This thesis investigated the role of carbohydrates in the dietary choices of ruminants with an emphasis on dairy cows. The first two experiments investigated the ability of sheep to select between feeds based on their carbohydrate degradability. A further two indoor experiments using dairy cows were designed to establish whether post-ingestive feedback from rumen fluid propionic acid concentration influenced preference. The final experiment examined the potential of ryegrass bred for high water soluble carbohydrate (WSC) concentrations to increase the long-term (9 days) preferences and intake of grazing dairy cows. / Constraints to intake imposed by offering sheep access to only one feed were overcome by offering a choice between two feeds simultaneously. Within each choice, sheep generally selected the more slowly degradable option. However, when overall NDF intake could be maintained at approximately 800g/day, the rapidly degraded feed was preferred. / Dairy cows were able to form associations between flavour and postingestive feedback from rumen propionic acid concentration. Although a dose-dependent response was not observed between the concentration of ruminal propionic acid infusion and preference intensity, there was a correlation between ruminal propionic acid concentration and energy status of the cow. In the subsequent experiment, the comparative effect of propionate supplied in the form of salt (instead of acid) on food preference was confounded by a flavour bias. / Diurnal WSC monitoring of perennial ryegrass cultivars bred in the U.K. for 'typical' and 'high' WSC concentrations, expressed similar concentrations at different times of the day and year when grown in northern Victoria. Consequently, in a test of preference between the cultivars, cows showed only slight preference that was not based on WSC concentration. In other choices between adjacent monocultures, cows selected a mixed diet of 62% white clover and 38% ryegrass. / It was concluded that the ideal diet from the animals' perspective is influenced by the rumen propionic acid concentration and the energy status of the animal. Further, an important priority for the ruminant is to maintain an adequate supply of structural carbohydrates to the rumen. Further work is needed to identify the benefits of feeding pasture with higher WSC, but this might be a difficult objective under Australian field conditions until plant material becomes available that more reliably expresses high WSC.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Steven J. Keeley / Non-structural carbohydrates (NSC) are important for plant health and recovery from stress. Controlled-release N sources may moderate turfgrass vegetative growth, thereby maximizing NSC levels. Three studies were conducted to determine the effect of N source/timing on NSC levels, turfgrass visual quality, and color of ‘Midlawn’ bermudagrass and turf-type tall fescue. Additionally, the effect on low temperature tolerance of bermudagrass and brown patch incidence on tall fescue was investigated. Nitrogen sources included two polymer-coated ureas (PCU), a polymer-sulfur coated urea (SCU) and urea formaldehyde (UF). Total annual N was applied in either late summer or spring for bermudagrass, and either late summer or split between late summer and spring for tall fescue. Urea, applied at traditional timings, was a control in all studies. NSC status was determined at regular intervals by extracting two cores from each plot, defoliating, and measuring regrowth in a dark growth chamber. Turfgrass color, visual quality and brown patch incidence were rated monthly during the growing season. Bermudagrass low temperature tolerance was evaluated by subjecting plugs to a freezing regime and evaluating regrowth. Over the 2-yr study, N source did not have a significant effect on bermudagrass or tall fescue NSC levels, color, or visual quality. Timing of application, by contrast, did have a significant impact. For bermudagrass, August-applied N resulted in higher overall NSC levels and improved fall color. For tall fescue, split Sept/March applications improved color; but split Sept/ May applications reduced NSC compared to a single Sept application. Brown patch incidence was unaffected by N source or timing, though disease pressure was low. Timing of PCU application did not affect low temperature tolerance of bermudagrass, but PCU improved low temperature survival compared to urea.

Darbo tikslas - įvertinti daugiametės svidrės (Lolium perenne L.) ir nendrinio dryžučio (Phalaris arundinacea L.) drėgnio ir morfologinių dalių santykio kaitos, cheminių medžiagų (lignino, struktūrinių, nestruktūrinių angliavandenių, baltymų) kaupimosi dėsningumus augalų biomasėje ir skirtingose augalo morfologinėse dalyse priklausomai nuo augalų vystymosi tarpsnio bei vandenyje tirpių angliavandenių (VTA) koncentracijos dinamiką dienos bėgyje. / The objective of this study was to evaluate the changes in moisture content, morphological parts ratio, regularities of chemical components (protein, lignin, structural and non-structural carbohydrates) accumulation in plant biomass and different morphological parts of perennial ryegrass (Lolium perenne L.) and reed canary grass (Phalaris arundinacea L.) depending on plant development stages and to compare diurnal variation of water soluble carbohydrate (WSC) concentrations in above-ground dry matter in the two perennial grass species tested.

