Browsing by Subject "diet"
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Item Associations between hydrological connectivity and resource partitioning among sympatric gar species (Lepisosteidae) in a Texas river and associated oxbows(2009-05-15) Robertson, Clinton RayThe middle Brazos River, located in east central Texas, is a meandering lowland river that contains many oxbow lakes on its floodplain. Flood dynamics of the Brazos River are aseasonal, and faunal exchange during lateral connections of the main river channel and oxbows is pulse-like and only occurs during floods that may be months or years apart. Patterns of resource use among sympatric gar species (Lepisosteus oculatus, L. osseus, and Atractosteus spatula) associated with river-floodplain connectivity was studied for a period of two years (May 2003 to May 2005). The first year was relatively dry yielding few lateral connections, whereas the second year was relatively wet resulting in more frequent lateral connections. This study focused on habitat and diet partitioning among the three gar species in oxbow habitats with different connection frequencies and an active river channel site. Overall, 684 gars were collected with experimental gillnets: 19 A. spatula (alligator gar), 374 L. oculatus (spotted gar), and 291 L. osseus (longnose gar). There was strong partitioning of habitat between spotted and longnose gars, in which 98% of spotted gars were captured in oxbow habitats and 84% of longnose gars were captured in the river channel. Hydrology did not appear to affect habitat partitioning, although longnose gar abundance significantly increased in oxbows during the wet year. Diet overlap was high between spotted and longnose gars. Temporal variation in diet was significantly influenced by flood pulses that connected oxbows with the river channel, and which allowed predators and their prey to move between habitats.Item Blue Crab Population Ecology and Use by Foraging Whooping Cranes on the Texas Gulf Coast(2012-02-14) Greer, Danielle MarieIn 2002, a proposal was submitted to divert water from the confluence of the Guadalupe and San Antonio Rivers to San Antonio, Texas. To investigate the potential impacts of diverting water from the Guadalupe Estuary, my research focused on the foraging ecology of the crane and population ecology of the blue crab, a documented crane food. During winters 2004-2005 and 2005-2006, I examined diets and optimal foraging patterns of territorial adult cranes at Aransas National Wildlife Refuge, Texas. To identify foods of greatest benefit to cranes, I used currencies of optimization to evaluate foraging gain, cost, and efficiency. Foraging benefit differed among foods, depending on the foraging currency used and resource targeted (e.g., energy). Wolfberry fruit, snails, and insects were consumed in the highest quantities, required the least foraging effort, and were generally associated with the highest foraging efficiency. Blue crabs and clams were important sources of protein and biomass. During September 2003-October 2005, I used novel artificial settlement substrates and modified methods of standard deployment to investigate the spatio-temporal patterns of blue crab terminal settlement and recruitment rates. Monitoring rates in shallow bay habitat and ponds of the interior salt-marsh revealed megalopal crabs were developmentally advanced when arriving to study sites and the extent to which young crabs infiltrated the salt-marsh increased with age. Such findings suggested sites represented optimal terminal settlement habitat and consequently critical nursery habitat. Model selection indicated water temperature before and during embryonic development was the best predictor of megalopal settlement, whereas juvenile recruitment was most influenced by recent precipitation. I studied the size-specific abundance patterns of blue crabs in and around mature salt-marsh. Using drop-trapping and throw-trapping methods, I collected monthly samples in several habitats during October 2004-March 2006. Interior-marsh habitats contained fewer but larger crabs than bay habitat. Crabs contributing greatest to biomass were smallest (11-30 mm carapace-width) in bay habitat, larger (31-80 mm) along interior-marsh pond edges, and largest (41-130 mm) in interior-marsh open water. Model selection revealed crab density was most influenced by micro-site characteristics (habitat, water column structure type and structural complexity). Overall, shallow bay provided important nursery habitat for young blue crabs and interior marsh ponds were important for dispersing juvenile and adult crabs.Item Dietary supplementation of omega-3 fatty acids and subsequent effects on fresh, cooled, and frozen seminal characteristics of stallions(2009-05-15) Grady, Sicilia TatianaThe use of cooled and frozen/thawed semen offers many advantages to breeders. However, many stallions produce spermatozoa that are unable to endure the stresses of cooling/storage and freezing/thawing. Improving the quality and viability of equine spermatozoa via appropriate dietary manipulation could make these stallions commercially viable for cooling or cryopreservation. To evaluate whether spermatozoa quality and viability can be improved by supplementation of omega-3 fatty acids, and if improvements can be made by altering the sources of these fats, nine miniature stallions were placed into 1 of 2 treatment groups and fed either a fish- or algae/flaxseed-based