A series of experiments were carved out to study the effect of dietary enzyme inclusion or flaxseed processing on feeding value of flaxseed for broilers. The feed enzymes tested containing xylanase activities failed to produce any positive performance response when used in a 10% flaxseed diet with manufacturer recommended dosage for broilers (D 1 to 21). / Autoclaving of flaxseed at 16.5 kg/cm2 and 120°C for 15 min slightly improved the performance of young broilers fed a 10% flaxseed diet. This improvement was not observed at lower temperature and shorter period of autoclaving, but was magnified at higher flaxseed level. Autoclaving, microwave roasting, pelleting significantly (P < 0.05) reduced HCN content in flaxseed. The greatest HCN reduction was observed with repeated pelleting (54.9%) and microwave roasting (83.2%), from its 377 mg/kg of raw flaxseed. / When tested with roosters, flaxseed processing effectively increased ME values, dry matter, and ether extract utilization. The raw flaxseed TME and TMEn of 3343 and 3225 kcal/kg, respectively, was significantly (P < 0.01) increased by repeated pelleting (44%) and microwave roasting (32%). It was the result of significant improvement (P < 0.05) of EE utilization by the relevant processing. These improvements had a similar effect on total FA and linolenic acid utilization. / The processing method and flaxseed level had a very significant effect on deposition of total T-3 FAs in breast and thigh meat (P < 0.001) of 40 days old broilers. The highest level of T-3 FAs in muscle lipids of 23.04% and 26.46% for breast and thigh, respectively, was achieved with the highest flaxseed level (14% in days 1 to 21 days, and 17% in days 22--40) and pellet-then-mash processing, which lead to low T-6/T-3 ratios of 0.81 and 0.80 in breast and thigh muscle lipid, respectively. The proper flaxseed processing allowed more flaxseed (up to 12%) to be included in broiler diets without obvious growth depression, while achieving the higher desired T-3 FAs deposition in meat.

<p>Several abnormal conditions, including some cancers, have been associated with changes in the membrane lipid and FA composition. Dietary fat serves as a major source of lipids and FA, particularly the polyunsaturated fatty acids (PUFA), n-6 and n-3. High intakes of n-6 PUFA have been linked to the development of colon cancer in association with low n-3 PUFA intake. Therefore understanding the differences in the lipid and FA profiles between cancer and normal cells in the colon, and the role diet plays in these factors may be invaluable in understanding their role in carcinogenesis. This study compares the lipid profile of azoxymethane (AOM) induced colon polyps to that of the surrounding mucosa tissue in rats fed a diet high in n-6 PUFA. Male Fischer rats were fed the AIN-76A diet containing sunflower oil that has high n-6 PUFA content for a period of nine months. Results indicate that the lipid and FA content of the colon polyps differs significantly from the surrounding mucosa. Colon polyps had an increase in membrane phopholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Changes in membrane fluidity were indicated by the decrease (p&lt / 0.05) in the PC/PE and cholesterol/phospholipids (chol/PL) ratios, and increase (p&lt / 0.05) in the polyunsaturated FA/saturated FA (P/S) ratio. Metabolism of FA was significantly altered in the polyps favouring n-6 FA metabolism and the production of prostaglandin E2. No clear indication of impaired &Delta / 6-desauturase enzyme activity was noticed. Increases in the n-6 PUFA content could be a reflection of the dietary FA intake that increases FA incorporation in the polyps. Changes in the FA parameters of the polyps, particularly an increase in C20:4n-6 and the n6/n3 ratio have been shown to contribute to the rapid growth of cancer tissue. These lipid changes associated with the development of colon polyps could provide unique targets for developing strategies in chemoprevention by dietary manipulation.</p>

Current trends toward warmer air temperatures and longer ice free seasons in Hudson Bay are expected to cause changes in Arctic marine ecosystem dynamics. Ringed seals (Phoca hispida) will likely experience changes in levels of predation, competition, and prey availability. The purpose of this thesis was to investigate seasonal, inter-annual, and spatial variation in Hudson Bay ringed seal feeding ecology. Fatty acid composition, δ15N, and δ13C varied significantly by season, suggesting seasonal changes in foraging habitat and diet. Spatial differences in ringed seal stable isotope ratios occurred between western and eastern Hudson Bay, and there was a strong relationship between spring air temperature and δ15N. Peak δ15N occurred within a range in spring air temperatures between approximately -5°C and -2°C. I propose that the high δ15N observed in ringed seals within this temperature range is indicative of relatively greater importance of capelin (Mallotus villosus) in the ringed seal diet.