Patterns of woody-plant mortality have been linked to global-scale environmental changes, such as extreme drought, heat stress, more frequent and intense fires, and episodic outbreaks of insects and pathogens. Although many studies have focussed on survival and mortality in response to specific physiological stresses, little attention has been paid to the role of genetic heritability of traits and local adaptation in influencing patterns of plant mortality, especially in non-native species. Tamarix spp. is a dominant, non-native riparian tree in western North America that is experiencing dieback in some areas of its range due to episodic herbivory by the recently introduced northern tamarisk leaf beetle (Diorhabda carinulata). We propose that genotype x environment interactions largely underpin current and future patterns of Tamarix mortality. We anticipate that (i) despite its recent introduction, and the potential for significant gene flow, Tamarix in western North America is generally adapted to local environmental conditions across its current range in part due to hybridization of two species; (ii) local adaptation to specific climate, soil and resource availability will yield predictable responses to episodic herbivory; and (iii) the ability to cope with a combination of episodic herbivory and increased aridity associated with climate change will be largely based on functional tradeoffs in resource allocation. This review focusses on the potential heritability of plant carbon allocation patterns in Tamarix, focussing on the relative contribution of acquired carbon to non-structural carbohydrate (NSC) pools versus other sinks as the basis for surviving episodic disturbance. Where high aridity and/or poor edaphic position lead to chronic stress, NSC pools may fall below a minimum threshold because of an imbalance between the supply of carbon and its demand by various sinks. Identifying patterns of local adaptation of traits related to resource allocation will improve forecasting of Tamarix population susceptibility to episodic herbivory.

An understanding of ecosystem-level carbon (C) sequestration, or net ecosystem production (NEP), requires the separation of heterotrophic, microbial respiration (RH) from autotrophic, root-derived respiration (RA) as the components of RS (i.e., NEP = NPP - RH). However, separating these two sources in situ has been problematic since they are closely coupled. This study utilizes two similarly aged Pinus taeda L. stands, 8 and 9 years-old, aimed at quantifying these two respiration components through in-situ root severing. In order to use root-severing treatments to separate RS into RH and RA components, confirmation of carbohydrate depletion coupled to RA decline is crucial. This study evaluated the changes in CO2 flux rates and carbohydrate supply upon root severing in Pinus taeda L. using a controlled laboratory validating a two-part field study. The first field study used root-severing cores to test in-situ if respiration components can be attained based on the depletion of carbohydrate supply. The second field study was aimed at how future changes in climate might affect the ability of forests to store C and how modern forestry practices might affect changes and was conducted over the course of two installations, spring and summer 2012. In this study we examined the effects of fertilization (0 and 100.9 kg N ha-1 ) and throughfall reduction (0 and -30%) on total soil respiration (RS) as well as the heterotrophic contribution to RS, in a fully replicated (n=4), 2x2 factorial design. In the controlled lab experiment RS and RA declined by 86% and 95% respectively by the end of an 86 day trial and NSC carbohydrates declined by 60% for soluble, 29% for insoluble, and 43% for total (soluble + insoluble). The decline of RA was highly correlated to with the decline of NSC’s at 0.90, 0.69 and 0.93 for soluble, insoluble and total, respectively. The companion field study revealed a mean decrease 21±0.5% of over the final three dates when severed root respiration stabilized. In the second study, testing throughfall reduction and fertilization levels there were no fertilization by throughfall reduction interactions on the contribution of RH to RS in either the spring or summer; however, the main effect of throughfall reduction was significant in the spring. During the spring, the mean contribution of RH to RS for ambient throughfall plots was 96±6.4%, while the mean contribution under throughfall reduction was 68±1.9%. During the summer, there were no differences among treatments and the overall contribution of RH to RS was 78±1.6%. Collectively, both of these studies revealed that the severing of roots from their primary energy source and the subsequent depletion of stored NSC that the use of in-situ methods allows for the quantification of soil respiration components RA and RH. Using these estimates to model NEP in the short-term can be variable by season, however, long-term monitoring may simplify future NEP modeling scenarios / Master of Science

