Artykuły w czasopismach: „Grazing resistance”

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Lürling, Miquel. "Grazing resistance in phytoplankton". Hydrobiologia 848, nr 1 (11.08.2020): 237–49. http://dx.doi.org/10.1007/s10750-020-04370-3.

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AbstractPhytoplankton is confronted with a variable assemblage of zooplankton grazers that create a strong selection pressure for traits that reduce mortality. Phytoplankton is, however, also challenged to remain suspended and to acquire sufficient resources for growth. Consequently, phytoplanktic organisms have evolved a variety of strategies to survive in a variable environment. An overview is presented of the various phytoplankton defense strategies, and costs and benefits of phytoplankton defenses with a zooming in on grazer-induced colony formation. The trade-off between phytoplankton competitive abilities and defenses against grazing favor adaptive trait changes—rapid evolution and phenotypic plasticity—that have the potential to influence population and community dynamics, as exemplified by controlled chemostat experiments. An interspecific defense–growth trade-off could explain seasonal shifts in the species composition of an in situ phytoplankton community yielding defense and growth rate as key traits of the phytoplankton. The importance of grazing and protection against grazing in shaping the phytoplankton community structure should not be underestimated. The trade-offs between nutrient acquisition, remaining suspended, and grazing resistance generate the dynamic phytoplankton community composition.

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Moore, Peter D. "Evolutionary ecology: Toxins and grazing resistance". Nature 324, nr 6096 (grudzień 1986): 410. http://dx.doi.org/10.1038/324410a0.

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van Donk, Ellen, i Dag O. Hessen. "Grazing resistance in nutrient-stressed phytoplankton". Oecologia 93, nr 4 (kwiecień 1993): 508–11. http://dx.doi.org/10.1007/bf00328958.

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Benot, Marie-Lise, Cendrine Mony, Jan Lepš, Laurent Penet i Anne Bonis. "Are clonal traits and their response to defoliation good predictors of grazing resistance?" Botany 91, nr 2 (luty 2013): 62–68. http://dx.doi.org/10.1139/cjb-2012-0100.

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Grazing resistance in plants, which can be defined as the ability to grow and reproduce under grazed conditions, is either associated to defoliation avoidance or tolerance. Clonal traits are often neglected when studying functional responses to grazing, despite frequent occurrence in grassland vegetation. We investigated whether clonal traits and response to defoliation were associated to increased grazing resistance. First, grazing resistance was estimated for eight clonal species using abundance patterns in a long-term field study. We then analysed its correlation with traits in undisturbed conditions and responses to defoliation in a garden experiment. A few traits were correlated to grazing resistance, though only one was a clonal trait (belowground clonal biomass). Grazing resistance was negatively correlated to shoot height and belowground clonal biomass and positively correlated to inflorescence biomass, suggesting that tall rhizomatous species investing little in sexual reproduction were at a disadvantage under grazed conditions. Both shoot height and belowground clonal biomass were negatively affected by defoliation but their decrease was significantly less for species that expressed the greatest grazing resistance in the field. Our findings show that incorporating clonal traits slightly improved predictions about field grazing resistance in the eight investigated species.

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Liebig, M. A., J. R. Hendrickson, J. D. Berdahl i J. F. Karn. "Soil resistance under grazed intermediate wheatgrass". Canadian Journal of Soil Science 88, nr 5 (1.11.2008): 833–36. http://dx.doi.org/10.4141/cjss08016.

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Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey subsp. intermedium] is a productive, high-quality perennial forage that lacks persistence under grazing. A study was conducted to evaluate the effects of three grazing times on soil bulk density, soil pH, and soil organic C under intermediate wheatgrass. Treatment effects on the three soil attributes were negligible, implying grazing time did not negatively impact intermediate wheatgrass beyond a threshold whereby critical soil functions were impaired. Findings from this study are important in the context of sustainable forage and cropping system management, where maintaining or improving critical soil functions are essential for enhancing agroecosystem sustainability. Key words: Seeded perennial forages, Northern Great Plains, soil organic C

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NAETH, M. A., D. J. PLUTH, D. S. CHANASYK, A. W. BAILEY i A. W. FEDKENHEUER. "SOIL COMPACTING IMPACTS OF GRAZING IN MIXED PRAIRIE AND FESCUE GRASSLAND ECOSYSTEMS OF ALBERTA". Canadian Journal of Soil Science 70, nr 2 (1.05.1990): 157–67. http://dx.doi.org/10.4141/cjss90-018.

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The impacts of long-term grazing on compaction were assessed in mixed prairie and fescue grassland ecosystems of Alberta. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Bulk density was measured with a surface moisture/density gauge and a combination moisture/density probe to 65 cm. Penetration resistance to 30 cm was measured with a cone penetrometer. Solonetzic soils were less sensitive to compaction under grazing than Chernozemic soils. Heavy intensity and/or early season grazing had greater impacts on compaction than light intensity and/or late season grazing. Under the former grazing regimes, bulk density increased to 7.5 cm at Kinsella and 65 cm at Stavely; penetration resistance increased to depths of 2.5 cm at Brooks, 15 cm at Kinsella, and 30 cm at Stavely. Heavy trampling versus regular grazing increased penetration resistance to depths of 30 and 10 cm under heavy intensity and/or early season and light intensity and/or late season grazing, respectively. Late season grazing at Brooks and light to moderate grazing at Stavely may be used as management models to reduce compaction under grazing. Trends were not as clear at Kinsella, but light June and autumn grazing had the least compacting effect. Key words: Compaction, grazing, rangelands, penetration resistance, bulk density

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Tarao, Mitsunori, Jan Jezbera i Martin W. Hahn. "Involvement of Cell Surface Structures in Size-Independent Grazing Resistance of Freshwater Actinobacteria". Applied and Environmental Microbiology 75, nr 14 (5.06.2009): 4720–26. http://dx.doi.org/10.1128/aem.00251-09.

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ABSTRACT We compared the influences of grazing by the bacterivorous nanoflagellate Poterioochromonas sp. strain DS on ultramicrobacterial Actinobacteria affiliated with the Luna-2 cluster and ultramicrobacterial Betaproteobacteria of the species Polynucleobacter cosmopolitanus. These bacteria were almost identical in size (<0.1 μm3) and shape. Predation on a Polynucleobacter strain resulted in a reduction of >86% relative to the initial bacterial cell numbers within 20 days, while in comparable predation experiments with nine actinobacterial strains, no significant decrease of cell numbers by predation was observed over the period of ≥39 days. The differences in predation mortality between the actinobacterial strains and the Polynucleobacter strain clearly demonstrated size-independent grazing resistance for the investigated Actinobacteria. Importantly, this size-independent grazing resistance is shared by all nine investigated Luna-2 strains and thus represents a group-specific trait. We investigated if an S-layer, previously observed in an ultrastructure study, was responsible for the grazing resistance of these strains. Experiments aiming for removal of the S-layer or modification of cell surface proteins of one of the grazing-resistant strains by treatment with lithium chloride, EDTA, or formaldehyde resulted in 4.2- to 5.2-fold higher grazing rates in comparison to the levels for untreated cells. These results indicate the protective role of a proteinaceous cell surface structure in the size-independent grazing resistance of the actinobacterial Luna-2 strains, which can be regarded as a group-specific trait.

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Rodd, A. V., Y. A. Papadopoulos, L. F. Laflamme, K. B. McRae, S. A. E. Fillmore i R. W. Wilson. "Effect of rotational grazing on selected physical properties of a Gleyed Brunisolic Gray Luvisol loam in Nova Scotia". Canadian Journal of Soil Science 79, nr 1 (1.02.1999): 117–25. http://dx.doi.org/10.4141/s97-094.

