Winter climate change including frequent freeze-thaw episodes and shallow snow cover will have major impacts on the spring regrowth of perennial crops. Non-bloating perennial forage legume species including sainfoin, birdsfoot trefoil, red clover, and alsike clover have been bred for their adaptation to harsh winter conditions. In parallel, the selection of cold-tolerant rhizobial strains could allow earlier symbiotic nitrogen (N) fixation to hasten spring regrowth of legumes.
To identify strains forming nodules rapidly and showing high N-fixing potential, 60 rhizobial strains in association with four temperate legume species were evaluated over 11 weeks under spring soil temperatures for kinetics of nodule formation, nitrogenase activity, and host yield.
Strains differed in their capacity to form efficient nodules on legume hosts over time. Strains showing higher nitrogenase activity were arctic strain N10 with sainfoin and strain L2 with birdsfoot trefoil. For clovers, nitrogenase activity was similar for control and inoculated plants, likely due to formation of effective nodules in controls by endophyte rhizobia present in seeds.
Selection based on nodulation kinetics at low temperature, nitrogenase activity, and yield was effective to identify performant rhizobial strains for legume crops. The use of cold-tolerant strains could help mitigate winter climatic changes.
Tall fescue (Festuca arundinacea [Schreb.], Lolium arundinaceum [Schreb.] Darbysh) and perennial ryegrass (Lolium perenne) are important cool-season forage and amenity grasses that have a mutualistic association with an endophytic fungus. Endophytes confer insect and drought resistance to plants but can produce mammalian toxins. Novel endophytes that do not produce mammalian toxins have been introduced to elite cultivars for commercial production. Seed companies need to maintain adequate levels of novel endophytes within the elite forage cultivars. Endophyte detection is performed using immunochemical and molecular techniques because of their speed and reliability. Early detection in seedlings is essential to evaluate the viability of the endophyte within seed lots.
This research aimed to identify the earliest growth stage in which immunochemical and molecular methods can detect viable endophyte in seedlings of tall fescue cultivars BarOptima (e34), Texoma MaxQII (584), and Jesup MaxQ (542), as well as the perennial ryegrass cultivar Remington (NEA2).
Immunochemical testing detected endophytes in seedlings 14 days after germination (DAG), but the detection rate increased until 42 DAG in some cultivars tested. The molecular marker Tef1exon detected endophytes at a lower rate than the immunochemical method at 28–42 DAG. However, there was insufficient DNA to detect endophytes in 14 DAG seedlings using markers.
We conclude that the most accurate detection of viable endophytes in seedlings was 42 DAG, at which sufficient and consistent endophyte colonization occurred.
Limited information is available regarding the nutritive value and structural characteristics of multispecies swards when rotationally grazed.
Three farmlet types were investigated in terms of their nutritive value: Lolium perenne (LP); L. perenne+Trifolium repens (LP+TR); and a multispecies sward containing grasses, legumes and herbs (MSS). Farmlets were stocked with beef steers (2.5 livestock units ha−1), grazed on a 1 ha scale to 6 cm (MSS) and 4 cm (LP and LP+TR) residuals.
A greater ash concentration was found in MSS than LP (84 vs. 75 g kg−1 DM). Both LP+TR and MSS had higher crude protein and lower neutral detergent fibre concentrations than LP. The relative ranking of water soluble carbohydrate and dry matter (DM) concentration was LP > LP+TR > MSS. Despite the leaf component of the LP farmlet contributing more to herbage DM, the organic matter digestibilities of the swards were similar.
The MSS and LP+TR farmlets achieved similar forage quality under intensive grazing to LP. However, it is worth noting that MSS had a higher concentration of acid detergent lignin, which can negatively impact digestibility. Further investigation is needed to determine optimal grazing management practices that can minimise the effects of higher lignin concentration on digestibility in multispecies swards.
This article represents the perspective of one retired, academic forage breeder and cultivar developer after 50 years of working experience. Developing cultivars that help farmers within pastoral agriculture is the main goal, a system where livestock is the consumer. International Grassland Congress proceedings, as well as the general literature, are historical guides for the state of forage breeding. Efficiency was achieved through technologies; better equipment for planting and harvesting; and advances in computer computation and communication. Biotechnology achievements were fitful and continue to evolve. Cultivar performance mean-reversion, cost to the program, and what the farmer seed buyer was willing to pay are important considerations for applying any technology, especially biotechnologies. Biotech promises were too optimistic. This was due, in part, to a lack of understanding that traditional phenotypic/genotypic field selection programs operate in a complex way with multiple species and several traits screened simultaneously at a modest cost. The majority of current forage cultivars are from field-based selection. Industry participation at scientific conferences declined over time, with less sharing of information the result. Cultivar developers will continue using basic field selection methods but should explore applying any technology; just be clever on when, how, and with whom to use them. Practical advice and experiences are also presented and discussed.
In the Western Highlands of Cameroon (WHC), information on the nutritional value of fodder species consumed by ruminants is very limited.
Through interviews with farmers and monitoring of animals on the range, information was obtained on the types of fodder resources consumed by the ruminants. Samples of each forage species were collected in 15 districts, mixed, chopped, and dried in a ventilated oven at 60°C, and then ground for chemical composition analysis.
Twenty-two forage species were identified. Among these species, Vernonia amygdalina (29.43% ± 0.45% dry matter [DM]) and Pennisetum clandestinum (87.21% ± 1.33% DM) were, respectively, the highest in protein and neutral detergent fiber contents. Manihot esculenta was one of the most energy-rich forages in terms of forage unit for lactation and forage unit for meat production. Hierarchical ascending classification revealed three main groups of forages, respectively, rich in crude fiber (Group 1), protein (Group 2), and energy (Group 3).
The present study identified 22 forage species browsed by ruminants in WHC. Further studies should be carried out to determine the antinutritional factors and to evaluate their nutrient value using in vitro or in situ digestibility techniques.
Grazing prohibition and reduced grazing intensity, as two important “vegetation close-to-nature recovery” methods, have been suggested as economical and effective technologies for enhancing forage production. However, numerous studies have found that the yield of forage could be increased by removing or reducing grazing in a short time in some steady stage of alpine Kobresia meadows, but not in others. To reveal the mechanism behind this phenomenon, we proposed a series of experiments.
We monitored the plant and soil characteristics in the key steady stages of Kobresia meadows under reduced and prohibited grazing conditions in the same geographic and climatic environments in the northeastern Qinghai-Tibet Plateau for 6 years. We estimated the relationships between the plant community and soil nutrients and obtained the following results.
All measured variables were positively correlated with each other. The plant community structure had higher path coefficients to aboveground biomass, soil organic matter, total nitrogen, and nitrate nitrogen than to other factors. The plant community structure played an important role in response to grazing intensity. Different plant functional groups (PFGs) had different responses to grazing intensity, which led to plant community re-establishment or re-organization under different grazing intensities. Poaceae and Kobresia were more sensitive to grazing intensity than other PFGs, and the ratio of Kobresia biomass (including Kobresia humilis and Kobresia pygmaea) to the total biomass of Poaceae and Kobresia could be used as an indicator of regime shifts within plant communities. With Kobresia pygmaea as the dominant species, the prohibition of grazing was not an efficient approach to increase the yield in the steady stages because this treatment needed more time to recover aboveground biomass. If Poaceae is the dominant PFG, grazing should only be prohibited for 3 years in the steady stages because the aboveground biomass will decrease if grazing is prohibited for more than 3 years.
Therefore, the different steady stages of alpine meadows require different recovery methods to increase recovery efficiency and speed.
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