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Accurately monitoring Canopy Nitrogen Concentration (CNC) is a prerequisite for precision nitrogen (N) fertiliser management at the farm scale with carbon and N budgeting across the landscape and ecosystems. While many spectral indices have been proposed for CNC monitoring, their applicability and accuracy are often adversely affected by confounding factors such as aboveground biomass (AGB), crop type, growth stages, and environmental conditions, limiting their broader application and adoption; with AGB being one of the most dominant signals and confounding factors at canopy scale. The confounding effect can become more challenging as AGB is also physiologically linked with CNC across the growth stages. Additionally, the interplay between index form, selection of optimal wavebands and their bandwidths remains poorly understood for CNC index design. This study proposes robust and cost-effective 2- and 4-waveband multispectral (MS) CNC indices applicable across a wide range of crop conditions. We collected 449 canopy reflectance spectra (400–980 nm) together with corresponding CNC and AGB measurements across four growth stages of ryegrass (winter and summer), and five growth stages of barley (winter-spring) in Victoria, Australia, in 2018 and 2019. All possible waveband (400–980 nm) combinations revealed that the best combination varied between seasons and crop types. However, the visible spectrum, particularly the blue region, presented high and consistent performance. Bandwidths of 10–40 nm outperformed either very narrow (2 nm) or very broad bandwidths (80 nm). The newly developed 2-waveband index (416 and 442 nm with 10-nm bandwidth; R2 = 0.75 and NRMSE = 0.2) and 4-waveband index (512, 440, 414 and 588 nm with 40-nm bandwidth; R2 = 0.81 and NRMSE = 0.17) exhibited the best performance, while validation with an independent dataset (from a different growing period to those used in the model development) obtained NRMSE values of 0.25 and 0.24, respectively. The 4-waveband index provides enhanced performance and permits use of broader bandwidths than its 2-waveband counterpart. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a commonly grown pasture species in temperate agriculture, mainly serving as a primary energy source for dairy cows. However, its limited persistence often leads to missed production potential and early resowing, especially in countries that experience summer drought, e.g., Australia and New Zealand. Therefore, understanding the factors influencing perennial ryegrass pasture persistence is crucial for sustainable land management and climate resilience in pasture-based animal production systems. Significant gaps in knowledge exist regarding the factors influencing pasture persistence, as the number of conducted studies in this area remains limited. This study aimed to investigate the factors influencing the expression of persistence in perennial ryegrass populations using airborne and ground-based sensors. A field experiment was conducted in the southwest region of Victoria, Australia, involving ten commercial perennial ryegrass cultivar–endophyte combinations in two different populations. Persistence was evaluated using sensor-based and conventional pasture measurements over two consecutive autumns. The results revealed significant fixed effects of cultivar, endophyte, and environment and their interactions on persistence traits of perennial ryegrass. Cultivars Alto, Samson, and One50 exhibited high levels of persistence when infected with novel endophyte strains. Furthermore, prolonged environmental stresses were found to drive directional selection within pasture populations. The findings emphasise the importance of selecting appropriate cultivar–endophyte combinations and early detection of signs of poor persistence to optimise sward longevity and financial returns from pasture-based animal production systems. This study fills a knowledge gap regarding the factors influencing pasture persistence and provides valuable insights for sustainable pasture management strategies. [ABSTRACT FROM AUTHOR]

In the dairy region of northern Victoria, Australia, the performance of temperate perennial dairy pastures is often poor over summer due to a combination of high temperatures and limited water availability that can restrict dry matter production and plant survival. This review summarizes published and unpublished research on perennial ryegrass, mostly undertaken in the northern Victoria region over the past decade, to help determine its future role in this environment. It includes information from a series of field experiments or case studies where the effects of heat and restricted irrigation on the growth and nutritive characteristics of perennial ryegrass were examined. This research involved investigations on whether plant survival under the