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Low organic matter content and weak soil structure, combined with high annual precipitation, make the soils of the Maritime Provinces extremely susceptible to compaction. Although many pasture studies have been conducted in the Maritime Provinces, none has investigated the impact of pasturing cattle on soil physical properties. Soil properties such as resistance to penetration, bulk density and hydraulic conductivity were monitored on pasture swards receiving various rotational-grazing intensities. These parameters were measured concomitantly on traffic-free areas that had been harvested as conserved forage. Resistance to penetration measurements indicate that a significant amount of compaction by cattle occurred during the 1990, 1991 and 1992 grazing seasons. Penetration resistance was generally greatest in the top 6 cm of soil, but was alleviated by frost action during the subsequent winter and spring. The other soil parameters measured were either more variable (surface and subsurface saturated hydraulic conductivity) or less sensitive (bulk density) to compaction. Although more variable, surface hydraulic conductivity was significantly higher in the traffic-free conserved forage areas than in the pasture paddocks. Rest intervals between grazings had no significant effect on saturated hydraulic conductivity. Seasonal change in resistance to penetration generally increased as rest interval decreased. The timothy/alfalfa swards (little alfalfa was left in the pastures by 1992) had the least seasonal change in resistance to penetration. Key words: Cattle, compaction, resistance to penetration, bulk density, hydraulic conductivity

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Chanasyk, David S., i M. Anne Naeth. "Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada". Canadian Journal of Soil Science 75, nr 4 (1.11.1995): 551–57. http://dx.doi.org/10.4141/cjss95-078.

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Alberta foothills fescue grasslands are very productive ecosystems but there is concern that the traditional season-long (continuous) grazing regimes may be leading to soil deterioration due to compaction and increased soil strength. The objectives of this study were to quantify grazing effects on soil bulk density and soil strength of sloped areas in the Alberta foothills fescue grasslands at the Agriculture Canada Stavely Range Substation. The effects of two grazing intensities (heavy and very heavy) for two treatments (short duration and continuous) on these two parameters were compared to an ungrazed control. Soil bulk density and soil water to a depth of 7.5 cm were measured with a surface water/density gauge. Soil strength was measured with a hand-pushed cone penetrometer to a depth of 45 cm. Cone index, the maximum penetration resistance in a given depth interval, was used as a measurement parameter for soil strength.Grazing affected both soil bulk density and penetration resistance. Even short-duration treatments affected these soil properties, although their effects were similar for both heavy and very heavy grazing intensities. Distinction between heavy and very heavy continuous grazing treatments was clear for both bulk density and penetration resistance, with the very heavy treatment having the greatest detrimental effect on these two soil parameters for all treatments. Bulk density and soil strength values were always lowest in the spring after snowmelt and highest late in the growing season, reflecting the water status of these ecosystems. Identical treatment rankings were obtained using bulk density and penetration resistance, but cone index was a more sensitive indicator of the effects of grazing than bulk density. Key words: Grazing, fescue grasslands, bulk density, soil strength

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Kornele, Michelle L., Melanie J. McLean, Anna E. O'Brien i Aimée M. Phillippi-Taylor. "Antiparasitic resistance and grazing livestock in the United States". Journal of the American Veterinary Medical Association 244, nr 9 (maj 2014): 1020–22. http://dx.doi.org/10.2460/javma.244.9.1020.

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Pajdak-Stós, Agnieszka, Edyta Fiałkowska, Janusz Fyda i Roman Babko. "Resistance of nitrifiers inhabiting activated sludge to ciliate grazing". Water Science and Technology 61, nr 3 (1.02.2010): 573–80. http://dx.doi.org/10.2166/wst.2010.868.

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We monitored the succession of nitrifiers in a ne.wly opened wastewater treatment plant for five weeks. After the first distinct decrease in total nitrogen, we began monitoring the appearance, size and number of nitrifying bacteria colonies using the fluorescence in situ hybridization (FISH) method. Ammonia oxidizing bacteria (AOB) colonies were visualized under green excitation as red, and nitrite oxidizing bacteria (NOB) colonies were visualized under blue excitation as green. The changes in protozoan community were monitored simultaneously. Ciliates were divided into four functional groups: predatory, bacterivorous free-swimming, bacterivorous crawling, and sessile. The results showed that at the time of the first distinct total nitrogen decrease, the mean length of both AOB and NOB were relatively low, but the colonies, especially those of nitrite oxidizers, were abundant. In time, the distribution of ammonia oxidizer colonies shifted towards larger sizes, but their quantity decreased. In the case of nitrite oxidizers, a similar trend was noticeable but less pronounced. These changes corresponded with an increasing number of crawling bacterivorous ciliates dominated by the “scavenger” genus Aspidisca. The increasing size of nitrifier colonies may have been due to the growing grazing pressure from crawling bacterivorous ciliates. The strong grazing pressure did not negatively affect N-NH4+ removal effectiveness.

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Griffiths, Wendy M., i Iain J. Gordon. "Sward structural resistance and biting effort in grazing ruminants". Animal Research 52, nr 2 (marzec 2003): 145–60. http://dx.doi.org/10.1051/animres:2003012.

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Oom, Sander P., Alison J. Hester i Colin J. Legg. "Grazing across grass:shrub boundaries: Can spatial heterogeneity increase resistance?" Agriculture, Ecosystems & Environment 139, nr 1-2 (15.10.2010): 159–66. http://dx.doi.org/10.1016/j.agee.2010.07.014.

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Mapfumo, E., D. S. Chanasyk, M. A. Naeth i V. S. Baron. "Soil compaction under grazing of annual and perennial forages". Canadian Journal of Soil Science 79, nr 1 (1.02.1999): 191–99. http://dx.doi.org/10.4141/s97-100.

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This study investigated the impact of heavy, medium and light grazing of meadow bromegrass an triticale on soil bulk density, relative compaction and penetration resistance. The study was conducted at Lacombe, Alberta, on a Orthic Black Chernozem of loam to silt loam texture. Sampling was conducted in fall 1995, spring 1996, fall 1996 and spring 1997. Core samples to a 15-cm depth were collected for measurement of bulk density and moisture content. Penetration resistance to 15 cm was measured with a hand-pushed cone penetrometer. The standard Proctor test was used to determine maximum bulk density. Relative compaction was the ratio of actual bulk density to the Proctor maximum bulk density expressed as a percentage. Surface (0–2.5 cm) bulk density and penetration resistance were significantly greater under heavily grazed than under medium and lightly grazed meadow bromegrass only for fall 1995. Differences in bulk density, relative compaction and penetration resistance for different grazing intensities in spring and fall 1996 and spring 1997 were either small or not significant. Generally, bulk density decreased over winter in the top 2.5 cm, was not consistent in the 5- to 10-cm depth interval and did not change in the 10- to 15-cm interval. Except in fall 1995, the relative compaction values for all grazing intensities and forage species were less than 90%, a value considered critical for plant growth. Generally, within each grazing level, there were minimal differences in bulk density, relative compaction and penetration resistance under triticale compared to those under meadow bromegrass. Key words: Bulk density, relative compaction, penetration resistance

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Lodge, GM. "Management practices and other factors contributing to the decline in persistence of grazed lucerne in temperate Australia: a review". Australian Journal of Experimental Agriculture 31, nr 5 (1991): 713. http://dx.doi.org/10.1071/ea9910713.