Trophic ecology is a key component in describing patterns of variation between and within populations, particularly in Arctic marine systems wherein climate change is impacting food webs. This thesis investigates the trophic ecology of Arctic char (Salvelinus alpinus) in the Cumberland Sound region using a multi-indicator approach. My data show trophic niche differences between resident and anadromous ecotypes and evidence for estuarine feeding by residents. I document a shift in the marine diet of Arctic char from zooplankton to capelin (Mallotus villosus) – a novel prey species in this region – that has occurred in less than a decade. Changes in Arctic char growth imply population-level effects of this shift; however, more research is required. Finally, I find lipid effects on δ13C and lipid-extraction effects on δ15N and δ34S for Arctic char muscle tissue. Lipid-correction models did not provide adequate δ13C estimates; thus, chemical extraction or ecotype-specific validation of models is recommended.

The discovery of new immunosuppressive drugs has resulted in an improvement of short-term graft survival. Despite this achievement, long-term cardiac allograft survival has not been correspondingly improved. Cyclosporine A (CsA), an effective immunosuppressive drug, has been shown to increase the risk of hyperlipidemia, hypertension, kidney injuries and chronic rejection despite its extensive use in the clinical setting. Therefore, these side-effects of CsA, may further contribute to graft failure over long-term. Early studies have shown that fish oil may reduce side-effects of CsA. These beneficial effects of fish oil may be related to n-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Flaxseed oil is another major source of an n-3 FA, namely α-linolenic acid (ALA). However, its impact on heart transplantation has not been fully explored. The current study aimed to investigate whether dietary flaxseed oil and fish oil reduce post-transplant complications and prolong graft function in a rat cardiac allograft model. Male Fischer and Lewis rats were used as donors and recipients, respectively, to generate a heterotopic cardiac allograft model. After transplant, animals were randomly assigned into 3 groups and fed a diet supplemented with: a) 5% w/w safflower oil (control n=7), b) 5% w/w flaxseed oil (n=8) or c) 2% w/w fish oil (n=7) and an intraperitoneal injection of cyclosporine A (CsA) (1.5 mg/kg/d) over 12 weeks. Body weight, blood pressure (BP), plasma levels of lipids, CsA, and select cytokines, fatty acid profile of hearts (native and graft) and liver tissues as well as graft function and chronic rejection features were assessed. Body weight and blood CsA levels were similar among the groups. As compared to controls, both diet treated groups demonstrated a significantly lower systolic blood pressure (SBP) (p<0.001), diastolic blood pressure (pressure (DBP) (p<0.001), mean arterial pressure (MAP) (p<0.001), heart rate (p<0.05), abdominal fat (p<0.05) and plasma levels of macrophage chemoattractant protein-1 (MCP-1) (p<0.05). Moreover, the fish oil group had significantly (p<0.05) lower plasma levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), as compared to the control group. High-density lipoprotein cholesterol (HDL) concentrations were significantly higher (P<0.05) in the flaxseed oil-treated group as compared to the other two groups. Data of this study suggest that both flaxseed oil and fish oil may provide similar biochemical, hemodynamic and inflammatory improvements after heart transplantation; however, these apparent beneficial changes were not accompanied with significant reductions in chronic rejection states or apparent histological evidence of cyclosporine-induced nephrotoxicity in this model.

