Doctor of Philosophy / Department of Animal Sciences and Industry / Terry Houser / One experiment was conducted to determine the collagen and adipocyte characteristics in pork belly fat with different iodine values (IV) and if these factors contribute to belly firmness. An additional two experiments were conducted to create an objective method to score bacon distortion during cooking and to determine how IV and cooking method contribute to bacon distortion. Experiment 1 sorted pork bellies (n=72) into three IV categories: High 76.5 g/100g, Intermediate 70.5 g/100g, and Low 64.9 g/100g. Belly characteristics and firmness were measured before processing into bacon. After processing, 3 bacon slices were selected from the belly and analyzed for histochemistry and collagen analysis. No differences were observed between belly characteristics, while High IV bellies showed softer bellies. Adipocyte characteristics remained unchanged between IV groups. High IV bellies showed greater amounts of collagen. Experiment 2 cooked bacon slices (n=585) on three different appliances (griddle, microwave, and oven) and scored the resulting distortion using a subjective scale. Raw and cooked bacon characteristics were measured to determine which response variables contributing to distortion. Bacon slices were removed from 6 different locations within each belly sampled. Two distortion measurements were created to objectively describe distortion response (crest frequency and bacon distortion index. Subjective distortion scores, crest frequency, bacon distortion index, and raw and cooked bacon characteristics were shown to change between locations of the belly. Accuracy of predictive equations developed to predict distortion scores were low. Experiment 3 evaluated how IV interacts with cooking methodology to influence cooking characteristics, fat quality and distortion of bacon. Bacon slices (n=300) were organized into two IV categories, Low (61.52 to 65.54 g/100g) and High (78.83 to 85.34 g/100g) and cooked using three different appliances (oven, microwave, and griddle). Bacon from the Low IV group had the greatest amount of fat. Cooking bacon on a griddle showed the greatest distortion scores, while the oven produced bacon with the lowest distortion scores. Bacon with higher IV produced bacon with increased distortion scores. Bacon from the High IV group showed smaller cooked dimensions than the Low IV bacon. Neither cooking method nor IV level affected the cooked fatty acid composition.

Master of Science / Department of Animal Sciences and Industry / Jim L. Nelssen / Five-hundred and four barrows and gilts were used in four experiments to determine the influence of dietary ingredients on fat quality. Experiment 1 evaluated feeding duration of choice white grease (CWG) and soybean oil. Increasing feeding duration of pigs fed CWG or soybean oil increased (quadratic, P < 0.01) iodine value (IV) in jowl fat and backfat. Pigs fed soybean oil had increased (P < 0.01) IV in jowl and backfat compared with pigs fed CWG. In Exp. 2 dried distillers grains with solubles (DDGS), extruded expelled soybean meal (EESM), and CWG were used to evaluate diets with common iodine value product (IVP) from ingredients varying in unsaturated fat level and concentration. Pigs fed either diet with DDGS had increased (P = 0.02) backfat and jowl fat IV, compared with all other treatments. Pigs fed EESM had increased (P = 0.04) backfat and jowl fat IV compared with the control, low CWG, and high CWG. Pigs fed low CWG and high CWG had increased (P = 0.04) jowl fat IV compared to the control. Increasing dietary fat increased carcass fat IV, with unsaturated fats from DDGS and EESM having a greater affect than more saturated fats, such as CWG, even when formulated to the same IVP. Experiment 3 evaluated the effects of increasing CWG in corn- and sorghum-based diets on fat quality. There was a grain source X fat level interaction (P = 0.04) for IV in both backfat and jowl fat. Adding CWG increased IV in backfat and jowl fat for pigs fed corn- and sorghum-based diets; however, the greatest increase was between 0 and 2.5% CWG in sorghum-based diets and between 2.5 and 5% CWG in corn-based diets. Despite this interaction, pigs fed corn-based diets had increased (P < 0.01) backfat and jowl fat IV compared with pigs fed sorghum-based diets. Increasing CWG increased (linear, P < 0.01) IV in backfat and jowl fat. Experiment 4 examined the effects of DDGS on fat quality. Backfat, jowl fat, and belly fat IV increased (linear, P = 0.02) with increasing DDGS in both the pigs marketed on d 57 and 78.