stressed experimental conditions could be influenced by plant genotype, irrigation, and grazing management strategies, as well as by the presence of endophyte. In conclusion, it was difficult to identify any irrigation, grazing management or plant genotype effect that consistently improved the performance of perennial ryegrass in the hot, dry summers of northern Victoria, Australia. The incidences of extreme heat events and low water availability in this region are increasing, and the role of C3 perennial grasses as major suppliers of feed for dairy cows is diminishing. A major focus for the dairy industry in this region is now to identify new farming systems and alternative species that may be better adapted to the climate environment than perennial ryegrass, as well as be capable of adapting to year‐to‐year variations in irrigation water supply. [ABSTRACT FROM AUTHOR]

In northern Victoria, Australia, perennial pastures for the dairy industry have historically been based on perennial ryegrass. However, perennial ryegrass does not perform well under high summer temperatures and water stress. We investigated irrigation, renovation and grazing management strategies for improving the resilience and survival of perennial ryegrass over summer on two farms in northern Victoria over 2.5 years. At each farm, two irrigation bays were sown in March 2015. During summer (late December–mid-March), one bay was not irrigated and the other bay received a single mid-summer irrigation. Each bay was sown to 12 ryegrass cultures: five cultivars of perennial ryegrass either oversown or not oversown, and two oversown cultivars of short-lived ryegrass (SLRG). A mid-summer grazing treatment was applied to one-half of each of these plots. All plots at both sites received the same irrigation and grazing management at other times of the year. There were significant variations in dry matter (DM) production, nutritive characteristics and plant frequencies across sites and seasons, and across renovation, irrigation and grazing management strategies. Cumulative DM yields were higher in the perennial ryegrass than the SLRG cultivars. Summer DM removal was very low at both sites; the ungrazed plots recovered and produced more DM in the following cooler period than the grazed plots in the first year but not the second. Metabolisable energy concentration was higher for perennial ryegrass than SLRG cultivars and was also higher in plots that had been grazed over the summer. There were large differences in plant frequency between species, and there were some differences among perennial ryegrass cultivars. The effect of summer grazing on plant frequency varied at each site and was not significant within an irrigation treatment. This research confirms that perennial ryegrass is not well suited to the hot, dry summers of northern Victoria and suggests that, under conditions of limited summer irrigation, farmers should focus on plant survival rather than summer yield if they are to maximise annual DM production. The effects of restricted irrigation and summer grazing were examined in plots of perennial and short-lived ryegrass cultivars at two district sites in northern Victoria, Australia. Responses varied across sites, seasons and cultures. Perennial ryegrasses performed better than short-lived ryegrasses, but dry matter production was low and plant frequency was a better indicator of plant resilience to these conditions. [ABSTRACT FROM AUTHOR]

Context: Economic modelling identified that mating of ewe lambs for lambing at 1 year of age has the potential to increase the profitability of sheep-production systems in south-western Victoria. In order to optimise reproductive rates, ewe lambs should weigh at least 35–40 kg, have a condition score (CS) of 3.0 at mating, and be gaining weight (100–150 g/day) during mating. However, typical perennial ryegrass (Lolium perenne L.) pastures in south-west Victoria do not support the attainment of these targets without additional supplementation. Aim: Our research aimed to determine how grazing summer-active pastures or brassica (Brassica napus L.) forages affects the liveweight, CS, conception and reproductive rate of ewe lambs when offered before and during mating compared with a system using perennial ryegrass plus supplement. Methods: A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in a complete block design. The treatments were: canola (B. napus , two treatments of different cultivars), forage brassica, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass. Key results: Ewe lambs grazing canola or forage brassica had higher (P < 0.05) liveweight gains during the pre-mating and mating periods than those grazing the perennial ryegrass treatment (148 vs 75 g/day in 2014, s.e.m. 17; 139 vs 54 g/day in 2016, s.e.m. 17). In 2014, spring-sown dual-purpose canola, lucerne and chicory resulted in higher (P < 