. Milton; C. K. Revell; M. A. Ewing; R. A. Dynes; Kevin Murray; D. R. Lindsay. 2010. "Preference of sheep among annual legumes is more closely related to plant nutritive characteristics as plants mature." Animal Production Science 50, no. 2: 114-123.

Research article
Published: 01 January 2009 in Animal Production Science
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Grazing livestock on revegetated saline land is one of few profitable options to continue using this class of agricultural land. However, there has been little research conducted to assess the capability of saline land to support livestock production based on the soil and water characteristics at a particular site. In this study, data from 11 grazing studies collected from eight commercial farms across southern Australia were used to estimate metabolisable energy (ME) utilised/ha, as well as total ME produced/ha. All data were from the autumn (March–May) period, when feed is normally in short supply and of limited quality. Site characteristics indicative of the severity of salinisation varied across the sites. Topsoil electrical conductivity (ECe) ranged from 1 to 33 dS/m and groundwater EC from 14 to 60 dS/m (equivalent to sea water). Feed on offer before grazing varied from 700 kg dry matter/ha to 9000 kg dry matter/ha between sites. Thinopyrum ponticum and Puccinellia ciliata featured prominently in the less saline revegetated sites, with Atriplex spp. present on the more saline sites and some lucerne and rhodes grass on the less saline, well drained sites. Grazing days per ha for sheep (ME-adjusted dry sheep equivalent) on autumn pastures across the sites ranged from 41 to 3600, and liveweight gains ranged from –95 to 314 g/sheep.day. The grazing value of the highest producing saltland was at least as high as that expected on adjacent areas that were not salt affected. The major advantage of establishing saltland pastures included an out-of-season feed supply high in crude protein and micronutrients that possessed the ability to capture summer and autumn rain. This should represent a substantial reduction in supplementary feed costs and increases the flexibility of methods for feeding livestock through periods of low annual pasture availability. The value of the ME produced on the highest yielding saltland pasture was estimated to be $360/ha based on substituting the best alternative strategy of purchasing lupin grain as a supplement. A quadratic relationship (R2 = 0.62, P = 0.024) was found between soil ECe and ME produced across the sites. Significant relationships were not found between other saline site characteristics and ME production, which partly reflects the complexity of these systems as well as limitations with site characterisation.

ACS Style

D. T. Thomas; C. L. White; J. Hardy; J.-P. Collins; A. Ryder; H. C. Norman. An on-farm evaluation of the capability of saline land for livestock production in southern Australia. Animal Production Science 2009, 49, 79 -83.

AMA Style

D. T. Thomas, C. L. White, J. Hardy, J.-P. Collins, A. Ryder, H. C. Norman. An on-farm evaluation of the capability of saline land for livestock production in southern Australia. Animal Production Science. 2009; 49 (1):79-83.

Chicago/Turabian Style

D. T. Thomas; C. L. White; J. Hardy; J.-P. Collins; A. Ryder; H. C. Norman. 2009. "An on-farm evaluation of the capability of saline land for livestock production in southern Australia." Animal Production Science 49, no. 1: 79-83.

Research article
Published: 01 January 2008 in Australian Journal of Experimental Agriculture
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High ambient temperature can decrease weight gain in livestock, but domestic livestock in extensive grazing systems may have some capacity to adjust their behaviour to reduce the impact of periods of high temperature. We hypothesised that sheep grazing in the semiarid Southern Rangelands of Western Australia would reduce distance travelled on days with high mean daily temperature. Eight Merino ewes were fitted with GPS collars for 3 weeks in a 5575-ha paddock on Carlaminda station (28°20′S, 116°41′E). Mean daily temperature was used to separate the 18 days of the study into three temperature classes, cool (≤23.2°C), warm (23.3 to 25.9°C) and hot (≥26.0°C). Sheep travelled more quickly (P < 0.05) and further from water on cool days, compared with warm and hot days (3.74 v. 2.93 and 2.73 km from water, respectively; P < 0.001). On cool days, sheep spent most of their time grazing in the western area of the paddock. This area was rarely visited on warm or hot days. Mapping livestock distribution may assist in strategic relocation of existing water points and/or justify the development of additional watering points. However, our results suggest that sheep adjust their behaviour during hot weather, which may be a strategy to conserve energy, manage higher water requirements and/or reduce thermal load. Although grazing range decreases with higher temperatures, overall utilisation of a paddock may not be severely affected unless cooler days were too infrequent to facilitate regular access to these areas.