Doctor of Philosophy / Department of Animal Sciences and Industry / Jim L. Nelssen / Eleven-thousand one-hundred eighty-five pigs were used in 11 experiments to determine effects of birth-weight, feeder design, and dietary astaxanthin (AX) and ractopamine HCl (RAC) on growth, carcass, and pork quality characteristics of pigs. Also, data from 27 experiments were used in meta-analyses to improve prediction of pork fat iodine value (IV). In Exp. 1, increased birth-weight resulted in greater (quadratic, P < 0.05) pre-weaning survivability, ADG, final BW, and likelihood of achieving full-value market at 181-d of age. In Exp. 2, 3, 4, 6, 7, and 8, pigs using the wet-dry feeder (WD) had greater (P < 0.05) ADG, ADFI, and final BW than those using the conventional dry feeder (CD). Pigs using WD had poorer (P < 0.05) G:F in Exp. 3 and 4, and increased (P < 0.05) HCW and backfat depth in Exp. 3, 4, 6, and 7, compared to pigs fed using CD. In Exp. 5, pigs using WD from 19 to 38 kg had decreased (P < 0.02) ADFI and better G:F than pigs using CD. Increased feeder opening of WD increased (P < 0.05) ADG, ADFI, and final BW in Exp. 5, 6, and 7; as well as HCW and backfat depth in Exp. 6 and 7. Reducing WD opening at 28- and 56-d in Exp. 7 decreased (P < 0.05) ADG, ADFI, and backfat depth. Different openings of CD had little effect on performance in Exp. 5 and 6. In Exp. 8, changing water-source of WD to a separate location during late-finishing reduced (P < 0.05) overall ADG, ADFI, and final BW. Limited responses to AX were observed in Exp. 9, 10, and 11, but ADG, G:F, final BW, HCW, and fat-free lean were improved (P < 0.05) for pigs fed RAC in Exp. 10 and 11. Total color change during retail display of LM chops for gilts and pigs fed RAC was reduced (P < 0.05) in Exp. 10 and 11, indicating their color shelf-life improved. In the meta-analyses, models using dietary PUFA with ADG, BW, or backfat depth improved the fat IV prediction from R2 = 0.45 to R2 = 0.90.

Master of Science / Department of Animal Sciences and Industry / Terry A. Houser / Two experiments were conducted to determine the effects of dried distillers grains with solubles (DDGS) on pork loin and fat quality. In the first experiment, 1,160 barrows (PIC) were used in a 70-d study to determine the influence of DDGS and glycerol on pork loin and fat quality attributes. Barrows were fed a corn-soybean meal based diet with the addition of selected levels of DDGS (0 or 20%) and glycerol (0, 2.5, or 5%) feed stuffs. Loins from the two heaviest pigs in each pen were removed for evaluation of pork loin and fat quality. Experiment two was a pilot study, in which eight non-pregnant sows were fed either 0 or 50% DDGS with a corn soybean meal based diet for 92-d. In the first experiment, there were no DDGS x glycerol interactions for purge loss %, instrumental color (L*a*b*), visual color, marbling score, drip loss %, visual color, pH, Warner-Bratzler shear force (WBSF), cook loss %, myofibrillar tenderness, juiciness, pork flavor intensity, connective tissue amount, and overall tenderness. There was a DDGS x glycerol interaction (P<0.03) for off-flavor intensity. Pigs fed diets with 20% DDGS had higher WBSF values, lower myofibrillar tenderness, lower overall tenderness scores, lower connective tissue scores, and had more off-flavors (P<0.05). Loin fatty acid analysis revealed an increase in palmitoleic, linoleic, and eicosadienoic acids (P<0.05) and iodine value (P<0.03) for pigs fed 20% DDGS. In the second experiment, there were no differences (P>0.64) in BW or backfat change for sows fed either 0 or 50% DDGS. No differences (P>0.23) in lipid oxidation from lean trimmings as measured by 2-thiobarbituric acid reactive substances (TBARS) assay were reported either initially or after 5 d of retail display for sows fed either 0 or 50% DDGS. As expected, lipid oxidation increased (P<0.003) as measured by TBARS assay for both treatments from d 1 to 5. Jowl fatty acid analysis revealed an increase in linoleic acid (P<0.01), total polyunsaturated fatty acids (P<0.01), and the ratio of polyunsaturated fatty acids to saturated fatty acids (P<0.03) for sows fed 50% DDGS.