As funções metabólicas dos bubalinos ainda não estão bem descritas, como em outros ruminantes e há carência de informação sobre o comportamento digestivo. A sincronização da degradação ruminal de proteína e amido propõe incrementar a produção de proteína microbiana no rúmen e a eficiência de utilização de energia, uma vez que as bactérias ruminais necessitam destes dois elementos disponíveis simultaneamente. Quatro búfalos fistulados no rúmen foram utilizados com objetivo avaliar os efeitos de dietas com diferentes níveis de milho em grãos moídos (0, 22, 37 e 49% na MS) em substituição ao feno de coast-cross, com ênfase na relação proteína:carboidratos não estruturais (1,02; 0,39; 0,30; 0,26), sobre o metabolismo ruminal. Os seguintes parâmetros foram avaliados: ingestão de matéria seca (IMS); degradabilidade da matéria seca e fibra em detergente neutro do feno de coast-cross e da matéria seca e proteína bruta do milho em grãos moído; concentração de amônia; produção de ácidos graxos voláteis (acético, propiônico e butírico); taxa de passagem de líquido; volume ruminal e pH no rúmen. Os animais foram delineados em Quadrado Latino (4x4). Houve aumento linear na IMS com aumento de milho em grãos na dieta. Foram observadas diferenças no metabolismo ruminal envolvendo a produção de ácidos graxos voláteis, pH, taxa de passagem do líquido ruminal e volume do rúmen entre os tratamentos e pouca influência dos tratamentos na produção de amônia e na cinética de degradabilidade ruminal. Os resultados permitiram concluir que, no geral, os bubalinos apresentam boa capacidade tamponante no rúmen com ligeira queda do pH com aumento da ingestão de milho em grãos moídos e que provavelmente os microrganismos ruminais dos búfalos têm boa capacidade em se adaptar a ambientes ruminais com diferentes relações PB:CNE. / The metabolic functions of the buffaloes not yet are well described, as in other ruminants and have information lack on the digestive behavior. The synchronization of the ruminal degradation of protein and starch considers to increase the rumen microbial protein production and the efficiency of energy use, since the rumen bacteria needs of these two available elements simultaneously. Four rumen fistulated buffalos were used with objective to evaluate the effect of diets with different levels of ground grain corn (0, 22, 37 and 49% in the DM) in substitution to the coast-cross hay, with emphasis in the relation protein:no structural carbohydrates (1,02; 0,39; 0,30; 0,26) on the ruminal metabolism. The following parameters had been evaluated: dry matter intake (DMI); DM and NDF degradability of DM and NDF of the coast-cross hay and DM and CP of the ground grain corn; ammonia concentration; production of volatile fatty acids (acetic, propionic and butyric); outflow rate; ruminal volume and rumen pH. The animals were delineated in Latin Square (4x4) experiment. There was linear increase in the DMI with increasing level ground grain corn in the diet. Differences in the ruminal metabolism were observed involving the production of acid VFA, pH, liquid outflow rate and rumen volume among the treatments and small influence of the treatments in the ammonia production and the kinetic of ruminal degradability were observed. The results had allowed to conclude that, in the general, the buffaloes present good rumen buffering capacity with light fall of pH with increasing of the ingestion ground grain corn and that probably the microorganisms in the rumen of the buffalos have good capacity to adapt in the environments with different relations CP:NSC.

