Physical Sciences and Mathematics Commons^™

Qtl Analysis Of Mineral Content In Perennial Ryegrass (Lolium Perenne L.), N. O. I. Cogan, A. C. Vecchies, T. Yamada, K. F. Smith, J. W. Forster

IGC Proceedings (1993-2023)

Variation in mineral content of grasses can be strongly influenced by genetic factors. Grass tetany (hypomagnesemia) of cattle and sheep is due to disturbances in serum magnesium levels. In Southern Australia, resultant levels of mortality in cattle vary between 0.5-1.5% of total stock numbers. Serum magnesium variation may be due to feed deficits, or dietary imbalances that interfere with magnesium metabolism. High levels of potassium appear to exert negative effects on the levels of magnesium in the blood. Italian ryegrass genotypes with high levels of magnesium can alleviate the incidence of grass tetany. The genetic control of mineral content, including …

A Molecular Study Of Alfalfa Megasporogenesis, D. Rosellini, Stefano Capomaccio, F. Veronesi

IGC Proceedings (1993-2023)

Our ability to control plant reproduction impacts on both seed production and plant breeding. A female sterility mutation was previously described (Rosellini et al., 1998; 2003) revealing a female-specific arrest of sporogenesis associated with ectopic, massive callose deposition within the nucellus. The goal of this study is to isolate and characterize genes involved in megasporogenesis and female sterility in alfalfa.

Modelling Grazing Animal Distributional Patterns Using Multi-Criteria Decision Analysis Techniques, M. R. George, N. R. Harris, N. K. Mcdougald, M. Louhaichi, M. D. Johnson, D. E. Johnson, K. R. Smith

IGC Proceedings (1993-2023)

Predicting livestock distribution is crucial to reducing livestock impacts on environmentally critical areas. Attempts to model livestock distribution on rangelands have met with varying levels of success. Most of these models described conditions at specific sites and did not work well when they were applied to other sites. In part, the weakness of these models arises from a lack of connection to the spatial arrangement of the study area and the pattern shown by animal distributions. To model the influence of the factors on livestock distribution we developed the Kinetic Resource and Environmental Spatial Systems (KRESS) Modeller. The KRESS Modeler …

Species Richness, Species Identity And Ecosystem Function In Managed Temperate Grasslands, S. C. Goslee, M. A. Sanderson, K. Soder

IGC Proceedings (1993-2023)

Manipulation of plant species diversity may provide a way to improve the ecosystem functioning of managed systems by increasing productivity and suppressing weedy species. As yet, the functional role of species richness is not well-enough understood to enable practical application. We investigated the effects of differing species richness on community stability and invasion resistance in a grazed temperate grassland.

Preference Of Goats For Cool-Season Annual Clovers In The Southern United States, Thomas H. Terrill, W. F. Whitehead, G. Durham, Carl S. Hoveland, B. P. Singh, S. Gelaye

IGC Proceedings (1993-2023)

In the southern U.S.A., annual clovers provide high-quality winter and spring grazing for beef cattle and sheep. New Zealand data on white clover (Trifolium repens L.) suggests that goats do not prefer this plant as much as sheep (Clark et al., 1982) but little data are available on willingness of goats to consume different clover types in the USA.

Production Per Animal And Use Of Intake Estimatives To Predicted Animal Productivity In Pennisetum Purpureum Cv. Mott And Cynodon Spp Cv. Tifton 85 Pastures, Fernando L. F. De Quadros, A. R. Maixner, Gilberto V. Kozloski, D. P. Montardo, A. Noronha, D. G. Bandinelli, M. Da S. Brum, N. D. Aurélio

IGC Proceedings (1993-2023)

Dairy production is a very important activity in southern Brazil, being an essential source of income to small household farms. Milk production from pastures is an alternative to reduce costs in dairy systems. Some C4 grasses, such as dwarf elephant grass (DEG) and Tifton 85, have presented high animal production per animal and per area. Although studies evaluating milk production from these pastures are rare in south Brazil, in vitro studies have demonstrated that the nutritional value of these forages is higher than production registered in grazing. So, it is possible that, in spite of a high intrinsic nutritional value, …