0.05) reproductive rates (144–151%) than the perennial ryegrass treatment (103%); forage brassica and plantain gave intermediate results (128% and 129%). Conclusion: Brassica forages (including spring-sown canola), lucerne and chicory can support the attainment of key liveweight and CS targets for successful mating of ewe lambs in autumn. Implications: Spring-sown canola is therefore a viable alternative forage for use by livestock producers in southern Australia and presents an opportunity to incorporate an alternative income stream in mixed-farming systems. Mating of ewe lambs for lambing at 1 year of age has the potential to increase the profitability of sheep-production systems; however, successful mating of ewe lambs requires that they have reached a bodyweight of 35–40 kg, have a condition score of at least 3.0, and be gaining weight before and during mating. Grazing dual-purpose canola crops during summer and autumn enables ewe lambs to meet these targets and improves liveweight gains and reproductive performance relative to traditional perennial ryegrass pastures. The implications are a more productive ewe flock, and a flock that produces more lambs over the duration of a ewe's lifetime. [ABSTRACT FROM AUTHOR]

Context: Filling the summer–autumn feed gap is a key priority for sheep producers in southern Australia's high-rainfall zone. Aim: Our research aimed to determine whether spring-sown winter-type canola (Brassica napus L.) could increase herbage mass and nutritive characteristics during summer and autumn relative to other forage options in southern Australia's HRZ. Methods: A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in the complete block design. The treatments were: canola (two treatments of different cultivars), forage brassica (B. napus), lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass (Lolium perenne L.). Key results: Herbage mass and nutritive characteristics of the canola varieties did not differ (P > 0.05) from forage brassica. Herbage mass in March 2014 was 3.35–3.64 t dry matter (DM)/ha for brassicas; 1.05–1.37 t DM/ha for perennial ryegrass, plantain and chicory; and 2.94 t DM/ha for lucerne (P < 0.001, l.s.d. = 1.20). In March 2016, herbage mass was 1.86–2.05 t DM/ha for brassicas and 2.14–2.49 for the other forage treatments (P < 0.05; l.s.d. = 0.47). Brassicas had higher (P < 0.05) metabolisable energy (ME) concentrations and lower (P < 0.05) neutral detergent fibre (NDF) concentrations on most sampling dates than chicory, plantain, lucerne and perennial ryegrass. The crude protein (CP) concentration of the brassica treatments was not different (P > 0.05) from that of the other forage treatments. Concentrations of ME, CP and NDF were very similar between years for the brassicas, with March ME, CP and NDF concentrations of 12.0–13.2 MJ/kg DM, 14.0–20.1% DM and 16.7–23.6% DM. Conclusion: Canola provided increased or equivalent levels of herbage mass and nutritive characteristics compared with other forage options in south-western Victoria on most, but not all, sampling dates. However, the annual spring-sowing requirement is a challenge under variable spring-rainfall conditions and may limit productivity if there is poor establishment. Implications: Spring-sown canola is a viable alternative forage for livestock producers and offers a potential second income stream in high-rainfall-zone livestock farming systems. Filling the summer–autumn feed gap is a key priority for sheep producers in southern Australia's high-rainfall zone, with summer and autumn traditionally being a time of feed shortage for livestock production. Winter-type canola can produce up to 3.5 t/ha of high-quality feed for grazing livestock during this key summer–autumn period. This provides livestock producers with the opportunity to increase production during this time of year, which could involve finishing livestock to higher slaughter weights or increasing the reproductive performance of ewes, utilising forage rather than purchasing supplementary feeds. [ABSTRACT FROM AUTHOR]

Context: The Australian dairy industry is characterised by pasture-based feeding systems, where grazed pasture is commonly supplemented with cereal grain to increase milk production of dairy cows. Perennial ryegrass (PRG; Lolium perenne L.) is the most commonly used pasture species, with a wide range of cultivars available. However, the nutritive characteristics and the degradation of nutrients in individual PRG cultivars grown in different environments in Australia are unknown, and significant variation between cultivars may impact on supplementary nutrient requirements. Aims: The objective of this experiment was to quantify the extent of ruminal degradation of nutrients in three contrasting PRG cultivars (Bealey NEA2, Trojan NEA2 and Victorian SE) harvested during early spring and summer from Gippsland, northern Victoria and south-west