supplement which was added to the basal concentrate. Motion characteristics, membrane integrity and morphology of spermatozoa in fresh, cooled/stored (24 and 48 h), and frozen/thawed semen samples were analyzed. When comparing spermatozoa obtained from stallions in each treatment, no differences were found (P > 0.05) in motility, percentage of membrane intact spermatozoa, and percentage of morphologically normal spermatozoa of stallions. Overall, omega-3 supplementation did not appear to have a beneficial effect on offsetting the harmful effects of the cooling and freezing processes. However, when analyzing the data of one stallion that had < 40% progressive motility (PMOT) after 24 h of cooling and storage, a significant increase was observed in total motility, and progressive motility of fresh and 24 h cooled/stored spermatozoa was observed when supplemented with the fish-based supplement. Thus, omega-3 fatty acid supplementation may be most beneficial for stallions that produce lower quality ejaculates. However, further studies should be conducted, with a larger sample size, in order to substantiate these findings.Item Effect of Trace Mineral Supplementation on Gastric Ulcers in Exercising Yearling Horses(2010-10-12) Hayes, Alexa DawnEquine gastric ulcer syndrome (EGUS) has been reported to occur in 40% to over 90% of horses across multiple equestrian disciplines. The objective of this study was to evaluate the effect of trace mineral supplementation on gastric ulcers in exercising yearling horses. Twenty-one Quarter Horse yearlings, 15 to 18 mo of age, were randomly assigned to 1 of 3 treatment groups. The control group received no supplemental trace minerals, the inorganic group received supplemental sulfated trace minerals, and the organic treatment received supplemental amino acid complexed trace minerals. The trial consisted of 3 consecutive 28-d periods, separated by 5 d of diet acclimation. The basal ration included a 14% CP textured concentrate, with coastal Bermudagrass hay fed in Periods 1 and 3 and alfalfa consumed in Period 2. In Periods 1 and 2, horses were exercised on a mechanical horse-exerciser, but were lunged or underwent training in an undergraduate course in Period 3. At the end of each period, horses were transported for 6 h, 5 d before being endoscopically examined to assign ulcer scores. Data were analyzed as repeated measures using the mixed procedure of SAS, with the model including fixed effects of treatment, period, and their interaction (SAS 9.2). All P-values < 0.05 were considered significantly different. Baseline EGUS scores were not different among treatment groups, with a mean of 2.1. There was no effect of treatment in any period, or a period by treatment interaction. There was a significant period effect (P < 0.01). Mean ulcer scores in Periods 1, 2, and 3 were significantly lower than baseline, with mean scores of 1.5, 1.0, and 1.5, respectively. There was a tendency (P=0.06) for mean ulcer scores to be lower in Period 2 than in Periods 1 and 3, which were not different. Average daily intakes of Zn, Mn, Cu, and Co were significantly higher in the organic and inorganic than control horses (P < 0.0001). Under the conditions of this study, trace mineral supplementation did not affect gastric ulcer appearance and severity. However, it is possible that dietary and management alternatives, such as hay and concentrate types, could be anti-ulcerogenic.Item Evaluation of dietary factors associated with spontaneous pancreatitis in dogs(2009-05-15) Lem, Kristina YvonneThis study estimates the association between dietary factors and spontaneous pancreatitis in dogs. A case-control study was conducted using 198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis. Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatment, length of hospital stay, and discharge status was extracted from medical records for dogs admitted to the Texas A&M University Small Animal Clinic (TAMU SAC) during January 2000 to December 2005. Information on dietary intake, signalment, weight, medical, surgical and environmental history was collected for the same dogs through a telephone questionnaire conducted from November 2006 through January 2007. Descriptive statistics were calculated, tabular analyses performed, and logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Based on information extracted from the medical records, ingesting unusual food (OR=4.3; CI=1.7 to 10.7), ingesting table food (OR=1.5; CI=1.0 to 2.2), or exposure to both of these dietary factors (OR=2.1; CI=1.3 to 3.2) increased the odds of pancreatitis. Collected through the telephone questionnaire, ingesting unusual food (OR=6.1; CI=2.2 to 16.5), ingesting table scraps the week before diagnosis (OR=2.2; CI=1.2 to 3.8) or regularly throughout life (OR=2.2; CI=1.2 to 4.0), and getting into the trash (OR=13.2; CI=2.1 to undefined) increased the odds of pancreatitis. Multivariable modeling estimated the associations of exposure to one or more dietary factors reported through the telephone questionnaire (OR=2.6; CI=1.4 to 5.0), overweight (OR=1.3; CI=0.7 to 2.5), year of diagnosis (OR=3.5; CI=1.9 to 6.5), neuter status (OR=3.6; CI=1.4 to 9.5), non-neuter surgery (OR=21.1; CI=3.3 to 133.9) and an interaction term between neuter status and non-neuter surgery (OR=0.1; CI=0.01 to 0.4). Dietary factors increase the odds of spontaneous pancreatitis in dogs.Item Genetic and dietary effects on the physical