The aim of this thesis was to investigate how dietary fatty acids affect the risk for cardiometabolic disease, i.e. cardiovascular disease (CVD), type 2 diabetes and obesity. The overall hypothesis was that unsaturated fatty acids and especially the predominant polyunsaturated fatty acid (PUFA) linoleic acid (LA), 18:2n-6, would decrease cardiometabolic risk compared with saturated fatty acids (SFAs), in line with current recommendations to partly replace dietary SFA with PUFA. Papers I and V were observational studies based on the community-based cohort Uppsala Longitudinal Study of Adult Men (ULSAM). Adipose tissue fatty acid composition was determined as biomarker for dietary fat intake. Studies II, III and IV were randomised short-term interventions on human volunteers, in which different dietary fats were provided to the participants. In 71-year-old men, adipose tissue LA and α-linolenic acid (18:3n-3) were associated with insulin sensitivity (euglycaemic clamp), although this association was diminished for LA after adjusting for lifestyle variables. Different SFA displayed divergent associations; only palmitic acid (16:0) was inversely associated with insulin sensitivity (Paper I). In Cox regression analyses, LA was modestly associated with decreased all-cause mortality, but not CVD mortality during 15 years follow-up (Paper V). In a 3+3-week cross-over study on 20 weight-stable volunteers with dyslipidaemia, all foods were provided. A rapeseed oil-based diet distinctly lowered low-density lipoprotein cholesterol and triglycerides compared with a dairy-fat based diet (butter, cream and fatty cheese). Insulin sensitivity or coagulation factors were not affected (Paper II). In a 10-week randomised trial on 67 abdominally obese participants, PUFA (mostly sunflower oil) decreased liver fat compared with SFA (mostly butter) under isocaloric conditions. In individuals considered highly compliant to study diets, lipoproteins were also decreased during the PUFA diet (Paper III). In a 7-week double-blind randomised trial on 41 healthy volunteers, PUFA (sunflower oil) decreased the total:HDL cholesterol ratio compared with SFA (palm oil) during moderate weight gain (1.5 kg) (Paper IV). In conclusion, LA (PUFA) intake is associated with decreased cardiometabolic risk compared with higher SFA intake, overall supporting a beneficial role of non-tropical vegetable oils in place of solid fats in preventing fatty liver and cardiometabolic disorders.

In an effort to determine the relative amount of carbohydrates and free fatty acids (FFA) utilized by trained and untrained men at a submaximal workload and the relationship of selected mitochondrial and glycolytic enzyme activities, six trained and six untrained males were exercised for one hour at 50o of their maximal oxygen uptake (V02 max).Muscle samples were taken from the vastus lateralis in three cyclists and from the gastrocmemius in three runners from each group before and after exercise, and later assayed for succinic acid dehydrogenese, malic acid dehydrogenase, lactic acid dehydrogenase, phosphorylane, and carnitine paLmityltransf erase activities, and glycogen levels. Th e post exercise sample was assayed for glycogen, another was sectioned and stained for glycogen and fiber composition (PAS and-glycerolphosphate dehydrogenase) and from a third coupled mitochondria were isolated to determine 14'CO2 production from oxidation of varied levels of 14C-palmityl-CoA. Blood drawn before, immediately after, and thirty minutes after the exercise was assayed for FFA, glycerol, triglycerides, and glucose levels. Activities of oxidative enzymes (SDH, MDH, and CPT) were significantly higher (2-3 times greater) in the trained individuals than in the untrained group. Glycolytic enzyme activities were higher in the untrained group, probably due to higher fast twitch fiber populations. During exercise, FFA levels rose to the same degree in both groups; however, glycerol levels increased almost five times greater during the exercise in the trained subjects indicating the FFA turnover was much larger in the trained subjects. Blood glucose levels increased by an average of 11 mg% during the exercise in the trained subjects but fell by 8 mg% in the others, suggesting a greater selective uptake by the untrained subjects. Muscle glycogen depletion was 66% greater in the untrained group. These catabolic processes were independent of muscle fiber type, indicating that aerobic training increases those enzyme activities associated with FFA oxidation. Trained individuals are thus able to shift to fatty acids as the primary carbon source for the citric acid cycle, sparing glycogen during submaximal work.