Ingestive Behaviour Of Steers In Native Pastures In Southern Brazil, C. E. Pinto, Paulo C. De F. Carvalho, A. Frizzo, J. A.S.F. Júnior, T. M. S. Freitas, Carlos Nabinger

IGC Proceedings (1993-2023)

The Campos biome, particularly its native pastures, is the main resource for livestock production in southern Brazil (Boldrini, 1997). It has a huge floristic diversity in which more than 400 grass and 150 legume species are found. These pastures are very heterogeneous with horizontal as well as vertical structure. Hodgson (1985) stressed the importance of sward structure upon diet selection, emphasizing the difficulties animals could have to access all pasture layers in temperate pastures. This experiment investigates how variation in herbage allowance along the growing season influences the ingestive behaviour of steers.

The Efficacy Of Genethresher® Methylation Filtering Technology In The Plant Kingdom, U. Warek, J. A. Bedell, M. A. Budiman, A. N. Nunberg, R. W. Citek, D. Robbins, N. Lakey, P. D. Rabinowicz

IGC Proceedings (1993-2023)

The genomes of many plants are known to be composed of a large fraction of repetitive DNA, while a small portion is dedicated to genes. The bulk of the repetitive DNA constitutes transposable elements and is heavily methylated. GeneThresher technology has been developed to take advantage of these differential methylation patterns by filtering genomic shotgun libraries to exclude methylated sequences (Rabinowicz et al., 1999; Palmer et al., 2003; Martienssen et al., 2004). The result is a gene-enriched genomic shotgun library. Random shotgun sequencing of plant gene space, enabled by GeneThresher technology, is a rapid and cost-effective strategy …

Translational Genomics For Alfalfa Varietal Improvement, G. D. May

IGC Proceedings (1993-2023)

Key points

1. Medicago truncatula is a model legume with available mapping, genome, and RNA, protein and metabolite profiling databases and genetically diverse populations.
2. Genomics resources developed for M. truncatula have application in the study and improvement of alfalfa making it an excellent model for this forage legume.

Species Richness Affects Grassland Yield And Yield Stability Across Seasons, Sites And Years, David J. Barker, Reuben M. Sulc, M. R. Burgess, T. L. Bultemeier

IGC Proceedings (1993-2023)

The benefits of biodiversity (specifically species richness) are proposed to include both greater yield and greater stability of yield in a variable environment (Sanderson et al., 2004). Experimental evidence showing yield benefits is inconsistent (White et al., 2004). There is relatively little experimental data showing the effects of species richness on yield stability. The objective of this study was to measure the yield from mixtures with up to 12 species, and to measure the variability of yield between 2 sites, between spring and summer, and in 2 successive years.

Protection Of Agrobiodiversity: Model Calculations In Rhineland-Palatia: Costs And Implications For Farmers, H. Bergmann

IGC Proceedings (1993-2023)

Biological conservation and production use the same areas of land in less favoured areas. Grassland in these areas makes an important contribution to the protection of agro-biodiversity. However, under existing market conditions and production needs, the use of low yielding grasslands is not economically efficient. The objective of this study was to analyze the economic consequences of different mowing strategies in a small region in Rhineland-Palatia (Germany) that served the protection of two butterfly species.

Discovery And Functional Categorisation Of Expressed Sequence Tags From Flowers Of Eragrostis Curvula Genotypes Showing Different Ploidy Levels And Reproductive Modes, V. Echenique, S. Felitti, N. Paniego, L. Martelotto, S. C. Pessino, D. Zanazzi, P. Fernández, M. Díaz, P. Polci, G. C. Spangenberg

IGC Proceedings (1993-2023)

Two novel genotypes of weeping lovegrass (Eragrostis curvula) - a dihaploid strain obtained in vitro from an apomictic cultivar and a tetraploid plant derived from the dihaploid after chromosome duplication – have recently been developed. These materials represent an excellent system for the identification, through transcriptional profiling, of genes involved in diplospory and/or ploidy level gene regulation. The aim of this work was the discovery and functional classification of expressed sequence tags (ESTs) from immature inflorescences of the apomictic E. curvula cultivar Tanganyika (2n=4x=40), a dihaploid sexual strain derived from it (2n=2x=20) and a tetraploid sexual strain …

Stocking Rate Theory And Profit Drivers In North Australian Rangeland Grazing Enterprises, Neil D. Macleod, A. J. Ash, John G. Mcivor