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The literature relevant to the grazing management of lucerne in temperate Australia is reviewed with emphasis on the factors likely to affect its persistence. Knowledge of lucerne physiology is used to question the validity of the traditional methods of managing grazed stands, which rely mainly on using 10% flowering as a guide to root carbohydrate levels. From these data several alternative management guidelines are proposed that may lead to increased persistence; however, for long-term persistence, there is little doubt that lucerne needs to be grazed leniently and at a late stage of maturity. Several grazing experiments indicate that grazing periods of 16-20 days should have no effect on persistence, provided that the rest period between successive grazings is 35 days or longer. Data from other countries and Australian data from a limited number of experiments also indicate that grazing in either autumn or winter may substantially reduce production and could affect persistence. Three grazing studies in New South Wales were used to highlight critical differences in experimental design which make comparisons among experiments difficult. Standardised sowing rates and grazing management, and statistical procedures which account for the genotype x management x environment interaction, are suggested to improve the extrapolation of results from experiments to other environments. Persistence of different lucerne types under grazing, particularly those recently imported from the U.S.A. or bred in Australia, is considered. While it has been proposed that grazing effects may be related to crown structure, interactions with other factors which affect persistence may also occur. If grazing can be considered to be stressful to a lucerne plant then it could interact with other stresses, caused by moisture deficit, excessive moisture, insect pests and disease, to reduce persistence. Additionally, considerable variation in varietal resistance to some pests and diseases has been recorded in haycut stands, and so there may also be cultivar x grazing effects. All of these factors could combine to affect the persistence of a particular cultivar under grazing. Patterns of lucerne decline were either continuous or step-like. Continuous decline was associated with prolonged grazing, grazing and moisture stress, grazing under waterlogged conditions, or grazing in situations where the incidence of disease was likely to be high. To understand the reasons why plants fail to persist, measurements need to be made frequently and a1 regular intervals, and the moisture and disease status of the site needs to be accurately monitored. The adequacy of different methods of measuring stand persistence is also questioned. The implications for graziers, researchers and lucerne breeders are discussed.

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Krzic, Maja, Sarah F. Lamagna, Reg F. Newman, Gary Bradfield i Brian M. Wallace. "Long-term grazing effects on rough fescue grassland soils in southern British Columbia". Canadian Journal of Soil Science 94, nr 3 (sierpień 2014): 337–45. http://dx.doi.org/10.4141/cjss2013-019.

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Krzic, M., Lamagna, S. F., Newman, R. F., Bradfield, G. and Wallace, B. M. 2014. Long-term grazing effects on rough fescue grassland soils in southern British Columbia. Can. J. Soil Sci. 94: 337–345. Rough fescue (Festuca campestris Rydb.) is a highly palatable forage species with little resistance to continuous grazing. The objective of this study was to evaluate the effects of long-term cattle grazing on soil properties, above-ground biomass, and canopy cover of key grass species on rough fescue grasslands in the southern interior British Columbia. Soil and vegetation properties were determined on a total of six open grassland sites located at the Lac du Bois and Hamilton Mountain. At all sites, grazing use has decreased over time, with the heaviest grazing occurring prior to 1960. The long-term (25–75 yr) elimination of grazing on these semi-arid grasslands has led to greater above-ground biomass and canopy cover of rough fescue, as well as increased soil polysaccharides; however, no differences in total soil C, N, and aggregate stability were found between pastures with and without grazing. Both soil bulk density and mechanical resistance were greater on grazed plots compared with those without grazing, with differences being more pronounced at the Hamilton Mountain location. The current grazing regime has not allowed for the elimination of negative effects of overgrazing on soil compaction on these rough fescue grasslands, especially at the location that continued to be grazed more heavily (i.e., Hamilton Mountain). Our findings suggest that soils in these grazing-sensitive grasslands need more than 75 yr to fully recover from the impacts of overgrazing.

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van den Honert, Michaela Sannettha, Pieter Andries Gouws i Louwrens Christiaan Hoffman. "Escherichia coli Antibiotic Resistance Patterns from Co-Grazing and Non-Co-Grazing Livestock and Wildlife Species from Two Farms in the Western Cape, South Africa". Antibiotics 10, nr 6 (22.05.2021): 618. http://dx.doi.org/10.3390/antibiotics10060618.

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Although limited, studies have found conflicting results on whether co-grazing results in significant antibiotic resistance transfer between species. This type of farming system can act as a vector in the geographical spread of antibiotic-resistant bacteria in the environment. The aim of this study was to determine the antibiotic-resistant patterns between co-grazing and non-co-grazing livestock and wildlife species in South Africa. Escherichia coli was isolated from the faeces of various wildlife and livestock species from two farms in South Africa and was tested for antibiotic resistance using the Kirby–Bauer disk diffusion method against chloramphenicol, nalidixic acid, ampicillin, streptomycin, sulphafurazole, and tetracycline. A selection of some common antibiotic-resistant genes (blaCMY, aadA1, sul1, sul2, tetA, and tetB) were detected using PCR. The E. coli isolates from wildlife and livestock that co-grazed showed no significant differences in antibiotic resistance patterns. However, this was not the case for tetracycline resistance as the livestock isolates were significantly more resistant than the co-grazing wildlife isolates. The E. coli isolates from the non-co-grazing livestock and wildlife had significant differences in their antibiotic susceptibility patterns; the wildlife E. coli isolates were significantly more resistant to sulphafurazole and streptomycin than the livestock isolates, whilst those isolated from the cattle were significantly more resistant to ampicillin than the wildlife and sheep isolates. The results of this study suggest that there could be an exchange of antibiotic-resistant bacteria and genes between livestock and wildlife that co-graze.

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Neilly, Heather, Eric J. Nordberg, Jeremy VanDerWal i Lin Schwarzkopf. "Arboreality increases reptile community resistance to disturbance from livestock grazing". Journal of Applied Ecology 55, nr 2 (7.09.2017): 786–99. http://dx.doi.org/10.1111/1365-2664.12982.

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Evans, C. R. W., M. Krzic, K. Broersma i D. J. Thompson. "Long-term grazing effects on grassland soil properties in southern British Columbia". Canadian Journal of Soil Science 92, nr 4 (maj 2012): 685–93. http://dx.doi.org/10.4141/cjss2011-070.

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Evans, C. R. W., Krzic, M., Broersma, K. and Thompson, D. J. 2012. Long-term grazing effects on grassland soil properties in southern British Columbia. Can. J. Soil Sci. 92: 685–693. Although grazing effects on soil properties have been evaluated on various temperate grasslands, no study has dealt with these effects in the southern interior of British Columbia. The objective of this study was to determine the effects of spring versus fall season grazing as well as grazing [at a moderate rate of 0.6 animal unit months (AUM) ha−1] versus non-grazing by beef cattle on selected soil properties. Effects were determined 20 and 30 yr after the establishment of the field experiment. Soil properties were determined for the 0- to 7.5-cm, 7.5- to 15-cm, and 15- to 30-cm depths. In comparison with fall grazing, spring grazing had greater soil bulk density, greater mechanical resistance within the top 15 cm of the soil profile, higher pH, and lower polysaccharides. This was true for both 20 and 30 yr of treatment. Grazing effects on aggregate stability were observed only after 30 yr with spring grazing leading to a more stable structure with a mean weight diameter (MWD) of 1.5 mm and 32% and 10% of aggregates in the 2- to 6-mm and 1- to 2-mm size fractions, respectively, compared with a MWD of 1.0 mm and 20% and 6% under fall grazing. Greater soil bulk density, mechanical resistance, and pH were observed under the grazed treatment relative to the control without grazing, but as we used a moderate stocking rate the impacts were not as great as in previous studies, which used heavy stocking rates. Our findings show that long-term grazing at a moderate stocking rate of 0.6 AUM ha−1did not have critical detrimental effects on soil properties as some land managers and ranchers have suggested.

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Leão, Tairone Paiva, i Álvaro Pires da Silva. "A statistical basis for selecting parameters for the evaluation of soil penetration resistance". Scientia Agricola 63, nr 6 (grudzień 2006): 552–57. http://dx.doi.org/10.1590/s0103-90162006000600007.

