Grass and Forage Science最新文献

This study investigated the effects of increased dry matter concentration by screw-pressing or wilting and additive application on fermentation quality of primary growth (PG) and first regrowth (ReG) timothy grass. Additionally, the nutritional quality of the liquid produced during the screw-pressing of pre-ensiled and ensiled biomasses was assessed. Two experiments were conducted: PG grass (Experiment 1) was ensiled fresh (Intact) and following liquid extraction via screw-pressing of fresh biomass (Pulp), whilst ReG included wilted biomass in addition to Intact and Pulp (Experiment 2). Biomasses were ensiled without any additives (Control), with lactic acid bacteria inoculant (LAB), or with a formic acid-based additive (FA). The PG biomasses were ensiled in vacuum bags and ReG in laboratory-scale cylindrical silos for 3 months. The silages were subjected to screw-pressing, and the chemical composition of the liquid was analysed. In both experiments, the Pulp had reduced water-soluble carbohydrates and ash compared to the Intact biomass, but crude protein concentration was not affected. In Experiment 2, pulping and wilting improved ensilability. Silages in both experiments exhibited good fermentation quality, with low pH and ammonia nitrogen concentration. Additionally, FA further reduced protein degradation. Wilting restricted silage fermentation, resulting in slightly elevated pH and reduced lactic acid production, alongside decreased ethanol production. Additives improved fermentation quality in different ways; LAB decreased the pH in wilted silages, and FA initiated fibre hydrolysis, leading to an increase in water-soluble carbohydrate concentration, which surpassed levels present in the raw material. In Experiment 2, ensiling increased liquid yield and protein capture into the liquid fraction compared to fresh biomass. Screw-pressing silage treated with LAB increased crude protein concentration in the liquid whilst FA reduced it. Different processing methods demonstrated possibilities to vary feedstock composition for biorefineries, which can be optimised based on the target end products.

Ruminant livestock production is the greatest source of agricultural greenhouse gas (GHG) production, largely due to enteric methane (CH₄) emissions. While the optimised feed rations used in confinement dairy and beef finishing operations can reduce CH₄ emissions of individual animals compared with cattle on forage diets, the profitability of beef cowherds and grazing-based dairies rests on controlling the input costs, most notably feed. Grazing is the least costly feed source, and we have studied the management of non-bloating, nutrient-dense perennial forages with the goal of maximising benefits to ruminants, the environment, producers, and consumers. The naturally alkaline soils, dry climate, long sunny days, and cool nights of the Mountain West United States are favourable for the productivity and persistence of perennial legumes. While alfalfa (Medicago sativa L.) is the highest-value cash crop in the western United States, it is not routinely used for grazing due to the likelihood of bloat. Relative to cattle grazing cool-season grass pastures, cattle grazing sainfoin (Onobrychis viciifolia Scop.), birdsfoot trefoil (Lotus corniculatus L.), and cicer milkvetch (Astragalus cicer L.) had greater intake, production, and lower urinary nitrogen. As a function of intake, the enteric CH₄ emissions of cows, heifers, and calves grazing these legume pastures were reduced 25%–63% compared with the same cattle on grass pastures, and heifers grazing legume pastures had CH₄ emissions no different from heifers on total mixed rations. We integrate these observations of temperate perennial forage legumes and forbs with the wider literature to identify promising traits and species.

This paper evaluates the role of grasslands in a circular food system in Europe by assessing the animal-sourced food and manure production potential of a grass-fed dual-purpose cattle system. A computational model integrated grassland yield estimates, livestock productivity data, and nitrogen balance calculations. Two scenarios, varying in calf fattening duration, were analysed to explore their impacts on livestock numbers, protein production, and nutrient cycling, with the aim of assessing different levels of meat production from grassland. Transitioning to a solely grass-fed dual-purpose cattle system reduces bovine numbers across most European countries. However, despite fewer animals, dual-purpose production can increase bovine protein production in some countries, such as France and Ireland, compared to current levels. This is because dual-purpose cattle produce both milk and meat, with milk providing a higher protein conversion efficiency from grassland than meat. As a result, countries currently producing more meat than milk can partially offset the loss in protein resulting from the reduction in animal numbers. Dual-purpose cattle alone generally cannot meet current animal-sourced protein demands, especially in regions where bovine production depends heavily on concentrate feeds. They may only in some countries provide sufficient animal-sourced food to meet the nationally defined requirements of a healthy diet or generate enough manure to maintain soil fertility without additional nutrient input. Future research should aim to improve the accuracy of grassland yield estimates across Europe and develop context-specific livestock strategies to address these challenges.