As funções metabólicas dos bubalinos ainda não estão bem descritas, como em outros ruminantes e há carência de informação sobre o comportamento digestivo. A sincronização da degradação ruminal de proteína e amido propõe incrementar a produção de proteína microbiana no rúmen e a eficiência de utilização de energia, uma vez que as bactérias ruminais necessitam destes dois elementos disponíveis simultaneamente. Quatro búfalos fistulados no rúmen foram utilizados com objetivo avaliar os efeitos de dietas com diferentes níveis de milho em grãos moídos (0, 22, 37 e 49% na MS) em substituição ao feno de coast-cross, com ênfase na relação proteína:carboidratos não estruturais (1,02; 0,39; 0,30; 0,26), sobre o metabolismo ruminal. Os seguintes parâmetros foram avaliados: ingestão de matéria seca (IMS); degradabilidade da matéria seca e fibra em detergente neutro do feno de coast-cross e da matéria seca e proteína bruta do milho em grãos moído; concentração de amônia; produção de ácidos graxos voláteis (acético, propiônico e butírico); taxa de passagem de líquido; volume ruminal e pH no rúmen. Os animais foram delineados em Quadrado Latino (4x4). Houve aumento linear na IMS com aumento de milho em grãos na dieta. Foram observadas diferenças no metabolismo ruminal envolvendo a produção de ácidos graxos voláteis, pH, taxa de passagem do líquido ruminal e volume do rúmen entre os tratamentos e pouca influência dos tratamentos na produção de amônia e na cinética de degradabilidade ruminal. Os resultados permitiram concluir que, no geral, os bubalinos apresentam boa capacidade tamponante no rúmen com ligeira queda do pH com aumento da ingestão de milho em grãos moídos e que provavelmente os microrganismos ruminais dos búfalos têm boa capacidade em se adaptar a ambientes ruminais com diferentes relações PB:CNE. / The metabolic functions of the buffaloes not yet are well described, as in other ruminants and have information lack on the digestive behavior. The synchronization of the ruminal degradation of protein and starch considers to increase the rumen microbial protein production and the efficiency of energy use, since the rumen bacteria needs of these two available elements simultaneously. Four rumen fistulated buffalos were used with objective to evaluate the effect of diets with different levels of ground grain corn (0, 22, 37 and 49% in the DM) in substitution to the coast-cross hay, with emphasis in the relation protein:no structural carbohydrates (1,02; 0,39; 0,30; 0,26) on the ruminal metabolism. The following parameters had been evaluated: dry matter intake (DMI); DM and NDF degradability of DM and NDF of the coast-cross hay and DM and CP of the ground grain corn; ammonia concentration; production of volatile fatty acids (acetic, propionic and butyric); outflow rate; ruminal volume and rumen pH. The animals were delineated in Latin Square (4x4) experiment. There was linear increase in the DMI with increasing level ground grain corn in the diet. Differences in the ruminal metabolism were observed involving the production of acid VFA, pH, liquid outflow rate and rumen volume among the treatments and small influence of the treatments in the ammonia production and the kinetic of ruminal degradability were observed. The results had allowed to conclude that, in the general, the buffaloes present good rumen buffering capacity with light fall of pH with increasing of the ingestion ground grain corn and that probably the microorganisms in the rumen of the buffalos have good capacity to adapt in the environments with different relations CP:NSC.

This diploma thesis examines influence of content of leaf nitrogen and non-structural carbohydrates on Rubisco activity and its content under impact of ambient (A = 385 µmolCO2 mol-1) and elevated (E = 700 µmolCO2 mol-1) concentrations of carbon dioxide in needles of Norway spruce (Picea abies L.). The Rubisco activity was determined spectrophotometrically, the Rubisco content by using SDS-PAGE, the content of non-structural carbohydrates by using the anthron method and total leaf nitrogen was determined by using the Kjeldahl method. The Rubisco activity in needles of Norway spruce did not show acclimation on elevated concentration of carbon dioxide, but the activity was elevated concentration of carbon dioxide stimulated during the growing season. The acclimation was proved by Rubisco content, its content was significantly lower in needles cultivated under elevated carbon dioxide. Content of total leaf nitrogen was statistically significantly lower in needles of Norway spruce cultivated under elevated carbon dioxide then in needles cultivated under ambient concentration of carbon dioxide. On the contrary, the content of non-structural carbohydrates was significantly higher in needles cultivated under elevated concentration of carbon dioxide then in variant A. Seasonal changes of Rubisco content depended on content of non-structural carbohydrates, the Rubisco content decreased with increasing content of non-structural carbohydrates. No dependence was detected between seasonal changes of the total leaf content and the Rubisco content.

