Will current rotational grazing management recommendations suit future intensive pastoral systems?

This review aimed to determine whether current grazing management practices will suit future intensive rotationally grazed pastoral systems. A review of literature on grazing management recommendations found that there was good agreement on the ‘principles’ required for optimal grazing management. While these management practices have stood the test of time, it is concluded that shifts in external pressures (e.g., climate, plant selection and breeding, system intensification) compared to the period when farm-level grazing recommendations were first developed, may necessitate a rethink of current grazing recommendations. Examples include greater pasture masses (e.g., around 4000 kg dry matter (DM)/ha vs. the recommended range of 2600 to 3200 kg DM/ha) where short-rotation (annual, biennial) and tetraploid ryegrasses are sown, provided a consistent post-grazing residual can be maintained (possibly between 40- and 70- mm height). Milder winters and the use of ryegrass cultivars with higher growth rates in late winter/early spring may necessitate either lower target pasture covers at calving or shorter rotation lengths during winter. Longer grazing rotations (well beyond the 3-leaf stage, i.e., equivalent to deferred grazing) can be recommended for select paddocks from mid-spring into summer, to increase seasonal resilience across the farm. Longer residuals (even up to 70 mm - i.e., almost double the recommended height) might improve plant survival during periods of high stress (e.g., heatwaves, droughts). Lastly, diverse species pastures may require specific management to suit dominant species other than perennial ryegrass

Validation of Genotyping by Sequencing Using Transcriptomics for Diversity and Application of Genomic Selection in Tetraploid Potato

Potato is an important food crop due to its increasing consumption, and as a result, there is demand for varieties with improved production. However, the current status of breeding for improved varieties is a long process which relies heavily on phenotypic evaluation and dated molecular techniques and has little emphasis on modern genotyping approaches. Evaluation and selection before a cultivar is commercialized typically takes 10–15 years. Molecular markers have been developed for disease and pest resistance, resulting in initial marker-assisted selection in breeding. This study has evaluated and implemented a high-throughput transcriptome sequencing method for dense marker discovery in potato for the application of genomic selection. An Australian relevant collection of commercial cultivars was selected, and identification and distribution of high quality SNPs were examined using standard bioinformatic pipelines and a custom approach for the prediction of allelic dosage. As a result, a large number of SNP markers were identified and filtered to generate a high-quality subset that was then combined with historic phenotypic data to assess the approach for genomic selection. Genomic selection potential was predicted for highly heritable traits and the approach demonstrated advantages over the previously used technologies in terms of markers identified as well as costs incurred. The high-quality SNP list also provided acceptable genome coverage which demonstrates its applicability for much larger future studies. This SNP list was also annotated to provide an indication of function and will serve as a resource for the community in future studies. Genome wide marker tools will provide significant benefits for potato breeding efforts and the application of genomic selection will greatly enhance genetic progress

The role of forage management in addressing challenges facing Australasian dairy farming

Forage management underpins the viability of pastoral dairy systems. This review investigated recent developments in forage research and their potential to enable pastoral dairy systems to meet the challenges that will be faced over the next 10 years. Grazing management, complementary forages, pasture diversity, fertiliser use, chemical restriction, irrigation management and pasture breeding are considered. None of these areas of research are looking to increase production directly through increased inputs, but, rather, they aim to lift maximum potential production, defend against production decline or improve the efficiency of the resource base and inputs. Technology approaches consistently focus on improving efficiency, while genetic improvement or the use of complementary forages and species diversity aim to lift production. These approaches do not require additional labour to implement, but many will require an increase in skill level. Only a few areas will help address animal welfare (e.g. the use of selected complementary forages and novel endophytes) and only complementary forages will help address increased competition from non-dairy alternatives, by positively influencing the properties of milk. Overall, the diversity of activity and potential effects will provide managers of pastoral dairy systems with the best tools to respond to the production and environmental challenges they face over the next 10 years

Harvest management based on leaf stage of a tetraploid vs. a diploid cultivar of annual ryegrass

Leaf stage-dependent defoliation is linked to the plant's physiological status and may be a more suitable criterion than time-based intervals for harvesting forage grasses, but no reports of research with annual ryegrass (Lolium multiflorum Lam. var. westerwoldicum) were found. To address this, a 2-year field study was carried out at Raymond, MS, on a Loring silt loam soil (fine-silty, mixed, thermic Typic Fragiudalfs). Forage production, morphological characteristics and nutritive value responses to defoliation based on leaf stage (2, 3 and 4 leaves per tiller) and two residual stubble heights (RSH 5 and 10 cm) of a tetraploid ("Maximus") vs. a diploid ("Marshall") cultivar of annual ryegrass were quantified. Forage harvested, in 2011, increased linearly as leaf stage increased from 7.3 to 8.8 Mg/ha, but during 2012 was least (7.0 Mg/ha) at 3-leaf stage and similar at the other two leaf stages (7.6 Mg/ha). Tiller density was less for Maximus (1,191 tillers/m(2)) than for Marshall (1,383 tillers/m(2)). Leaf blade proportion decreased with increasing leaf stage and was greater by 9% for Maximus than for Marshall. Generally, forage nutritive value became less desirable with increasing leaf stage. There was a dichotomy in forage harvested and nutritive value responses, but maximum forage productivity was achieved when annual ryegrass was defoliated at the 4-leaf stage interval

Genetic Improvement of Perennial Forage Plants for Salt Tolerance

The difficulties of genetic improvement of forage species are further complicated by the intricacies of salinity stress. Multiple evidence of the effects of salinity on germination and establishment highlight some of the limitations that must be overcome in order to carry out successful breeding programs for pastures. Different sources of variation feasible to be used in such breeding programs areanalyzed. The application of morpho-physiological selection criteria such as “salt glands” or “Na exclusion,” simulation of the saline environment to assess germination behavior, initial growth or production before defoliation are considered. Methodological advances in sequencing and bioinformatics allow us to predict a prominent role in the application of “Genomic Selection”. On the other hand, the advances in gene technologies have allowed direct the changes to specific sites by “Gene Edition” techniques, which are also very promising. The different methodologies of population management are largely dependent on reproductive systems, and it is a field where knowledge and “art” combine for successful results in plant breeding. Conclusions are drawn from the experiences carried out, and future perspectives for the improvement of perennial forage are analyzed. Both classical and molecular breeding come together not as alternatives but as complements.Fil: Schrauf, Gustavo Enrique. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Alonso Nogara, Flavia Alejandra. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Rush, Pablo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Peralta Roa, Pablo Leonel. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Musacchhio, Eduardo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Sergio Ghio. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Couso, Luciana Laura. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ramos, Elena. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Schrauf, Matías Florián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Voda, Lisandro. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Giordano, Andrea Mariana. La Trobe University; Australia. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Giavedoni, Julio Alberto. Universidad Nacional del Litoral; ArgentinaFil: Pensiero, José F.. Universidad Nacional del Litoral; ArgentinaFil: Tomas, Pablo. Universidad Nacional del Litoral; ArgentinaFil: Zabala, Juan M.. Universidad Nacional del Litoral; ArgentinaFil: Spangenberg, Germán. La Trobe University; Australi