IGC Proceedings (1993-2023)

Setting correct stock numbers is a key decision for successful pastoralism. In marginal environments, typified by northern Australia, this involves careful cattle herd management across landscapes and seasons characterised by heterogeneous land condition and extreme climatic uncertainty. Stocking rate theory which links animal production to stocking rates concentrates only on liveweight gain of sale animals and ignores complex herd (e.g. reproduction, mortality) and pasture dynamics (e.g. land condition) and costs of maintaining stock numbers (e.g. supplementary feeding). Related economic models are generally naïve and incomplete, being based on liveweight gain, meat prices and variable husbandry costs (e.g. Workman, 1986). Modelling …

An Ecological And Economic Risk Avoidance Drought Management Decision Support System, R. K. Heitschmidt, L. T. Vermeire

IGC Proceedings (1993-2023)

Ecologists have long recognized the fundamental impacts of drought on rangeland structure and function. Simulation models have been developed to increase our understanding of these impacts as they relate to forage production, particularly for predictive purposes. Although the capacity of these models to accurately predict quantity and quality of forage produced under varying climatic conditions is often quite good, their ability to serve as an effective and proactive drought management decision support system is often limited. This is in large part because their complexity impedes their use by on-the-ground managers. The objective of this research was to develop a very …

Managing Resources By Grazing In Grasslands Dominated By Dominant Shrub Species, D. Magda, Cyril Agreil, Michel Meuret, E. Chambon-Dubreuil, P. -L. Osty

IGC Proceedings (1993-2023)

The European natural grasslands are attracting new attention because of their environmental value as habitats for threatened fauna and flora species and their contribution to the diversity of landscapes. Those responsible for the implementation of the European agri-environmental policy are hence encouraging livestock farmers to adopt grazing practices that contribute to the conservation of grassland biodiversity especially by limiting encroachment by dominant shrubs. However, current scientific knowledge and technical information are often insufficient to connect flock feeding and the impact of grazing on shrub dynamics and livestock farmers are not very enthusiastic about restoring or conserving “plant mosaics” including shrubs …

Predicting The Effects Of Management On Upland Birds, Economy And Employment, S. M. Gardner, G. M. Buchanan, J. W. Pearce-Higgins, M. C. Grant, A. Waterhouse

IGC Proceedings (1993-2023)

Livestock farming systems play a significant role in the economy and conservation of the UK uplands and rely heavily upon public financial support. Changes in that support could have far-reaching impacts on the wildlife interest and socio-economics of upland areas. Predicting the impacts of such changes is difficult, since they arise from responses to new economic circumstances. The effect of management change is also influenced by natural variation, such as the mosaic of plant communities, already present in the upland landscape. This paper sets out an approach that integrates theoretical models with field studies to investigate the effects of management …

Challenges In Modelling Live-Weight Change In Grazed Pastures In The Australian Subtropics, C. K. Mcdonald, A. J. Ash

IGC Proceedings (1993-2023)

In sub-tropical regions there is enormous seasonal, annual and spatial variation in pasture quality and considerable variation in quality between pasture species. The heterogeneous structure of sub-tropical pasture swards means that process based modelling of liveweight change (LWC) is particularly difficult. In response to this complexity LWC has been expressed as a function of the length of the growing season and/or pasture utilization (McKeon et al. 2000), green leaf availability, or pasture availability and climate (Hirata et al. 1993). However, these relationships vary from year to year, often fail when species composition changes, and generally explain

Vegetation Dynamics Of Campos Under Grazing/Fire Regimes In Southern Brazil, Fernando L. F. De Quadros, J. P. P. Trinidade, D. G. Bandinelli, L. Pötter

IGC Proceedings (1993-2023)

Natural grassland vegetation in Southern Brazil, known as campos, has most likely evolved under a disturbance regime that included fire and grazing (Pillar et al., 1997). Nowadays, the composition of the vegetation of campos is grazing- and fire-dependent (Boldrini et al., 1997). Its importance can be evaluated by the fact that it represents 37 % of the state’s area and provides 77 % of the slaughtered cattle at Rio Grande do Sul (Barcellos et al., 2002). The objective of this experiment was to evaluate the vegetation dynamics of campos under grazing/fire regimes in order to explore the …