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Measurements of soil penetration resistance (SR) have been frequently used for the evaluation of soil structural quality for plant growth. However, different data analysis approaches have been used, without a previous evaluation of their statistical quality. In this study we tested the hypothesis that the mean is the parameter with best statistical properties to evaluate alterations in soil penetration resistance in response to soil use and management, as compared to other SR statistical parameters. Undisturbed (5 × 5 cm) soil cores were collected from three sampling sites with different degrees of compaction: an undisturbed site under native scierophylous forest (NC); a site under short-duration grazing with post-grazing residue maintained at 2.0 to 2.5 Mg (Total Dry Matter) TDM ha-1 (LR); and a site under short-duration grazing with post-grazing residue maintained at 3.0 to 3.5 Mg TDM ha-1 (HR). The statistical quality of the parameters from undisturbed soil samples of SR profiles: mean (x), median (M), maximum (max), percentage of linear penetrability at 2 MPa (PLP2MPa), and the parameters from Probit analysis intercept (n) and slope (m) was evaluated using the ANOVA and LSD tests. Results from the F ratio, P > F values and LSD tests show that mean, median and maximum were the parameters with better statistical properties as criteria to evaluate alterations in soil penetration resistance in response to soil use and management as compared to other statistical SR parameters, validating the hypothesis of the research.

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Taddese, G., M. A. Mohamed Saleem i W. Ayalneh. "Effect of livestock grazing on physical properties of a cracking and self-mulching Vertisol". Australian Journal of Experimental Agriculture 42, nr 2 (2002): 129. http://dx.doi.org/10.1071/ea00155.

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The impact of grazing on physical properties of Vertisol was studied from 1996 to 2000 in the Ethiopian highlands. The study was conducted at 2 sites with 0–4 and 4–8% slopes at Tero Jemjem watershed in Ginchi, 80 km west of Addis Ababa. The objective of the study was to compare selected soil physical properties at different grazing pressures and slopes. The stocking rate was moderate grazing 1.8 animal-unit months per hectare (1.8 AUM/ha), heavy grazing 3.0 AUM/ha and a control treatment with no grazing. The result showed that heavy grazing pressure removed grass cover, which consequently enhanced soil cracking. Effect of livestock trampling on soil resistance to penetration (indicated by penetrometer readings) was higher in the heavily grazed plots than in non-grazed plots. Penetrometer readings were influenced by soil moisture content. Low moisture content was observed in the heavily grazed plots at both sites. The infiltration of accumulated water to the soil matrix was lower in heavily grazed plots.

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Neiva Júnior, Eudes, Wellington Willian Rocha, Bruno Silva Pires, Múcio Mágno de Melo Farnezi, Moacir de Souza Dias Junior, Danilo Fernandes Borges de Freitas, Enilson de Barros Silva i Gianniini Alexsandra de Oliveira Carvalho. "COMPRESSIBLITY AND PENETRABILITY OF LATOSSOLO VERMELHO-AMARELO DISTRÓFICO (OXISOL) UNDER VARIED MANAGEMENT SYSTEMS AND LAND USES". Revista Brasileira de Ciência do Solo 39, nr 1 (luty 2015): 86–93. http://dx.doi.org/10.1590/01000683rbcs20150032.

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Soil compaction is one of the main degradation causes, provoked by inappropriate agricultural practices that override the limitations of the soil physical properties. Preconsolidation pressure and penetration resistance have proved effective as alternative to assess and identify soil compaction. Based on the interpretation of these physico-mechanical parameters, compaction can be prevented with a better adjusted soil management. This study was performed to generate preconsolidation pressure and penetration resistance models for Latososlo Vermelho-Amarelo distrófico (Oxisol) under various managements and uses; and evaluate which of these would lead to degradation or degradation susceptibility. The study was carried out in Curvelo, MG. Two managements and one land use were evaluated: no-tillage, sheep grazing and natural forest. Undisturbed soil samples collected from the 0-5 cm layer were subjected to uniaxial compression and penetration resistance tests. Preconsolidation pressure models for forest and no-tillage soils were not statistically different, demonstrating a low degradation potential in no-tillage systems. Preconsolidation pressure was higher in soil under sheep grazing at all water retention tensions and penetration resistance values were higher than under native forest indicating animal trampling as a potential degradation factor. Neither management presented penetration resistance values above 2 MPa at field capacity moisture. Only under sheep grazing the soil penetrability was near 2 MPa at field capacity and values greater than 2 MPa at 0.2 kg kg-1.

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Adiba, Sandrine, Clément Nizak, Minus van Baalen, Erick Denamur i Frantz Depaulis. "From Grazing Resistance to Pathogenesis: The Coincidental Evolution of Virulence Factors". PLoS ONE 5, nr 8 (11.08.2010): e11882. http://dx.doi.org/10.1371/journal.pone.0011882.

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Erken, Martina, Markus Weitere, Staffan Kjelleberg i Diane McDougald. "In situ grazing resistance of Vibrio cholerae in the marine environment". FEMS Microbiology Ecology 76, nr 3 (1.03.2011): 504–12. http://dx.doi.org/10.1111/j.1574-6941.2011.01067.x.

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Sarnelle, Orlando. "Daphnia as keystone predators: effects on phytoplankton diversity and grazing resistance". Journal of Plankton Research 27, nr 12 (1.12.2005): 1229–38. http://dx.doi.org/10.1093/plankt/fbi086.

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Taylor, Richard B., Erik Sotka i Mark E. Hay. "Tissue-specific induction of herbivore resistance: seaweed response to amphipod grazing". Oecologia 132, nr 1 (czerwiec 2002): 68–76. http://dx.doi.org/10.1007/s00442-002-0944-2.

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NAKAMURA, Kanji, i Masao FUKUDA. "BACTERIAL GRAZING-RESISTANCE DEVELOPED DURING CO-EXISTENCE WITH A BACTERIVOROUS PROTIST". Journal of JSCE 9, nr 1 (2021): 86–93. http://dx.doi.org/10.2208/journalofjsce.9.1_86.

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Scheffer-Basso, Simone Meredith, i Andreissi Mileski Muniz. "Grazing resistance mechanisms in alfalfas of different aptitude in the juvenile stage". Revista Brasileira de Zootecnia 39, nr 8 (sierpień 2010): 1684–90. http://dx.doi.org/10.1590/s1516-35982010000800009.

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This study aimed at verifying whether juvenile plants of alfalfa cultivars with different aptitude (grazingtype: Alfagraze and ABT 805; hay-type: Crioula) show morphophysiological differences in order to develop a protocol for early selection for grazing persistence. Two experiments were conducted in a greenhouse, in completely randomized design and three repeplicates. In Experiment 1, plants were evaluated from successive destructive harvests at 60, 90, 120 and 150 days of age. In Experiment 2, plants at 150 days of age were cut to a 10-cm stubble and harvested at 15 and 30 days of regrowth. In Experiment 1, Alfagraze showed the lowest height (19 cm), internode length (1.4 cm) and apical bud accessibility (15.3 cm). Grazing-type cultivars did not differ significantly for subterranean hypocotyl diameter (3.5 mm) on the mean ages, and at 120 days of age they had lower number of leaves (56/plant) and axillary stem (2.5/plant) number as well as aerial dry matter accumulation (DM = 0.99 g/plant) in comparison to Crioula. At 150 days of age, Alfagraze had the lowest aerial dry matter accumulation (0.86 g/plant) compared to the other cultivars (1.8 g/plant). In Experiment 2, Alfagraze had higher leaf number (172/plant) compared to the mean of ABT 805 and Crioula (114/plant). The characters with the highest relative contribution for genetic divergence were number of leaves at 120 days of age (Experiment 1) and at 15 and 30 days of regrowth (Experiment 2) totalizing 71.5%. The highest average Euclidean distance (d = 12.3) was from Alfagraze to Crioula and the smallest from ABT 805 to Crioula (d = 8.92). At the juvenile stage, it is possible to identify some grazing avoidance mechanisms in alfafa, such as the small plant height, lower apical bud accessibility and short internodes, as well as one of the grazing tolerance mechanisms, which is the increase in the number of leaves after cutting. For these characters, early selection is possible and Alfagraze can be used as witness.