Victoria in Victoria, Australia. Methods: Degradation parameters were determined by in situ incubation in the rumens of non-lactating, rumen-fistulated Holstein–Friesian cows for 72 h using a nylon bag technique. Key results: During both seasons, Bealey NEA2 had the greatest effective degradability of crude protein and neutral detergent fibre compared with Trojan NEA2 and Victorian SE. Cultivars harvested during early spring had greater effective degradability of crude protein and neutral detergent fibre, and a greater amount of rumen degradable protein compared with cultivars harvested during summer. Cultivars harvested from Gippsland had greater crude protein and neutral detergent fibre effective degradability, as well as a greater amount of rumen degradable protein, whereas cultivars harvested from northern Victoria had a greater amount of undegraded dietary protein. Conclusions: These results demonstrate that the ruminal degradation of PRG cultivars declines with increasing maturity, and that there are differences between cultivars and regions; however, differences between seasons are of a greater magnitude and are more important to consider when formulating optimal supplementary grain rations. Implications: This research has positive implications for farmers who will be able to understand the degradation of nutrients in PRG, and the amounts of rumen degradable protein and undegraded dietary protein available from pasture during each season. Farmers will be able to use this information to formulate supplementary grain rations that complement the nutrients from pasture and optimise milk production. Dairy production in south-eastern Australia is based on pasture-based feeding systems, where perennial ryegrass is the most common pasture species grown. This research provides novel information on the degradation characteristics of perennial ryegrass cultivars grown on farms in Australia, with degradability decreasing as the pasture matures. This will help farmers to formulate supplementary grain rations to match nutrient supply from pasture. [ABSTRACT FROM AUTHOR]

Improvement in nutritive characteristics resulting from breeding perennial ryegrass (PRG) cultivars used in Australia from the 1970s to the present day was quantified in a grazed field experiment in south-western Victoria. The experiment was sown in May 2014 with measurements undertaken over 3 years. The experiment contained 36 PRG treatments (cultivar–endophyte combinations), which were replicated four times, with herbage nutritive characteristics measured at each grazing. The treatments differed in estimated metabolisable energy (ME), crude protein and neutral detergent fibre (NDF) concentrations at each harvest date. The decade of cultivar release had little effect on the ME or the NDF concentration of the cultivars released from 1970s onward. Early season diploids had a lower ME concentration than did later-maturing diploid cultivars (11.0 vs 11.4 MJ/kg DM), predominantly due to a lower ME concentration in late spring and early summer (10.3 vs 11.1 MJ/kg DM). The tetraploid cultivars had a higher ME concentration (11.8 vs 11.4 MJ/kg DM) and a lower NDF (480 vs 505 g/kg DM) concentration than did the mid- and late-season diploid cultivars. These differences are likely to be of economic importance at the farm level. The genetic gain in nutritive characteristics of perennial ryegrass cultivars has not been quantified in dairy environments in Victoria. This work aimed to quantify these improvements, but found that most cultivar differences could be attributed to cultivar maturity and ploidy factors, with little effect of the decade of release. These cultivar differences are likely to be of economic importance at the farm level. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is the predominant perennial forage species used in temperate irrigated dairy-production systems in Australia. However, when temperatures are high, even with optimal irrigation strategies and nutrient inputs, dry matter (DM) production can be compromised. This research investigated the effects of perennial ryegrass and tall fescue genotypes and summer irrigation on (DM) production and survival. Ten perennial ryegrass cultivars, three hybrid ryegrasses and two cultivars of tall fescue (Festuca arundinacea (Schreb) Darbysh.) were sown in northern Victoria, Australia, in May 2014, and were managed under full irrigation or restricted irrigation (no irrigation between late December and mid-March) over a 3-year period. Measurements included net pasture accumulation (DM production), sward density (plant frequency) and water-soluble carbohydrate concentration. Apart from the expected differences in DM yield over the summer period between full irrigation and restricted irrigation, there were few differences in DM production among perennial ryegrass or tall fescue cultivars. Plant frequency declined