ACS Style

Dean T. Thomas; Matt G. Wilmot; Mark Alchin; David G. Masters. Preliminary indications that Merino sheep graze different areas on cooler days in the Southern Rangelands of Western Australia. Australian Journal of Experimental Agriculture 2008, 48, 889 -892.

AMA Style

Dean T. Thomas, Matt G. Wilmot, Mark Alchin, David G. Masters. Preliminary indications that Merino sheep graze different areas on cooler days in the Southern Rangelands of Western Australia. Australian Journal of Experimental Agriculture. 2008; 48 (7):889-892.

Chicago/Turabian Style

Dean T. Thomas; Matt G. Wilmot; Mark Alchin; David G. Masters. 2008. "Preliminary indications that Merino sheep graze different areas on cooler days in the Southern Rangelands of Western Australia." Australian Journal of Experimental Agriculture 48, no. 7: 889-892.

Journal article
Published: 01 January 2007 in Australian Journal of Agricultural Research
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For 8 weeks, 64 Merino wethers, 18 months of age, were individually penned and offered 1 of 16 treatment feeds (n = 4). The 16 feeds were formulated to contain levels of added sodium chloride (0, 7, 14, 21%) and levels of organic matter digestibility (55, 62, 69, 76%), in a 4 × 4 factorial design. The treatment feeds were offered ad libitum for 7 weeks and at maintenance for the final week. Clean wool growth, corrected for digestible organic matter intake, increased by 16, 18 and 27% as added sodium chloride was increased (7, 14, and 21%). The increase in wool growth was similar for diets at all levels of formulated organic matter digestibility. Feed digestibility in sheep decreased when added dietary sodium chloride was 14% or higher. The decrease in organic matter digestibility was ~5 percentage units at the highest level (21%) of dietary sodium chloride. Liveweight gain in sheep was reduced from 143 to 134, 65 and 1 g/day with 7, 14 and 21% added dietary sodium chloride, respectively. Therefore, improvement in wool growth efficiency appears to occur at the expense of liveweight gain, and was probably related to a shift in digestion of feed from the stomach to the small intestine. Higher corrected clean wool growth associated with lower levels of purine derivatives (an indicator of microbial protein synthesis) supported the conclusion that increased dietary salt resulted in an increase in dietary protein being digested in the small intestine. A shift in feed utilisation towards increased wool growth as dietary salt increases may be a management tool of particular interest to specialist wool producers. In areas of saline land where salt-accumulating shrubs are often the most productive vegetation, an increase in wool production efficiency, even if liveweight is only maintained, may improve the profitability of incorporating these shrubs into a feeding strategy.

ACS Style

Dean T. Thomas; Allan J. Rintoul; David G. Masters. Increasing dietary sodium chloride increases wool growth but decreases in vivo organic matter digestibility in sheep across a range of diets. Australian Journal of Agricultural Research 2007, 58, 1023 -1030.

AMA Style

Dean T. Thomas, Allan J. Rintoul, David G. Masters. Increasing dietary sodium chloride increases wool growth but decreases in vivo organic matter digestibility in sheep across a range of diets. Australian Journal of Agricultural Research. 2007; 58 (11):1023-1030.

Chicago/Turabian Style

Dean T. Thomas; Allan J. Rintoul; David G. Masters. 2007. "Increasing dietary sodium chloride increases wool growth but decreases in vivo organic matter digestibility in sheep across a range of diets." Australian Journal of Agricultural Research 58, no. 11: 1023-1030.