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Zheng, S. X., W. H. Li, Z. C. Lan, H. Y. Ren, K. B. Wang i Y. F. Bai. "Testing functional trait-based mechanisms underpinning plant responses to grazing and linkages to ecosystem functioning in grasslands". Biogeosciences Discussions 11, nr 9 (10.09.2014): 13157–86. http://dx.doi.org/10.5194/bgd-11-13157-2014.

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Abstract. Abundant evidence has shown that grazing alters plant functional traits, ecological strategies, community structure, and ecosystem functioning of grasslands. Few studies, however, have examined how plant responses to grazing are mediated by resource availability and functional group identity. We test functional trait-based mechanisms underlying the responses of different life forms to grazing and linkages to ecosystem functioning along a soil moisture gradient in the Inner Mongolia grassland. A principal component analysis (PCA) based on 9 traits × 276 species matrix showed that the plant size spectrum (i.e., individual biomass), leaf economics spectrum (leaf N content and leaf density), and light competition spectrum (height and stem-leaf biomass ratio) distinguished plant species responses to grazing. The three life forms exhibited differential strategies as indicated by trait responses to grazing. The annuals and biennials adopted grazing-tolerant strategies associated with high growth rate, reflected by high leaf N content and specific leaf area. The perennial grasses exhibited grazing-tolerant strategies associated with great regrowth capacity and high palatability scores, whereas perennial forbs showed grazing-avoidant strategies with short stature and low palatability scores. In addition, the dominant perennial bunchgrasses exhibited mixed tolerance–resistance strategies to grazing and mixed acquisitive–conservative strategies in resource utilization. Grazing increased the relative abundance of perennial forbs with low palatability in the wet and fertile meadow, but it promoted perennial grasses with high palatability in the dry and infertile typical steppe. Our findings suggest that the effects of grazing on plant functional traits are dependent on both the abiotic (e.g., soil moisture) and biotic (e.g., plant functional group identity and composition) factors. Grazing-induced shifts in functional group composition are largely dependent on resource availability, particularly water availability.

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Franzluebbers, Alan J., John A. Stuedemann i Dorcas H. Franklin. "Water infiltration and surface-soil structural properties as influenced by animal traffic in the Southern Piedmont USA". Renewable Agriculture and Food Systems 27, nr 4 (26.08.2011): 256–65. http://dx.doi.org/10.1017/s1742170511000378.

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AbstractSurface-soil structural condition in perennial pastures is expected to be modified by how forage is (a) harvested through haying or grazing and (b) stimulated through source of nutrients applied, as well as by compactive forces, e.g., grazing cattle or hay harvest machinery. Changes in surface-soil condition can affect hydrologic processes that have important implications for plant growth, greenhouse gas emissions and off-site water quality. We determined the effects of harvest management and nutrient source on the rate of ponded water infiltration and penetration resistance in a bermudagrass [Cynodon dactylon (L.) Pers.]/tall fescue (Lolium arundinaceum Schreb. S.J. Darbyshire) pasture on a Typic Kanhapludult in Georgia. During a period when soil was wet (61% water-filled pore space), the rate of water infiltration was 2.8 ± 1.5 times greater when forage was left unharvested as when hayed or grazed (mean ± standard deviation among nine nutrient source × harvest management comparisons). During a subsequent period, when soil was dry (28% water-filled pore space), the rate of water infiltration followed the same treatment pattern, but was not statistically different among harvest-management practices (1.5 ± 0.4 times greater between unharvested and other systems). Penetration resistance of the surface at 10 cm depth followed the order: unharvested (62 J) < hayed (100 J) < low grazing pressure (119 J) < high grazing pressure (137 J). Water infiltration during the wet period was negatively related (P ⩽ 0.01) to soil-water content (r = − 0.57), penetration resistance at 0–10 cm depth (r = − 0.50) and bulk density at 3–6 cm depth (r = − 0.53), but was positively related to surface residue C (r = 0.47) and soil organic C concentration at 12–20 cm depth (r = 0.42). These results suggest that complex soil physical (i.e., aggregation, penetration resistance and infiltration) and biological (i.e., plant growth, surface residues and soil organic matter) interactions occur in pastures. We conclude that well-managed grazing systems with excellent ground cover should have adequate hydrologic condition to promote pasture productivity and limit environmental contamination from runoff. Further work is needed to understand the linkages between field- and watershed-scale hydrology in perennial pastures and their implications on water quality.

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Katepa-Mupondwa, F., A. Singh, S. R. Smith Jr. i W. P. McCaughey. "Grazing tolerance of alfalfa (Medicago spp.) under continuous and rotational stocking systems in pure stands and in mixture with meadow bromegrass (Bromus riparius Rehm. syn. B. biebersteinii Roem & Schult)". Canadian Journal of Plant Science 82, nr 2 (1.04.2002): 337–47. http://dx.doi.org/10.4141/p00-017.

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The continuing development of adapted alfalfa (Medicago sativa L.) cultivars that combine high yield, disease resistance, winterhardiness, and grazing tolerance is of great value to the beef cattle industry in western Canada. This study evaluated alternative management strategies and plant measurements for assessing the grazing tolerance of alfalfa cultivars over 3 yr. Seven hay-type, four pasture-type, and one dual-purpose (hay or graze) cultivars were established in pure stands and in mixture with meadow bromegrass (Bromus riparius Rehm. syn.B. biebersteinii Roem & Schult). Stands were defoliated under continuous or rotational stocking with beef cattle (Bos taurus). Plants we reassessed for winterhardiness, percent alfalfa within row, percent alfalfa cover, basal area and species composition. Continuous stocking resulted in consistent and significant differences between cultivars, whether persistence was measured as percent alfalfa within row, percent cover and basal area, in both pure and mixed stands (P < 0.05). High correlations between measurement techniques (r = 0.74 to 0.99; P < 0.05) confirmed the value of alfalfa within row and alfalfa cover as time and labour efficient methods to evaluate grazing persistence. Competition between alfalfa and meadow bromegrass resulted in a significant confounding effect under rotational stocking (P < 0.05). Winter injury was identified as an important criteria to evaluate for grazing persistence. The most grazing-tolerant genotypes were selected for subsequent breeding efforts to combine winterhardiness, grazing tolerance, and high productivity. This research showed that grazing method, grass competition, and severe winter conditions strongly influence differential survival of alfalfa cultivars under grazing in western Canada. Key words: Alfalfa, grazing tolerance, grazing systems, Medicago sativa L., Medicago falcata L. Arcang, persistence

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Beukes, D. E., K. L. Glennon i S. Archibald. "Consequences of grazing resistance adaptations for Rhodohypoxis baurii var. platypetala population genetics". South African Journal of Botany 115 (marzec 2018): 316–17. http://dx.doi.org/10.1016/j.sajb.2018.02.148.

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Sun, Shuyang, Qi Xiang Martin Tay, Staffan Kjelleberg, Scott A. Rice i Diane McDougald. "Quorum sensing-regulated chitin metabolism provides grazing resistance to Vibrio cholerae biofilms". ISME Journal 9, nr 8 (23.01.2015): 1812–20. http://dx.doi.org/10.1038/ismej.2014.265.