Trophic ecology is a key component in describing patterns of variation between and within populations, particularly in Arctic marine systems wherein climate change is impacting food webs. This thesis investigates the trophic ecology of Arctic char (Salvelinus alpinus) in the Cumberland Sound region using a multi-indicator approach. My data show trophic niche differences between resident and anadromous ecotypes and evidence for estuarine feeding by residents. I document a shift in the marine diet of Arctic char from zooplankton to capelin (Mallotus villosus) – a novel prey species in this region – that has occurred in less than a decade. Changes in Arctic char growth imply population-level effects of this shift; however, more research is required. Finally, I find lipid effects on δ13C and lipid-extraction effects on δ15N and δ34S for Arctic char muscle tissue. Lipid-correction models did not provide adequate δ13C estimates; thus, chemical extraction or ecotype-specific validation of models is recommended.

The discovery of new immunosuppressive drugs has resulted in an improvement of short-term graft survival. Despite this achievement, long-term cardiac allograft survival has not been correspondingly improved. Cyclosporine A (CsA), an effective immunosuppressive drug, has been shown to increase the risk of hyperlipidemia, hypertension, kidney injuries and chronic rejection despite its extensive use in the clinical setting. Therefore, these side-effects of CsA, may further contribute to graft failure over long-term. Early studies have shown that fish oil may reduce side-effects of CsA. These beneficial effects of fish oil may be related to n-3 fatty acids (n-3 FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Flaxseed oil is another major source of an n-3 FA, namely α-linolenic acid (ALA). However, its impact on heart transplantation has not been fully explored. The current study aimed to investigate whether dietary flaxseed oil and fish oil reduce post-transplant complications and prolong graft function in a rat cardiac allograft model. Male Fischer and Lewis rats were used as donors and recipients, respectively, to generate a heterotopic cardiac allograft model. After transplant, animals were randomly assigned into 3 groups and fed a diet supplemented with: a) 5% w/w safflower oil (control n=7), b) 5% w/w flaxseed oil (n=8) or c) 2% w/w fish oil (n=7) and an intraperitoneal injection of cyclosporine A (CsA) (1.5 mg/kg/d) over 12 weeks. Body weight, blood pressure (BP), plasma levels of lipids, CsA, and select cytokines, fatty acid profile of hearts (native and graft) and liver tissues as well as graft function and chronic rejection features were assessed. Body weight and blood CsA levels were similar among the groups. As compared to controls, both diet treated groups demonstrated a significantly lower systolic blood pressure (SBP) (p<0.001), diastolic blood pressure (pressure (DBP) (p<0.001), mean arterial pressure (MAP) (p<0.001), heart rate (p<0.05), abdominal fat (p<0.05) and plasma levels of macrophage chemoattractant protein-1 (MCP-1) (p<0.05). Moreover, the fish oil group had significantly (p<0.05) lower plasma levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), as compared to the control group. High-density lipoprotein cholesterol (HDL) concentrations were significantly higher (P<0.05) in the flaxseed oil-treated group as compared to the other two groups. Data of this study suggest that both flaxseed oil and fish oil may provide similar biochemical, hemodynamic and inflammatory improvements after heart transplantation; however, these apparent beneficial changes were not accompanied with significant reductions in chronic rejection states or apparent histological evidence of cyclosporine-induced nephrotoxicity in this model.

Heat exposure causes several physiological and metabolic alterations. Although lipids are vital in sustaining energy production, heat-induced alterations in lipid metabolism have not been clearly established. CHAPTER 1 reviews the known metabolic alterations resulting from heat stress, with a specific focus on changes in whole-body lipid utilization and plasma lipids. CHAPTER 1also outlines the physiological changes caused by heat stress, and their role in reducing exercise performance. The study presented in CHAPTER 2 has shown that, compared to thermoneutral conditions, NEFA concentrations were 37% higher following passive heating and 34% higher following exercise in the heat, without significant changes in whole-body lipid utilization. In addition, the level of hyperthermia attained during passive pre-heating and exercise in the heat resulted in a 13% decrease in total external work and a significantly higher rate of perceived exertion. CHAPTER 3 summarizes the study results and presents the limitations and applications of the study.