significantly under restricted irrigation in Years 2 and 3 compared with full irrigation but there were no differences among perennial ryegrass cultivars. In Year 2, plant frequency was higher in the tall fescue cultivars than the ryegrass cultivars. The recovery pattern in DM production following recommencement of irrigation in mid-March (autumn) varied across years. In Year 1, plants recovered rapidly once irrigation recommenced in autumn. However, in Years 2 and 3, autumn and winter pasture accumulation under restricted irrigation was 30–35% less than under full irrigation. These differences were possibly related to decreases in plant frequency, as well as to differences in the amounts of residual pasture mass (or carbohydrate reserves) present when growth ceased. Analyses of the water-soluble carbohydrate concentrations in the pseudostem during summer and autumn in Year 3 showed differences in total water-soluble carbohydrate and in fructan and sucrose concentrations between irrigation treatments but no consistent differences among genotypes. Perennial ryegrass is the predominant perennial forage species in temperate irrigated dairy systems in Australia; however, its summer production can be poor. This research investigated the effects of genotype and summer irrigation on growth and survival of 15 perennial ryegrass and tall fescue genotypes. Dry matter production and plant frequency were reduced under restricted irrigation and there were few differences among cultivars, suggesting that plant performance over summer may be more influenced by irrigation management than by cultivar selection. [ABSTRACT FROM AUTHOR]

A 3-year experiment compared the effects of wild-type ryegrass endophyte and two novel endophytes on milk production in dairy cattle. On three 9.9-ha farmlets in West Gippsland, Victoria, pasture swards were established that were dominant in perennial ryegrass (Lolium perenne) infected with either wild-type, AR1 or AR37 endophytes. Each farmlet was stocked with 25 spring-calving Holstein-Friesian cows, which rotationally grazed nine paddocks within their farmlet during three lactations over 3 years. The three endophytes are known to produce different alkaloids, with wild-type producing ergot alkaloids, lolitrems and peramine, AR1 producing peramine and AR37 producing epoxy-janthitrems. These alkaloids were present in fresh pasture as well as hay and silage made from that pasture. Grazed pasture comprised 53% of estimated annual DM intake. The proportion was least from December to March when the daily ration of 2 kg DM/cow.day cereal grain was increased to 6 kg/day and forage supplements were fed consisting of purchased lucerne (Medicago sativa) hay and pasture silage grown on the farmlets. There were no differences in pasture accumulation rates or nutritive characteristics of ryegrass pastures on the three farmlets and no differences in the production of milk, fat or protein by cows grazing pasture infected with the three endophytes. Ryegrass staggers was only observed in four cows consuming the wild-type-infected ryegrass in the first year when the highest concentrations of lolitrem B were recorded in pasture. Soil samples showed lower numbers of root aphids (Aploneura lentisci), mealybugs (Pseudococcidae) and pasture tunnel moths (Philobota spp.) beneath ryegrass infected with the AR37 endophyte compared with the other two endophytes. Numbers of redheaded (Adoryphorus couloni) and blackheaded (Aphodius tasmaniae) cockchafers did not differ between treatments. Under dairy management and supplementary feeding regimes common to south-eastern Australia, the novel endophytes AR1 and AR37 had no effect on the milk production compared with the wild-type endophyte, and did not cause ryegrass staggers. A 3-year grazing experiment compared the effects of wild-type ryegrass endophyte and two novel endophytes (AR1 and AR37), on milk production from dairy cows. Under dairy management and supplementary feeding regimes common to south-eastern Australia, the novel endophytes had no effect on the milk production compared with the wild-type endophyte, and did not cause ryegrass staggers. Pasture growth rates and incidence of redheaded and blackheaded cockchafers were not different under the three endophyte treatments. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf virus (BYDV) was detected in perennial ryegrass cultivars examined from three sites in south-western Victoria (Balmoral, Mininera and Hamilton); the frequency of BYDV infection varied with cultivar. PAV-related isolates were prevalent at all sites, but the incidence of MAV- and RPV-related isolates varied with the site and cultivar. The PAV-related isolate was less frequent in cv. Ellett than in cv. Victorian at all sites. The implications for the epidemiology of the disease and its agronomic importance in Victoria are discussed. [ABSTRACT FROM AUTHOR]