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Ahmed, Haseeb, Douglas R. Call, Robert J. Quinlan i Jonathan K. Yoder. "Relationships between livestock grazing practices, disease risk, and antimicrobial use among East African Agropastoralists". Environment and Development Economics 23, nr 1 (23.10.2017): 80–97. http://dx.doi.org/10.1017/s1355770x17000341.

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AbstractLivestock health is economically important for agropastoral households whose wealth is held partly as livestock. Households can invest in disease prevention and treatment, but livestock disease risk is also affected by grazing practices that result in inter-herd contact and disease transmission in regions with endemic communicable diseases. This paper examines the relationships between communal grazing and antimicrobial use in Maasai, Chagga and Arusha households in northern Tanzania. We develop a theoretical model of the economic connection between communal grazing, disease transmission risk, risk perceptions, and antimicrobial use, and derive testable hypotheses about these connections. Regression results suggest that history of disease and communal grazing are associated with higher subjective disease risk and greater antimicrobial use. We discuss the implications of these results in light of the potential for relatively high inter-herd disease transmission rates among communal grazers and potential contributions to antimicrobial resistance due to antimicrobial use.

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Puk, LD, N. Cernohorsky, A. Marshell, J. Dwyer, K. Wolfe i PJ Mumby. "Species-specific effects of herbivorous fishes on the establishment of the macroalga Lobophora on coral reefs". Marine Ecology Progress Series 637 (5.03.2020): 1–14. http://dx.doi.org/10.3354/meps13262.

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Herbivory is a key ecosystem function that influences ecosystem trajectories. However, interactions between plants and herbivores are species-specific and change throughout the plants’ lifetime. On coral reefs, herbivorous fishes reduce competition between corals and macroalgae through their grazing activity, thereby regulating the ecosystem state. Grazing vulnerability of marine algae generally decreases with increasing algal size. Therefore, the removal of newly settled recruits by herbivorous fish is likely important in preventing macroalgal blooms and reducing competition with corals. We studied the grazing susceptibility of recruits of the brown macroalga Lobophora to multiple fish species through a combination of feeding observations and manipulative in situ and ex situ experiments. Further, we recorded short-term Lobophora growth patterns and adult survival over 9 wk. Lobophora recruits were more susceptible to herbivory than adults, likely owing to their smaller size. However, recruit mortality was driven by only 3 of the studied species: Acanthurus nigrofuscus, Scarus niger and Chlorurus spilurus, whereas other common herbivores did not remove any Lobophora recruits. Our data also suggest variable growth and recruitment among months. These findings point to a possible increase in grazing resistance with age for Lobophora. As such, a decrease in grazing pressure by key fish species controlling Lobophora recruits could permit Lobophora to establish more grazing-tolerant adult populations.

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Ma, Wenjing, Jin Li, Saheed Olaide Jimoh, Yujuan Zhang, Fenghui Guo, Yong Ding, Xiliang Li i Xiangyang Hou. "Stoichiometric ratios support plant adaption to grazing moderated by soil nutrients and root enzymes". PeerJ 7 (10.06.2019): e7047. http://dx.doi.org/10.7717/peerj.7047.

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Background Vegetation succession is one of the major driving processes of grassland degradation. Stoichiometry significantly contributes to vegetation dynamics. However, a knowledge gap exists in how soil nutrients and root enzymes influence the stoichiometric ratio to affect vegetation dynamics. Methods To address these questions, we selected a dominant species (Leymus chinensis (Trin.) Tzvel.) and a degraded-dominant species (Artemisia frigida Willd.) under different management regimes (enclosure and grazing) on the Inner Mongolia steppe. We measured (i) plant nutrient concentrations, (ii) root enzymes and (iii) soil nutrients to investigate how the selected plant species responded to grazing. Results The results show that: (i) N and P concentrations and the C:N:P ratio in different organs are significantly affected by grazing, and there is variation in the plant species’ response. Grazing significantly increased N and P in the leaves and stems of L. chinensis and the stems and roots of A. frigida. (ii) Grazing significantly increased the activities of glutamine synthase but decreased the activities of acid phosphatase in L. chinensis. The nitrate reductase and acid phosphatase activities significantly increased in A. frigida under grazing conditions. (iii) Grazing decreased the total nitrogen, total phosphorus, and available nitrogen, but increased the available phosphorus in the soil. Conclusion We conclude that A. frigida is better adapted to grazing than L. chinensis, possibly because of its relatively increased stem and root growth, which enhance population expansion following grazing. Conversely, L. chinensis showed increased leaf and stem growth, but suffered nutrient and biomass loss as a result of excessive foraging by livestock, which severely affected its ability to colonize. Root enzymes coupled with soil nutrients can regulate plant nutrients and stoichiometric ratios as an adaptive response to grazing. Thus, we demonstrated that stoichiometric ratios allow species to better withstand grazing disturbances. This study provides a new understanding of the mechanisms involved in grazing-resistance within a plant-soil system.

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Li, Si, i Stefanie M. H. Ismar. "Transcriptome, Biochemical and Growth Responses of the Marine Phytoplankter Phaeodactylum Tricornutum Bohlin (Bacillariophyta) to Copepod Grazer Presence". Cellular Physiology and Biochemistry 46, nr 3 (2018): 1091–111. http://dx.doi.org/10.1159/000488839.

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Background/Aims: As a model organism for a pleiomorphic marine planktonic primary producer, Phaeodactylum tricornutum has been studied on a molecular level under diverse cultural conditions. But little is known about its morphological, nutritional or transcriptomic responses under grazing stress. Methods: To assess microalgal molecular and cellular responses to grazer presence, we conducted transcriptome profiling in combination with growth rate, biovolume, fatty acid content, carbon and nitrogen content measurements in the model diatom Phaeodactylum tricornutum. RNA-sequencing was used to evaluate the transcriptomic response to grazing stress for P. tricornutum strain CCAP 1055/1. Results: Among the differentially expressed genes, we found down-regulation of genes involved in pathogen resistance, and in fatty acid biosynthesis pathways, while mitosis-involved genes were up-regulated. Experimentally testing morphological and biochemical responses in five strains of the species, we detected strain-specific significant effects of simulated grazing pressure in altered growth rates, biovolume and nutritional composition. Conclusion: Our research reveals the associated molecular and cellular responses to grazing effects in P. tricornutum and extends the understanding of co-evolutionary roles in regulating grazing defence between P. tricornutum and its grazer.

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Döll, Katharina, Subhankar Chatterjee, Stefan Scheu, Petr Karlovsky i Marko Rohlfs. "Fungal metabolic plasticity and sexual development mediate induced resistance to arthropod fungivory". Proceedings of the Royal Society B: Biological Sciences 280, nr 1771 (22.11.2013): 20131219. http://dx.doi.org/10.1098/rspb.2013.1219.

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Prey organisms do not tolerate predator attack passively but react with a multitude of inducible defensive strategies. Although inducible defence strategies are well known in plants attacked by herbivorous insects, induced resistance of fungi against fungivorous animals is largely unknown. Resistance to fungivory is thought to be mediated by chemical properties of fungal tissue, i.e. by production of toxic secondary metabolites. However, whether fungi change their secondary metabolite composition to increase resistance against arthropod fungivory is unknown. We demonstrate that grazing by a soil arthropod, Folsomia candida , on the filamentous fungus Aspergillus nidulans induces a phenotype that repels future fungivores and retards fungivore growth. Arthropod-exposed colonies produced significantly higher amounts of toxic secondary metabolites and invested more in sexual reproduction relative to unchallenged fungi. Compared with vegetative tissue and asexual conidiospores, sexual fruiting bodies turned out to be highly resistant against fungivory in facultative sexual A. nidulans . This indicates that fungivore grazing triggers co-regulated allocation of resources to sexual reproduction and chemical defence in A. nidulans . Plastic investment in facultative sex and chemical defence may have evolved as a fungal strategy to escape from predation.