Accumulation Of Polyphenols And Major Bioactive Compounds In Plantago Lanceolata L. As A Medicinal Plant For Animal Health And Production, Y. Tamura, K. Yamaki

IGC Proceedings (1993-2023)

Producing animals without the use of feed-grade antibiotic growth promoters and chemical medicines is sought. Scientific studies with this aim have focused on medicinal plants to identify and quantify any beneficial effects that they might have on animal production. Plantago lanceolata L. has been used in herbal medicines and is currently being evaluated as a potential pasture species because of its beneficial effects on animal health. In the present study, the accumulation of polyphenols in P. Lanceolata is compared to that in principal pasture species, and genetic variation and environmental changes in the major bioactive compounds in P. Lanceplata are …

Effect Of Urea-Treated Pennisetum Pedicellatum And Supplementation Of Concentrates With Urea On Milk Production Of “Mossi” Ewes, V. M. C. Bougouma-Yameogo, A. J. Nianogo

IGC Proceedings (1993-2023)

The “Mossi” sheep is a near parent of “Djallonke” sheep that live in sudano-sahelian area of Burkina Faso. However, there are few available results on dairy production from this breed. The treatment of straw with urea is a technique used in several developing countries to improve the nutritional value of gramineous forages (Sourabié et al., 1995). The aim of this study was to test the influence on the performance of “Mossi” ewes and on milk composition of treatment of Pennisetum pedicellatum (Pp) with urea in comparison with addition of urea to the concentrate feed.

Effect Of Stocking Rate On A Stipa Breviflora Desert Steppe Community Of Inner Mongolia, G. Han, Walter D. Willms, M. Zhao, A. Gao, S. Jiao, David R. Kemp

IGC Proceedings (1993-2023)

Stocking rate is an important factor in grazing management. The stocking rate defines utilization and ultimately grazing pressure, which in turn affects grassland sustainability. Grassland sustainability is partly defined by its species composition and ultimately by its productivity. These attributes are unique for specific plant communities and the effect of stocking rate must be established for each in order to understand the community response to grazing and to determine its carrying capacity. While some information exists on the effects of stocking rate on livestock production in the Stipa breviflora Griseb. Desert Steppe (Wei et al., 2000), the effects on …

Using The N-Alkane Technique To Estimate The Herbage Intake And Diet Composition Of Cattle Grazing A Miscanthus Sinensis Grassland, Y. Zhang, Y. Togamura, K. Otsuki

IGC Proceedings (1993-2023)

Plant wax alkanes are now widely used as marker substances (Dove & Mayes 1991) for the estimation of forage intake and diet composition of grazing herbivores. The objective of this study was to evaluate this method with cattle grazing a M. sinensis grassland in Japan.

Reasons For The Premature Decline In Astragalus Adsurgens Stands In Kerqin Sandy Land, Qizhong Sun, Z. L. Wang, J. G. Han, Y. W. Wang, G. R. Liu

IGC Proceedings (1993-2023)

Diseases partly account for reductions in Astragalus adsurgens stand longevity. The effect of some cultural practices on the control of pests and diseases have been reported (Hou, 1986; Nan, 1996), but few reports have detailed the relationship among soil fertiliser status, diseases and premature stand decline. This study was conducted to investigate these relationships in order to extend the longevity of Astragalus adsurgens stands.

Selecting Grassland Species For Saline Environments, M. E. Rogers, A. D. Craig, T. D. Colmer, R. Munns, S. J. Hughes, P. M. Evans, P. G. H. Nichols, R. Snowball, D. Henry, J. Deretic, B. Dear, M. Ewing

IGC Proceedings (1993-2023)

In Australia, around 5.7 million hectares of agricultural land are currently affected by dryland salinity or at risk from shallow water tables and this figure is expected to increase over the next 50 years (LWRA, 2001). Most improved grassland species cannot tolerate the combined effects of salt and waterlogging and, therefore, the productivity of sown grasslands in salt-affected areas is low. However, there is potential to overcome the lack of suitably adapted fodder species by introducing new, salt and waterlogging-tolerant species and by diversifying the gene pool of proven species. Potential species include exotic, naturalised and native Australian grass, legumes, …

Effects Of The Stage Of Growth And Inoculation On Proteolysis In Field Pea Silage, L. Cavallarin, G. Borreani, S. Antoniazzi, E. Tabacco

IGC Proceedings (1993-2023)

Ensiling legumes is a good way of providing home-grown protein in dairy farms but severe protein degradation can occur when conserving legumes. Peas (Pisum sativum L.) are legumes with a high crude protein and starch content, that provide a high forage yield in a short growing period. Very little information is available on the protein value of field pea silage. The aim of the study was to investigate the effect of stage of maturity and inoculant application on proteolysis in field pea silage in the Po Valley, NW Italy.

