Browsing by Subject "grazing"
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Item Butterfly Responses To Management Of Disturbance-Dependent Ecosystems In North America And Australia.(2021-09) Leone, JuliaFire and grazing are primary sources of natural disturbance in grasslands and savannas worldwide, but they are also shaped by human impacts and decision-making. Appropriate management is therefore an essential goal for biodiversity conservation in disturbance-dependent landscapes. The butterflies which inhabit these ecosystems are reliant on the disturbances necessary for grassland and savanna persistence. Regular fire, herbivory, and drought shape and maintain these ecosystems, keeping woody plants from dominating. How, then, do butterflies persist and respond to disturbance in their chosen habitats? What management regimes are required in human-altered landscapes to conserve grassland and savanna butterfly biodiversity? I examine butterfly responses to management of disturbance-dependent ecosystems in North American and Australian using both taxonomic and functional trait lenses. In Chapter 1, I assess the impacts of current fire and grazing management regimes on butterfly communities in Minnesota tallgrass prairie and compare butterfly and bee responses to management. In Chapter 2, I assess the impacts of these same fire and grazing regimes on monarch butterflies (Danaus plexippus) and their milkweed host plants in Minnesota tallgrass prairie. In Chapter 3, I examine butterfly and butterfly resource responses to fire regimes in Australian tropical savanna, and in Chapter 4, I demonstrate the utility of trait-based ecology to explain global and mechanistic patterns in butterfly responses to fire by presenting and comparing butterfly traits associated with fire regimes in U. S. temperate prairie and Australian tropical savanna. I present findings that butterfly and bee abundances in tallgrass prairie are significantly negatively correlated. Butterfly abundance, but not species richness, is nearly twice as high at tallgrass prairie sites managed with fire compared to grazing, and prairie-associated grass-feeding butterflies are more abundant at sites with higher plant species richness. I find that monarch butterflies are also more abundant at tallgrass prairie sites managed with fire than with grazing, and that this association is not related to milkweed or forb frequencies, which are similar between burned and grazed prairies. In Australian tropical savanna, I find that recent, early dry season burning promotes butterfly diversity and abundance by increasing the supply of nectar resources in tropical savanna fire treatments. In my evaluation of butterfly traits associated with fire, diapause strategy, host plant specificity, wingspan, voltinism, and flight period are all associated with at least one fire treatment, but trait associations are not shared across Australian tropical savanna and U.S. temperate prairie. In tallgrass prairie, land managers and conservation practitioners interested in promoting butterfly abundance and diversity may consider increasing plant species richness and maintaining fire in the landscape. Because species composition differs between sites managed with fire and grazing and among sites managed for different numbers of years, I suggest a variety of management strategies is required to support the entire suite of butterfly species. In tropical savanna, land managers and conservation practitioners can ensure some areas of recent, early-season fire are maintained and focus on additional actions that will promote floral resource abundance and diversity, which will benefit butterflies as well as many other animal taxa. Trait-based ecology methods can help us understand the role of traits such as diapause strategy, host plant specificity, wingspan, voltinism, and flight period in explaining general patterns in butterfly responses to fire. However, to inform good conservation and management, trait-based findings should be tied back to the local species and landscapes being managed. The second chapter of this dissertation is published in Frontiers in Ecology and Evolution (Leone et al. 2019) and the first chapter is currently under review with the Journal of Insect Conservation. As a reflection of the collaborative nature of the work I present, I will use the first-person plural voice “we” throughout the rest of this dissertation.Item Forage quality and blood metabolites of horses grazing alfalfa, cool-season perennial grass, and teff(2018-07) DeBoer, MichelleThe impact of forage species on blood metabolites concentrations of grazing horses (Equus caballus L.) is unknown. However, these differences can be crucial as plasma amino acid (AA) concentrations as well as the glucose and insulin response of grazing horses can be indicators of nutritional status or metabolic health. As a result, the objectives of these studies were to determine the impact of different forage species on plasma AA concentrations, protein synthesis, as well as