Two experiments were carried out to evaluate whether the addition of cellulase and/or xylanase enzymes interacts with regrowth age (RA) in mombasa grass (Megathyrsus maximus) and elephant grass cv. BRS Capiaçu (Cenchrus purpureus) to alter nutritive composition and fermentation profile. Mombasa and elephant grass plots were mowed and harvested at two different RAs (7- and 11-week for mombasa grass; 12- and 16-week for elephant grass). After forages were chopped, they received one of the following additive treatments: no additive (control), xylanase enzyme (300 mg/kg DM; XYL), cellulase enzyme (1 g/kg fresh matter; CEL) and cellulase + xylanase enzymes (same dosages as before; MIX), in a factorial arrangement of 4 (additives) × 2 (regrowth ages), with three replicates. Greater lactic acid and lower acetic acid, butyric acid and NNH₃ concentrations were observed for CEL in mombasa grass silage. Nevertheless, CEL decreased aerobic stability in elephant grass silages and increased effluent production in both species. For mombasa grass silages, lower fermentation loss and more extensive fermentation were observed for early harvest, while the opposite was observed for elephant grass silages. Cellulase improves the fermentation profile of Mombasa grass silage. The combined application of these enzymes does not appear to warrant recommendation. Further research is warranted to evaluate the synergetic effects of cellulase with chemical, absorbent and microbial additives.

Extensive grazing management is an effective strategy to conserve biodiversity. Grazing intensity directly affects sward heterogeneity, resulting in the formation of short and tall vegetation patches, which influence the botanical composition and nutritive value of herbage. Understanding the seasonal dynamics of herbage nutritive value under different grazing intensities is essential to optimise animal performance. Herbage nutritive value data were collected over three years (2019–2021) in the long-term ‘FORBIOBEN’ experiment in Central Germany to analyse the effects of patches, grazing intensity and season. The trial was a one-factorial experiment on grazing intensity in a randomised block design with three replicates, each represented by a one-hectare paddock. Grazing intensities—moderate, lenient and very lenient—were managed based on target compressed sward heights of 6, 12 and 18 cm, respectively. Results show that herbage nutritive value was significantly affected by the patches, sometimes in interaction with season. Short patches contained in general 32.6% higher crude protein and 14.6% lower fibre concentrations than tall patches and also remained seasonally more stable, while in tall patches the phenological development of the plants was ongoing. The higher the grazing intensity the greater was the area covered by short patches per paddock. Thus, when accounting for patch proportions, a higher grazing intensity resulted in significantly improved herbage nutritive value compared to more lenient grazing. To accurately assess herbage nutritive value in areas of extensive grazing management, it is therefore recommended to account for patch-specific variability and to know the patch proportions which result from the grazing intensity.

Multispecific pastures are considered more sustainable to animal production than monocultures. However, studies on mixtures of tropical grasses are underexplored. We aimed to assess whether a mixture of three contrasting growth strategies of perennial tropical forage grasses could outperform their respective monocultures in terms of forage yield and stability. The four treatments included three perennial tropical forage grasses: Andropogon gambagrass (AG; Andropogon gayanus cv. Planaltina), Massai guineagrass [MG; Megathyrsus maximus cv. Massai] and Piatã palisadegrass [PP; Urochloa brizantha cv. BRS Piatã], cultivated as monocultures and as a mixture of the three species. Treatments were randomly assigned to sixteen 180 m² plots and managed intermittently under manual harvest at pre- and post-harvest heights of 35 and 17.5 cm, respectively, for 2 years. The botanical composition of the mixture remained relatively stable, with a predominance of MG (68.9%), followed by PP (20.1%) and AG (6.8%). Annual forage yield varied between years (p = 0.0017) with a difference of 3974 kg DM ha⁻¹ year⁻¹, but not according to treatments (p > 0.05) with an average of 23,012 kg DM ha⁻¹ year⁻¹. No effect was observed for the intra-annual forage yield variance among treatments (p > 0.05). The association among PP, MG and AG in a mixture allows species to coexist with a relatively stable botanical composition, as well as forage yield and stability, similar to their monocultures.

Ensilage consists of the fermentation of sugars to lactic acid independent of the forage by epiphytic microorganisms, lactic acid bacteria (LAB), which vary in number and composition during fermentation. Silage is a means of preserving forage for extended periods of time when fresh forage is limited or seasonally unavailable, and its inadequate fermentation and poor feed management favour the proliferation of pathogens and contribute to silage spoilage. LAB is a group of microorganisms widely distributed in nature, with lactic acid as the main metabolite produced after sugar fermentation. Some LAB produce antimicrobial peptides with low toxicity and proteinaceous nature, known as bacteriocins, which have a broad spectrum of activity against Gram-positive and Gram-negative bacteria, protozoa, fungi, and viruses and can therefore be effective in silage preservation. Among those species, fungal growth leads to nutrient and dry matter losses, reduced palatability, reduced silage intake and consequently reduced animal performance. While laboratory studies provide compelling evidence of their antifungal properties, the practical application of LAB in silage systems must be evaluated with an understanding of the complexities of real-world conditions. LAB inoculants primarily enhance silage quality by driving acidification and promoting a desirable fermentation profile. While bacteriocins can provide an additional layer of microbial control, their efficacy is best realised when combined with proper management practices. This integrated approach ensures that the conditions for optimal fermentation are maintained, allowing LAB to exert their beneficial effects effectively. However, the complexities of silage fermentation necessitate a broader perspective that includes environmental management and forage quality. LAB and bacteriocins are valuable tools, but their success depends on their integration into a comprehensive silage management strategy.