Grass Silage: Factors Affecting Efficiency Of N Utilisation In Milk Production, P. Huhtanen, K. J. Shingfield

IGC Proceedings (1993-2023)

Key points

1. Low efficiency of N utilisation for milk production in cows fed grass silage-based diets is mainly due to excessive N losses in the rumen.
2. The type and extent of in silo fermentation can alter the balance of absorbed nutrients.
3. There is very little experimental evidence that the capture of N in the rumen can be improved by a better synchrony between energy and N release in the rumen. Nitrogen losses in the rumen can be reduced by decreasing the ratio between rumen degradable N and fermentable energy.
4. Rapeseed meal has increased milk protein output more than isonitrogenous soybean …

Decision Support For Grassland Systems In Developing Countries, P. K. Thornton

IGC Proceedings (1993-2023)

Key points

1. Information flows in complex systems are often themselves highly complex, and decision support approaches based on linear input-output processes may have only limited impact.

2. How decisions are made, and how they can be appropriately supported, is often incompletely understood, in part because of inadequate understanding of the objectives and attitudes of all the decision makers involved.

3. Much of the developing world faces daunting problems in the coming 30 years, and appropriate information could play a critical role in dealing with these.

4. System complexity, household variability, and institutional intricacies have to be embraced rather than …

Breeding Milestones Correspond With Changes To Wheat Rhizosphere Biogeochemistry That Affect P Acquisition, Rebecca Kay Mcgrail, David A. Van Sanford, David H. Mcnear Jr.

Plant and Soil Sciences Faculty Publications

Breeding wheat (Triticum aestivum L.) has resulted in small gains in improved nutrient acquisition and use as numerous traits are involved. In this study, we evaluated the impact of breeding on P-acquisition and identified both plant and soil variables that could be used to inform the selection of germplasm with increased P acquisition efficiency. We previously screened a historic panel of winter wheat cultivars for root system architecture and root tip organic acid content when grown in P-deficient solution/agar and used these characteristics together with breeding history to develop a predicted P extraction potential (PEP). We tested the validity …

An Ecosystem Modelling Approach To Rehabilitating Semi-Desert Rangelands Of North Horr, Kenya, G. A. Olukoye, W. N. Wamicha, J. I. Kinyamario

IGC Proceedings (1993-2023)

Decreased rainfall, recurrent droughts and increased anthropogenic activities have led to a dramatic increase in wind erosion on pastoral lands of North Horr resulting in the reactivation of the once-stable sand dunes. This has degraded the vegetation and impoverished the local community. Mobile sand has a severe impact on dry season grazing areas (Omar & Abdal, 1994) and, therefore, affects pastoral livestock production. In North Horr, Suaeda monoica is important in camel production and for stabilising sand dunes but it has been over-utilized over the years. The objective of this study was to use ecosystem modelling approaches to examine the …

Riparian Management In Intensive Grazing Systems For Improved Biodiversity And Environmental Quality: Productive Grazing, Healthy Rivers, S. R. Aarons, M. Jones-Lennon, P. Papas, N. Ainsworth, F. Ede, J. Davies

IGC Proceedings (1993-2023)

Within high rainfall intensive grazing systems of southern Victoria, riparian zones are often degraded due to vegetation clearing, stock access and inappropriate farm management. Streams in these landscapes often have poor water quality and reduced biodiversity due to degraded terrestrial and aquatic ecosystems. Improved management of riparian zones depends on developing tools and practices for integration into productive grazing systems. This paper describes the approaches used and the tools developed in the ‘Productive Grazing, Healthy Rivers: Improving riparian and in-stream biodiversity’ project.