For Australian and New Zealand dairy farms the primary source of home grown feed comes from grazed perennial pastures. The high consumption of perennial pasture is a key factor in the low cost of production of Australian and New Zealand dairy systems and hence their ability to maintain international competiveness. The major pasture species used are perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), normally grown in a simple binary mixture. As pasture production has been further driven by increasing use of nitrogen fertilizer and irrigation, farms are getting closer to their economic optimum level of pasture consumption. Increasing inputs and intensification has also increased scrutiny on the environmental footprint of dairy production. Increasing the diversity of pasture species within dairy swards presents opportunities to further increase the productivity of the feedbase through additional forage production, extending the growing season, improving forage nutritive characteristics and ultimately increasing milk production per cow and/or per ha. Diverse pastures also present an opportunity to mitigate some of the environmental consequences associated with intensive pasture-based dairy systems. A consistent finding of experiments investigating diverse pastures is that their benefits are due to the attributes of the additional species, rather than increasing the number of species per se. Therefore the species that are best suited for inclusion into dairy pastures will be situation specific. Furthermore, the presence of additional species will generally require modification to the management principles of dairy pastures, particularly around nitrogen fertilizer and grazing, to ensure that the additional species remain productive and persistent.

There is a growing interest in the use of deficit irrigation and perennial pasture species other than perennial ryegrass (Lolium perenne L.) in temperate agriculture, in response to the decreasing availability of irrigation water. Deficit irrigation requires an understanding of plant responses to drought stress to ensure maximum dry‐matter return on water applied. A glasshouse study was undertaken to investigate some of the morphological and physiological responses of perennial ryegrass, cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus phoenix Scop.) to varied moisture availability. One water treatment involved frequent applications of water to maintain a soil water potential of approximately −10 kPa (100% treatment), and three other treatments involved applications at the same frequency, but using 33, 66 or 133% of the water applied in the 100% treatment. The water treatments continued over two plant regrowth cycles, followed by a ‘recovery’ phase of a single regrowth cycle during which all plants received the same water allocation as the 100% treatment. Depletion and replenishment of stubble water‐soluble carbohydrate (WSC) differed between the three species in response to soil moisture availability. By the second regrowth cycle, stubble WSC concentration and content in moisture‐stressed cocksfoot plants had increased, followed by a decrease during the subsequent recovery phase when the stored WSC reserves were utilized to support regrowth. The changes in stubble WSC reserves corresponded to the maintenance of relatively stable (i.e. the smallest reduction in leaf DM in response to moisture stress), but consistently lower DM production for cocksfoot compared with the other species. In contrast, moisture stress had no effect on the stubble WSC reserves of perennial ryegrass and tall fescue, with the exception of a significant decrease in WSC concentration under the 33% water treatment for perennial ryegrass. Perennial ryegrass achieved an intermediate DM yield and maintained positive growth rates throughout the study, even when watered at 33% of the requirement for optimal soil moisture levels. However, a more pronounced reduction in leaf DM in plants under moisture stress compared with the other species, combined with declining WSC reserves and the death of daughter tillers, highlighted the vulnerability of perennial ryegrass to poor persistence under prolonged drought conditions. Tall fescue appeared to have the greatest scope under moisture stress in terms of maintaining productivity and displaying attributes that contribute to persistence. Its leaf DM was consistently greater than that of the other species, displaying a smaller decline in growth under water stress compared to perennial ryegrass and an ability to recover faster upon re‐watering. This study has expanded the information available that compares and defines the potential of each species under moisture stress and emphasizes the importance of balancing short‐term DM production with long‐term ...

There is interest in the reincorporation of legumes and forbs into pasture-based dairy production systems as a means of increasing milk production through addressing the nutritive value limitations of grass pastures. The experiments reported in this paper were undertaken to evaluate milk production, blood metabolite concentrations, and forage intake levels of cows grazing either pasture mixtures or spatially adjacent monocultures containing perennial ryegrass (Lolium perenne), white clover (Trifolium repens), and plantain (Plantago lanceolata) compared with cows grazing monocultures of perennial ryegrass. Four replicate herds, each containing 4 spring-calving, cross-bred dairy cows, grazed 4 different forage treatments over the periods of early, mid, and late lactation. Forage treatments were perennial ryegrass monoculture (PRG), a mixture of white clover and plantain (CPM), a mixture of perennial ryegrass, white clover, and plantain (RCPM), and spatially adjacent monocultures (SAM) of perennial ryegrass, white clover, and plantain. Milk volume, milk composition, blood fatty acids, blood β-hydroxybutyrate, blood urea N concentrations, live weight change, and estimated forage intake were monitored over a 5-d response period occurring after acclimation to each of the forage treatments. The acclimation period for the early, mid, and late lactation experiments were 13, 13, and 10 d, respectively. Milk yield (volume and milk protein) increased for cows grazing the RCPM and SAM in the early lactation experiment compared with cows grazing the PRG, whereas in the mid lactation experiment, milk fat increased for the cows grazing the RCPM and SAM when compared with the PRG treatments. Improvements in milk production from grazing the RCPM and SAM treatments are attributed to improved nutritive value (particularly lower neutral detergent fiber concentrations) and a potential increase in forage intake. Pasture mixtures or SAM containing plantain and white clover could be a strategy for alleviating the nutritive limitations of perennial ryegrass monocultures, leading to an increase in milk production for spring calving dairy cows during early and mid lactation.