the glucose and insulin response across seasons. Research was conducted in May (spring), July (summer), September (fall), and late October (late-fall) in St. Paul, MN in 2016. However, the data collected was divided into three different studies (1) July samples taken during the first 4 hours were used to evaluate the forage and plasma AA concentrations (2) samples collected in July and September were included in the glucose and insulin response analysis of the regular grazing season and (3) May and October samples were used to analyze the glucose and insulin response during the extended grazing season. Forage treatments included alfalfa (Medicago sativa L.), a mixed perennial cool-season grass (CSG) and teff (Eragrostis tef [Zucc.] Trotter), however, not all forage species were grazed every season. Alfalfa and CSG were grazed in May while CSG and teff were grazed during the October, with all three species grazed in July and September. During these times, forages were grazed by six horses (24 ± 2 yr) randomly assigned to a forage in either a Latin-square or cross-over design. Jugular catheters were inserted 1 h prior to the start of grazing and horses had access to pasture starting at 08:00 h for either 4 or 8 h depending on the season. Jugular venous blood samples were collected from each horse prior to being turned out (0 h) and then at 2 hour intervals following turnout. Plasma and serum samples were collected and analyzed for AA, glucose, and insulin. Corresponding forage samples were taken by hand harvest. Equine muscle satellite cell cultures were treated with sera from grazing horses to assess de novo protein synthesis. Seasons were analyzed separately and data were analyzed using the MIXED procedure in SAS with P ≤ 0.05. When evaluating forage, AA were generally lowest in teff and highest in CSG (P ≤ 0.05). Significant differences in threonine concentration in the plasma were observed; there was no effect on de novo protein synthesis of cultured equine myotubes treated with plasma obtained from the grazing horses (P ≥ 0.20). As a result, although there were significant differences in forage AA content only plasma threonine concentration was different at 4 h with no effect on protein synthesis of cultured equine satellite cells. When evaluating the glucose and insulin response during the regular grazing season, teff generally had lower (P ≤ 0.05) equine digestible energy (DE), crude protein (CP) and nonstructural carbohydrates (NSC) compared to the other forages. Differences in peak insulin were observed between horses grazing CSG and teff during the fall grazing (P ≤ 0.05). Additionally, when evaluating the extended grazing season, teff had lower NSC than CSG in the late-fall (P ≤ 0.05) with subsequently lower average glucose, average insulin, and peak insulin in horses grazing teff compared to CSG (P ≤ 0.05).These results suggest grazing teff could lower the glucose and insulin response of some horses, specifically in the fall and late-fall, and may provide an alternative forage for horses with metabolic concerns,Item Forage quality of two cover crop grazing systems and meat quality of organic beef from crossbred dairy steers finished on forages(2017-09) Phillips, HannahThis study analyzed the yield, forage quality, and mineral composition of organic winter rye and winter wheat in grazing systems, and analyzed the meat quality, fatty acids, and consumer acceptability of beef from Holstein and crossbred organic dairy steers finished on winter rye and winter wheat pastures. Steers (n = 30) were assigned to one of three replicate breed groups at birth: (1) Holstein (n = 10), (2) crossbreeds comprised of Montbéliarde, Viking Red, and Holstein (n = 10), and (3) crossbreeds comprised of Normande, Jersey, and Viking Red (n = 10). Breed groups were randomly assigned to graze either winter rye or winter wheat during their finishing phase. The results suggest that winter rye and winter wheat cover crops are viable options for grazing cattle, and suggest beef from crossbred dairy steers leads to an improved fatty acid profile and greater consumer acceptability compared to Holstein steers.Item Grazing Systems Planning Guide(University of Minnesota Extension Service, 2003) Blanchet, Kevin; Moechnig, Howard; DeJong-Hughes, JodiItem Match Made In Heaven Farmers Survey(2024-09-12) University of Minnesota; DiGiacomo, Gigi; gigid@umn.edu; DiGiacomo, Gigi; University of Minnesota Dept. of Applied EconomicsThis survey is part of the Match Made in Heaven (MMIH) project that seeks to foster re-integration of livestock and grain production systems in the North Central, U.S. Region by generating information on producer production practices, attitudes, and goals. One of the project deliverables were qualitative results from this producer survey which will be used to help guide the development of educational programming and other activities aimed at promoting environmental, economic, and social benefits of integrated livestock and crop systems in the North Central, U.S. Region.