Dans le but de progresser dans la compréhension des fonctionnements carboné et azoté des arbres, ce travail a consisté à étudier les effets de l’âge sur les dynamiques saisonnières ainsi que sur les quantités des réserves carbonées et azotées de l’arbre.Cette étude a été réalisée in situ chez une chronoséquence composée de trois classes d’âge de chênes sessiles (8, 20 et 150 ans). La dynamique saisonnière des concentrations en composés carbonés et azotés de réserve a été étudiée durant une année chez les jeunes branches et les racines moyennes et fines, en ciblant les points d’échantillonnage sur des dates phénologiques et de croissance clés de l’arbre. La quantification des réserves a été permise grâce à l’estimation des biomasses vivantes des différents organes de l’arbre. L’étude des effets de l’âge sur les quantités des réserves carbonées et azotées et leur répartition au sein de la biomasse a été réalisée à l’échelle de l’arbre dominant et à l’échelle du peuplement.Avec l’âge, la dynamique saisonnière de formation des réserves carbonées est modifiée. Les jeunes arbres allouent préférentiellement le C à la croissance, le stockage n’ayant lieu qu’à la fin de la croissance du bois. Chez les arbres matures, la croissance et le stockage se font conjointement au cours de la saison de végétation. La dynamique saisonnière des réserves azotées n’est globalement pas différente entre les trois classes d’âge : le minimum des réserves est observé en été et le maximum après le jaunissement. Les arbres matures ont des concentrations en acides aminés plus importantes que les deux autres classes d’âge, ce qui pourrait être relié à une plus grande biomasse de racines fines et un plus fort taux de mycorhization au stade mature, permettant une meilleure exploration du sol et une meilleure nutrition minérale.Les quantités de réserves carbonées et azotées de l’arbre dominant et du peuplement augmentent avec l’âge. La répartition des réserves dépend principalement de celle de la biomasse vivante entre les différents organes. Le tronc stocke ainsi la majorité des composés carbonés et azotés non structuraux de l’arbre et du peuplement, quel que soit l’âge. Toutefois, les concentrations en composés de réserve ont un effet non négligeable sur la localisation des réserves au sein de l’arbre car la répartition des réserves carbonées et azotées peut être différente de celle des biomasses vivantes. Par cette étude, nous mettons en évidence que l’allocation des composés carbonés non structuraux au stockage dans les grosses racines et les branches augmente progressivement avec l’âge de l’arbre.Les résultats de cette étude permettent ainsi de montrer une évolution dans la gestion du C et de l’N avec l’âge de l’arbre. / In order to progress in the comprehension of tree carbon and nitrogen functioning, this work studies tree age effects on seasonal changes and quantities of carbon and nitrogen reserves.This study was performed in situ in a chronosequence of three different ages of sessile oaks (8, 20 and 150 years old). Seasonal dynamics of carbon and nitrogen compound concentrations was studied for one year in young branches and fine and medium roots, at key phenological and growth stages. The reserve quantification was possible thanks to the estimation of the living biomass of the tree different organs. The study of age effects on carbon and nitrogen reserve quantities and their distribution within the tree biomass was realized at the dominant tree scale and the stand scale.Seasonal dynamics of carbon reserve formation changes with ageing. Young trees allocate preferentially C to growth; C storage begins only after the end of wood growth. In mature trees, growth and storage occur at the same time during the vegetative period. Seasonal dynamics of nitrogen reserves is overall not different between the three age classes: the minimum nitrogen reserve is observed in summer and the maximum one after yellowing. Mature trees have higher amino acid concentrations, which could be explained by a higher fine root biomass and a higher mycorrhization rate at mature stage, allowing a better soil exploration and mineral nutrient.Carbon and nitrogen reserve quantities of the dominant tree and stand increase within age. Reserve distribution mainly depends on the living biomass distribution between the different organs. Stem stocks the majority of tree and stand carbon and nitrogen reserves for the three age classes. However carbon and nitrogen compound concentrations have an important effect on the reserve localization in tree because carbon and nitrogen reserve distribution can be different from the living biomass one. With this study, we show that carbon compound allocation to storage in coarse roots and branches increase progressively with tree age.The results of this study highlight an evolution in C and N management with tree age.

This diploma thesis deals with dynamic of accumulation of non-structural carbohydrates and activity of Rubisco enzyme at elevated concentration of CO2 on beech (Fagus sylvatica L.). Three years old seedlings of beech were cultivated in minisphere with ambient (385 µmol•mol-1, variant A), and with elevated concentration CO2 (700 µmol•mol-1, variant E) for four months. In every variant the first half of plants was fertilized by nitrogen (variant N+) and the second half was control (variant N-). Plants used for experiment were at first adapted for darkness for 12 hours. Subsequently tested leaves were cut off, leafstalk including short segment of branch (approximately 1 cm) was inserted into 0.7 M solution of sucrose (variant S) or water (variant V) and exposed to radiation 200 mol•m-2•s-1 for 0, 30, 60, 120, 180 minutes. Then leaf area and fresh mass of leaf blade were established, samples were fixed in liquid nitrogen and stored in deep freezer to analysis in –70 °C. Rubisco content was determined by SDS-PAGE method, Rubisco activity spectrofotometrically and content of non-structural carbohydrates by anthrone method and HPLC method. Rubisco content was significantly lower in the N- variant than in N+ variant. Rubisco content was also significantly lower in E than in A variant, which is an evidence of down-regulation. Rubisco activity is moderately stimulated at E variant with time, but differences between variant A and E are not statistically significant. Influence of sucrose feeding to Rubisco activity was not proved. Significant differences were detected by anthrone method in non-structural carbohydrates content between variants S and V, but not between variants A and E. Statistically significant increase of sucrose content with time was detected by HPLC method at variant AS, but not at variant ES.