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Omokanye, Akim, Calvin Yoder, Lekshmi Sreekumar, Liisa Vihvelin i Monika Benoit. "On-farm Assessments of Pasture Rejuvenation Methods on Soil Quality Indicators in Northern Alberta (Canada)". Sustainable Agriculture Research 7, nr 2 (18.04.2018): 74. http://dx.doi.org/10.5539/sar.v7n2p74.

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The study was aimed at providing livestock producers with options on practical methods to improve soil quality of pastures for improved forage production and livestock carrying capacity. The study was carried out on-farm from 2015 to 2017 at two sites in northern Alberta, Canada. The methods of rejuvenation (treatments) evaluated were: sub-soiling, break & re-seed (pasture renewal), a combination of manure application plus subsoiling, pasture rest, inorganic fertilizer application, high stock density grazing and bale grazing. A check/control treatment was included for comparison. For break & re-seed, the forage mixture seeded (16.8 kg ha-1) consisted of 60% grasses and 40% legumes. Overall, bale grazing improved soil organic matter (SOM) by up to 3.80% over other methods including check. In terms of soil compaction penetration resistance, water infiltration rate, water content and nutrients particularly N, P and K, bale grazing system as a method of rejuvenating old pastures significantly showed higher values than check at both sites. Without having to break and re-seed old pastures, the first option that livestock producers would have success with in improving soil quality for better pasture productivity would be bale grazing. The next two methods or rejuvenation strategies with great potential for improving soil conditions for pastures would be a combination of manure application plus subsoil in fall and high stock density grazing.

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Veiga, Milton Da, Carla Maria Pandolfo, Alvadi Antonio Balbinot Junior i Leandro Durigon. "Effects on Soil and Crop Properties of Forms of Sowing, Deferral Intervals and Fertilisation of the Annual Winter Forage in a Crop-Livestock Integration System". Journal of Agricultural Science 8, nr 5 (13.04.2016): 15. http://dx.doi.org/10.5539/jas.v8n5p15.

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The use of cropland to grow annual winter forages that are managed using direct grazing can affect the quality of the soil and the yield of summer crops grown in succession. This study aimed to evaluate the effect that the form of sowing (direct sowing and sowing + harrowing), the deferral intervals (ungrazed and grazing stopped at 14 days and 28 days before and on the day of forage desiccation) and the fertilisation of the annual winter forage (with and without application of 8 m3 ha-1 of poultry litter) had on the chemical properties of soil, resistance to penetration, residual forage biomass, soil cover and yield of corn and soybean from the third to the sixth year of experimentation. The forms of sowing did not affect the chemical properties of the soil, resistance to penetration, the residual forage biomass and the yield of the soybean and corn grown in rotation. The grazing of annual winter forage did not affect the chemical properties of soil and the yield of soybean and corn grown in succession, but residual forage biomass was reduced and resistance to penetration was increased with decreasing deferral intervals. In turn, the fertilisation of winter forages improved the quality of the chemical properties of the soil and increased the residual forage biomass and crop yields in most of the four years examined in this experiment.

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Yan, Dongqing, Jing Ren, Jiamei Liu, Yu Ding i Jianming Niu. "De novo assembly, annotation, marker discovery, and genetic diversity of the Stipa breviflora Griseb. (Poaceae) response to grazing". PLOS ONE 15, nr 12 (22.12.2020): e0244222. http://dx.doi.org/10.1371/journal.pone.0244222.

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Grassland is one of the most widely-distributed ecosystems on Earth and provides a variety of ecosystem services. Grasslands, however, currently suffer from severe degradation induced by human activities, overgrazing pressure and climate change. In the present study, we explored the transcriptome response of Stipa breviflora, a dominant species in the desert steppe, to grazing through transcriptome sequencing, the development of simple sequence repeat (SSR) markers, and analysis of genetic diversity. De novo assembly produced 111,018 unigenes, of which 88,164 (79.41%) unigenes were annotated. A total of 686 unigenes showed significantly different expression under grazing, including 304 and 382 that were upregulated and downregulated, respectively. These differentially expressed genes (DEGs) were significantly enriched in the “alpha-linolenic acid metabolism” and “plant-pathogen interaction” pathways. Based on transcriptome sequencing data, we developed eight SSR molecular markers and investigated the genetic diversity of S. breviflora in grazed and ungrazed sites. We found that a relatively high level of S. breviflora genetic diversity occurred under grazing. The findings of genes that improve resistance to grazing are helpful for the restoration, conservation, and management of desert steppe.

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Leathwick, D. M., i R. B. Besier. "The management of anthelmintic resistance in grazing ruminants in Australasia—Strategies and experiences". Veterinary Parasitology 204, nr 1-2 (lipiec 2014): 44–54. http://dx.doi.org/10.1016/j.vetpar.2013.12.022.

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Lebret, Karen, María Fernández Fernández, Camilla H. C. Hagman, Karin Rengefors i Lars-Anders Hansson. "Grazing resistance allows bloom formation and may explain invasion success of Gonyostomum semen". Limnology and Oceanography 57, nr 3 (16.04.2012): 727–34. http://dx.doi.org/10.4319/lo.2012.57.3.0727.

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Muñiz-Lagunes, Abel, Roberto González-Garduño, Maria Eugenia López-Arellano, Rodolfo Ramírez-Valverde, Agustín Ruíz-Flores, Guadalupe García-Muñiz, Gabriel Ramírez-Vargas, Pedro Mendoza-de Gives i Glafiro Torres-Hernández. "Anthelmintic resistance in gastrointestinal nematodes from grazing beef cattle in Campeche State, Mexico". Tropical Animal Health and Production 47, nr 6 (15.04.2015): 1049–54. http://dx.doi.org/10.1007/s11250-015-0826-3.

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Thomas, Patrick K., Gary P. Dunn, Erik R. Coats, Deborah T. Newby i Kevin P. Feris. "Algal diversity and traits predict biomass yield and grazing resistance in wastewater cultivation". Journal of Applied Phycology 31, nr 4 (20.02.2019): 2323–34. http://dx.doi.org/10.1007/s10811-019-01764-2.

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Burke, Joan M., i James E. Miller. "Multi-species Grazing for Control of Gastrointestinal Nematodes – a Review". Journal of Animal Science 99, Supplement_2 (1.05.2021): 36–37. http://dx.doi.org/10.1093/jas/skab096.066.

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Abstract Multi-species grazing, alternate grazing of cattle with sheep or goats, offers benefits to gastrointestinal nematode (GIN) control as GIN species differ between hosts. In the Southeastern United States, common GIN species of cattle include Cooperia spp., Ostertagia ostertagi, Haemonchus spp., whereas species of sheep and goats are Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp., Cooperia curticei, and Oesophagostomum spp. Anthelmintic resistance is widely prevalent in small ruminants, and is an increasing problem in cattle, but remains less prevalent. Thus, it is recommended to farmers to use a multi-faceted approach of GIN control, including multi-species grazing. Because management differs between cattle and small ruminants in regard to copper tolerance in minerals, predator control and fencing, alternate grazing of species has most commonly been used. Other considerations include age or susceptibility to GIN, as young calves may be vulnerable to GIN, but mature cows often have negligible GIN infection. Similarly, weanling lambs and kids are susceptible, and depending on breed, adults range from highly resistant to susceptible. Research indicates that GIN burden of more resistant animals is less influenced by multi-species grazing, and highly susceptible animals will likely need additional measures of control. The more resistant species used in the multi-species grazing may lend more control to the more susceptible. Some research showed reductions in O. ostertagi, but not C. oncophora in cattle during extended grazing of cattle and sheep, and reductions of H. contortus and T. colubriformis in sheep. However, other research reported similar worm burdens. Weight gains were improved in lambs grazed alternately with cattle in some studies, and most studies showed little benefit to cattle. Little has been published on alternate grazing with cattle and goats. The complex interactions, larger plot sizes needed, and time required to complete experiments limits published studies of this important management scheme.