Running head: Resilience of forage crops to climate change 2 Modeling the resilience of forage crop production to future climate change in the dairy regions of south eastern Australia using APSIM. SUMMARYA warmer and a potentially drier future climate is likely to influence the production of forage crops on dairy farms in the south east dairy regions of Australia. Biophysical modelling was undertaken to explore the resilience of forage production of individual forage crops to scalar increases in temperature, atmospheric CO 2 concentration and changes in daily rainfall. The model APSIM was adapted to reflect species specific responses to growth under elevated atmospheric CO 2 concentrations. It was then used to simulate 40 years of production of forage wheat, oats, annual ryegrass, maize grown for silage, forage sorghum, forage rape and alfalfa grown at three locations in south east Australia with increased temperature scenarios (1, 2, 3 and 4 o C of warming) and atmospheric CO 2 concentration (435, 535, 640 and 750 ppm) and decreasing rainfall scenarios (10, 20 or 30% less rainfall). At all locations positive increases in DM yield compared to the baseline climate scenario were predicted for lucerne (2.6 to 93.2% increase), wheat (8.9 to 37.4% increase), oats (6.1 to 35.9% increase) and annual ryegrass (9.7 to 66.7% increase) under all future climate scenarios. The response of forage rape and forage sorghum varied between location and climate change scenario.Without a decrease in rainfall, forage sorghum yield increased at Elliott by between 4.7 and 40.9%. At Dookie forage sorghum yield decreased by between 1.1 and 13.9% under all the future climate scenarios, while at Terang yield decreased by between 0.4 and 16.3% for all senarious except for the 1 o C increase in temperature with no change in rainfall. At Elliott and Terang with no change in rainfall forage rape yield increased by between 3.4 and 12.6% up to a 4 o C increase in temperature. At Dookie with a decrease in rainfall forage rape yield decreased by between 0.2 and 4.6%. A decrease in forage rape yield at Elliott and Terang only occurred with a 20 and 30% decrease in rainfall. At all locations maize was predicted to have a minimal change in yield under all future climates (between a 2.6% increase and a 6.8% decrease). The future climate scenarios altered the seasonal pattern of forage supply for wheat, oats and lucerne with a increase in forage produced during winter. The resilience of forage crops to climate change indicates that they will continue to be an important component of dairy forage production in south eastern Australia.3

Grassland production systems contribute 40% to Australia’s gross agricultural production value and utilise >50% of its land area. Across this area, diverse systems exist, but these can be broadly classified into four main production systems: (i) pastoral grazing, mainly of cattle at low intensity (i.e. <0.4 dry sheep equivalents/ha) on relatively unimproved native rangelands in the arid and semi-arid regions of northern and central Australia; (ii) crop–livestock systems in the semi-arid zone where livestock graze a mixture of pastures and crops that are often integrated; (iii) high-rainfall, permanent pasture zone in the coastal hinterland and highlands; and (iv) dairy systems covering a broad range of environments and production intensities. A notable trend across these systems has been the decline in sheep numbers and the proportion of income from wool, with beef cattle or sheep meat increasingly important. Although there is evidence that most of these systems have lifted production efficiencies over the past 30 years, total factor productivity growth (i.e. change in output relative to inputs) has failed to match the decline in terms of trade. This has renewed attention on how research and development can help to increase productivity. These industries also face increasing scrutiny to improve their environmental performance and develop sustainable production practices. In order to improve the efficiency and productivity of grassland production systems, we propose and explore in detail a range of practices and innovations that will move systems to new or improved states of productivity or alter efficiency frontiers. These include: filling gaps in the array of pastures available, either through exploring new species or improving the adaptation and agronomic characteristics of species currently sown; overcoming existing and emerging constraints to pasture productivity; improving livestock forage-feed systems; and more precise and lower cost management of grasslands. There is significant scope to capture value from the ecological services that grasslands provide and mitigate greenhouse gas emissions from livestock production. However, large reductions in pasture research scientist numbers (75–95%) over the past 30 years, along with funding limitations, will challenge our ability to realise these potential opportunities.