properties, assembly and secretion of apoB-containing lipoproteins(Texas A&M University, 2005-11-01) Wang, LiminThe physical properties (i.e., mass, particle diameter and composition) of apolipoprotein B (apoB)-containing lipoproteins (apoB-LP) are a major determinant of atherosclerotic cardiovascular disease (ASCVD) risk. The objective of this research was to investigate how nascent apoB-LP physical properties affect circulating lipoprotein profiles and risk of disease. Relationships between apoB-LP physical properties and arterial plaque formation in four genotypes of mice with apoB isoform specific clearance defects were investigated. Multivariate statistical analysis found that arterial lesions were most closely related to genetic background and apoB concentration related to delayed clearance rate. For defining the dietary effects on circulating lipoprotein profiles, the physical properties of lipoproteins in hamsters fed high-carbohydrate diets containing either 60% fructose or 60% cornstarch for 2 wk were studied. Fructose increased very low-density lipoprotein (VLDL) particle diameter and decreased low-density lipoprotein (LDL) particle diameter. Elevations in all high-density lipoprotein (HDL) fractions were observed in the fructose-fed group. Further investigation was made of whether changes to the physical properties in circulating lipoproteins resulted from changes to nascent particles in the assembly and secretion processes. Intermediate particles used for lipoprotein assembly were isolated from rough endoplasmic reticulum of hamster liver, and nascent VLDL were isolated from plasma after Triton WR-1339 injection of hamsters. A large, TG-rich apoB-deficient particle and a small, lipid-poor apoB-containing particle were isolated in each dietary setting. The diameter of first-step particles was larger in fructose feeding, which indicated that apoB degradation decreases and provides the basis for apoB oversecretion. Fructose feeding significantly increased the concentrations recovered from liver for these two particles and for nascent particles compared with chow or starch feeding. Collectively, these results demonstrate: 1) genetic factors can dictate metabolism, and metabolic conditions can critically affect the physical properties and further atherogenicity of apoB-LP; 2) changes in physical properties of circulating apoB-LP are derived from changes to the nascent particles; and 3) dietary factors can influence the assembly, secretion, and metabolism of apoB-LP. The findings of the research may provide a metabolic basis for the recognition of new targets that could regulate apoB-LP metabolism to prevent and treat ASCVD.Item Relationships between psychosocial factors and adherence to diet and exercise in adults with type 2 diabetes: A test of a theoretical model(2007-05-21) Elizabeth Gressle Tovar; Michele Clark, RN, PhD; Susan Weller, PhD; Regina Lederman, RN, PhD; Hoang Nguyen, PhD; Carrie Jo Braden, RN, PhDIntroduction: Cardiovascular disease (CVD) is the leading cause of premature death among people with diabetes. Diet and exercise adherence are\r\nimportant diabetes self management behaviors that can reduce CVD risk; unfortunately, adherence rates are low among diabetics. Improved understanding of psychosocial factors related to diet and exercise adherence among adults with\r\ntype 2 diabetes can improve strategies to reduce CVD morbidity and mortality in this population.\r\n Purpose: 1) Evaluate psychometrics of the Health Beliefs related to Cardiovascular Disease scale (HBCVD) which measures perceived susceptibility to and severity of heart attack or stroke and perceived benefits of and barriers to\r\ndiet and exercise; 2) Explore relationships between selected bio-psychosocial factors and diet and exercise adherence; and 3) Evaluate the ability of a theoretical model integrating the Health Belief Model (HBM) and Stages of Change Model (SOC) to explain diet and exercise adherence.\r\n Methods: The study design was a descriptive correlational cross section using a convenience sample of 212 adults with type 2 diabetes who completed a series of questionnaires measuring study variables. Outcome variables measured were diet and exercise adherence scores. Predictor/independent variables included knowledge related to CVD risk, cues to action, health beliefs, stage of change, social support, depression, comorbidity, diabetes duration, and\r\nsocioeconomic status. Relationships among model variables were explored using analysis of variance and simple and multiple regression techniques.\r\n Results: The HBCVD demonstrated evidence of validity and reliability, although an improved barriers subscale is recommended. The theoretical model was not supported, although significant paths between model variables were identified. The best model to predict diet included diet stage, susceptibility, self efficacy, social support, and age. The best model to predict exercise included\r\nexercise stage, self efficacy, and social support. Models including HBM and SOC provided greater explanatory power for diet and exercise adherence than either model alone. Susceptibility, barriers, and self efficacy varied significantly across\r\nstages of change. Significant group differences were found among model variables. Participants with depressive symptoms and the least education had lower diet and exercise adherence scores. Younger age and unemployment were also associated with lower diet adherence.\r\n