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Halde, C., A. M. Hammermeister, N. L. Mclean, K. T. Webb i R. C. Martin. "Soil compaction under varying rest periods and levels of mechanical disturbance in a rotational grazing system". Canadian Journal of Soil Science 91, nr 6 (listopad 2011): 957–64. http://dx.doi.org/10.4141/cjss2011-026.

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Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compaction under varying rest periods and levels of mechanical disturbance in a rotational grazing system. Can. J. Soil Sci. 91: 957–964. In Atlantic Canada, data are limited regarding the effect of grazing systems on soil compaction. The objective of the study was to determine the effect of intensive and extensive rotational pasture management treatments on soil bulk density, soil penetration resistance, forage productivity and litter accumulation. The study was conducted on a fine sandy loam pasture in Truro, Nova Scotia. Each of the eight paddocks was divided into three rotational pasture management treatments: intensive, semi-intensive and extensive. Mowing and clipping were more frequent in the intensive than in the semi-intensive treatment. In the extensive treatment, by virtue of grazing in alternate rotations, the rest period was doubled than that of the intensive and semi-intensive treatments. Both soil bulk density (0–5 cm) and penetration resistance (0–25.5 cm) were significantly higher in the intensive treatment than in the extensive treatment, for all seasons. Over winter, bulk density decreased significantly by 6.8 and 3.8% at 0–5 and 5–10 cm, respectively. A decrease ranging between 40.5 and 4.0% was observed for soil penetration resistance over winter, at 0–1.5 cm and 24.0–25.5 cm, respectively. The intensive and semi-intensive treatments produced significantly more available forage for grazers annually than the extensive treatment. Forage yields in late May to early June were negatively correlated with spring bulk density.

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Łabanowski, Jerzy, i A. Ossowska. "Properties of Duplex Stainless Steel Surface Layers after Burnishing Process". Solid State Phenomena 165 (czerwiec 2010): 118–23. http://dx.doi.org/10.4028/www.scientific.net/ssp.165.118.

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This paper investigates stress corrosion cracking resistance of cold worked layers of 25 Cr duplex stainless steel grade UR52N+. The surface layers were processed through burnishing treatment. The residual stresses at surface layers were determined using grazing angle incidence X-ray diffraction method (g-sin2 Ψ). Corrosion tests were performed with the use of Slow Strain Rate Test technique in boiling 35% MgCl2 solution. It has been demonstrated that burnishing treatment increases corrosion resistance of the steel. Stress corrosion cracking resistance depends on the magnitude of cold work at surface layers. High level of cold work diminishes corrosion resistance.

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Apple, Jude K., Suzanne L. Strom, Brian Palenik i Bianca Brahamsha. "Variability in Protist Grazing and Growth on Different Marine Synechococcus Isolates". Applied and Environmental Microbiology 77, nr 9 (11.03.2011): 3074–84. http://dx.doi.org/10.1128/aem.02241-10.

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ABSTRACTGrazing mortality of the marine phytoplanktonSynechococcusis dominated by planktonic protists, yet rates of consumption and factors regulating grazer-Synechococcusinteractions are poorly understood. One aspect of predator-prey interactions for which little is known are the mechanisms by whichSynechococcusavoids or resists predation and, in turn, how this relates to the ability ofSynechococcusto support growth of protist grazer populations. Grazing experiments conducted with the raptorial dinoflagellateOxyrrhis marinaand phylogenetically diverseSynechococcusisolates (strains WH8102, CC9605, CC9311, and CC9902) revealed marked differences in grazing rates—specifically that WH8102 was grazed at significantly lower rates than all other isolates. Additional experiments using the heterotrophic nanoflagellateGoniomonas pacificaand the filter-feeding tintinnid ciliateEutintinnissp. revealed that this pattern in grazing susceptibility among the isolates transcended feeding guilds and grazer taxon.Synechococcuscell size, elemental ratios, and motility were not able to explain differences in grazing rates, indicating that other features play a primary role in grazing resistance. Growth of heterotrophic protists was poorly coupled to prey ingestion and was influenced by the strain ofSynechococcusbeing consumed. AlthoughSynechococcuswas generally a poor-quality food source, it tended to support higher growth and survival ofG. pacificaandO. marinarelative toEutintinnissp., indicating that suitability ofSynechococcusvaries among grazer taxa and may be a more suitable food source for the smaller protist grazers. This work has developed tractable model systems for further studies of grazer-Synechococcusinteractions in marine microbial food webs.

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Niezen, J. H., T. S. Waghorn, W. A. G. Charleston i G. C. Waghorn. "Growth and gastrointestinal nematode parasitism in lambs grazing either lucerne (Medicago sativa) or sulla (Hedysarum coronarium) which contains condensed tannins". Journal of Agricultural Science 125, nr 2 (październik 1995): 281–89. http://dx.doi.org/10.1017/s0021859600084422.

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SUMMARYTwo grazing experiments were undertaken to evaluate the effects of sulla (Hedysarum coronarium) which contains condensed tannins (CT) and lucerne (Medicago sativa), which does not contain CT, on the performance of parasitized and non-parasitized lambs. The work was carried out near Palmerston North, New Zealand in 1992 and 1993.Experiment 1 used lambs which were either genetically ‘conventional’ or ‘resistant’ to gastrointestinal nematodes and which had a naturally acquired heavy parasite burden (faecal egg count (FEC) 1300–2500 eggs per gram faeces (epg)). They were either drenched to remove all the parasites or remained undrenched when allocated to pure swards of either sulla or lucerne for the 28-day experimental period. Liveweight gains of drenched lambs were higher with sulla (mean 302 g/day) than with lucerne (mean 245 g/day; P < 0·02) and rates of gain were not reduced (P = 0·10) by genetic resistance to nematodes. Undrenched lambs had mean faecal egg counts of 1090–2220 epg after 28 days, with higher counts in lambs grazing lucerne than in those grazing sulla (P < 0·05). Lambs grazing lucerne also had a much lower average daily gain (ADG) (mean 50 g/day) than those grazing sulla (mean 206 g/day; P < 0·0001). Resistant lambs had reduced (P = 0·07) ADG in the sulla treatment only.In Expt 2, lambs with a relatively low worm burden (average FEC 250 epg) were either drenched to remove all worms or dosed with 20 000 Trichostrongylus colubriformis infective larvae and grazed on pure sulla or lucerne swards for 42 days. Drenched lambs had a similar liveweight gain (mean 190 g/day) and wool growth when grazing either sulla or lucerne. Undrenched lambs grazing sulla had a greater ADG (mean 129 g/day) than those grazing lucerne (mean −39 g/day; P < 0·0001) and a higher rate of wool growth from mid-side patches (P < 0·009) and larger wool fibre diameter (P < 0·05) than those grazing lucerne. Undrenched lambs grazing sulla had lower FECs (P < 0·05) on days 14, 21, 35 and 42 than those grazing lucerne and lower (P < 0·05) Trichostrongylus colubriformis worm burdens at slaughter. Undrenched lambs had less perineal faecal contamination when grazing sulla rather than lucerne. Parasite-induced anorexia was evident in the lambs grazing lucerne but not in those grazing sulla.These findings demonstrate that the performance of lambs infected with nematode parasites can vary substantially when given feeds of a similar chemical composition. The superior performance of lambs grazing sulla was probably caused by condensed tannins, which decrease protein degradation in the rumen and can increase post-ruminal protein availability.

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