Os ácidos graxos e índices de qualidade da gordura da dieta tem papel importante na homeostase glicêmica, mas estudos sobre o consumo alimentar desses nutrientes e sua associação com o diabetes mellitus gestacional (DMG) são escassos. O objetivo do presente estudo consistiu na investigação da relação entre o diabetes gestacional e a ingestão usual de ácidos graxos específicos e de índices de qualidade da gordura da dieta de mulheres no segundo trimestre gestacional. Estudo transversal conduzido entre 799 gestantes adultas de Ribeirão Preto-SP-Brasil. Para a estimativa da dieta usual o Multiple Source Method foi utilizado, empregando-se dois IR24h obtidos a partir da 24a semana gestacional. As gestantes foram entrevistadas enquanto realizavam teste oral de tolerância à glicose e os critérios da International Association of Diabetes and Pregnancy Study Groups foram empregados para o diagnóstico do DMG. A associação entre os tercis de ácidos graxos da dieta durante a gestação e o DMG foi avaliada por análises de regressão logística, ajustadas por idade, escolaridade, paridade, semana gestacional, IMC pré-gestacional e atual, DMG prévia, histórico familiar de diabetes, tabagismo, prática de atividade física, fibra dietética, energia e ácidos graxos. A média (DP) de idade das gestantes avaliadas foi de 28 (5) anos e 18,9% apresentaram DMG. Verificou-se associação inversa entre o maior tercil de ingestão de ácidos graxos ômega 3 totais [0,21(0,08-0,56)] e ácido graxo linolênico [0,28(0,11-0,71)] e o DMG, após ajuste múltiplo. Observou-se associação direta entre o terceiro tercil do índice de trombogenicidade da dieta [2,55(1,30-5,02)] e associação inversa entre o maior tercil da razão HH [0,43(0,23-0,80)] e o DMG, quando comparados ao menor tercil, após ajuste múltiplo. A qualidade da gordura da dieta durante a gestação é fortemente associada com o diabetes mellitus gestacional. / Fatty acids and indices of dietary fat quality plays an important role in glucose homeostasis, but studies on the dietary intake of these nutrients and its association with gestational diabetes mellitus (GDM) are scarce. The aim of the present study was to investigate the relationship between GDM and the usual intake of specific fatty acids and indices of dietary fat quality in women in the second trimester of pregnancy. This was a cross-sectional study conducted with 799 adult pregnant women in Ribeirão Preto (Sao Paulo), Brazil. We used the Multiple Source Method to estimate participants usual diet, employing two IR24hs obtained from the 24th week of gestation. The women were interviewed when they came in for their oral glucose tolerance test and GDM was diagnosed using the International Association of Diabetes and Pregnancy Study Groups criteria. We used logistic regression analysis to assess the correlation between GDM and dietary fatty acid tertiles during pregnancy, adjusted for age, education, parity, gestational week, pre-pregnancy and current BMI, prior GDM, family history of diabetes, smoking, physical activity, dietary fiber, energy and fatty acids. The mean (SD) age of the pregnant women was 28 (5) years and 18.9% had GDM. There was an inverse correlation between the highest tertile of total omega 3 intake [0.21 (0.08-0.56)] and linolenic fatty acid intake [0.28 (0.11-0.71)] and GDM, after multiple adjustments. We observed a positive correlation between GDM and the highest tertile of the dietary index of thrombogenicity [2.55 (1.30-5.02)] and a negative correlation between GDM and the highest tertile of the hypocholesterolaemic/hypercholesterolaemic fatty acids ratio [0.43 (0.23-0.80)], after multiple adjustments. The quality of dietary fat during pregnancy is strongly associated with gestational diabetes mellitus.

Os ácidos graxos e índices de qualidade da gordura da dieta tem papel importante na homeostase glicêmica, mas estudos sobre o consumo alimentar desses nutrientes e sua associação com o diabetes mellitus gestacional (DMG) são escassos. O objetivo do presente estudo consistiu na investigação da relação entre o diabetes gestacional e a ingestão usual de ácidos graxos específicos e de índices de qualidade da gordura da dieta de mulheres no segundo trimestre gestacional. Estudo transversal conduzido entre 799 gestantes adultas de Ribeirão Preto-SP-Brasil. Para a estimativa da dieta usual o Multiple Source Method foi utilizado, empregando-se dois IR24h obtidos a partir da 24a semana gestacional. As gestantes foram entrevistadas enquanto realizavam teste oral de tolerância à glicose e os critérios da International Association of Diabetes and Pregnancy Study Groups foram empregados para o diagnóstico do DMG. A associação entre os tercis de ácidos graxos da dieta durante a gestação e o DMG foi avaliada por análises de regressão logística, ajustadas por idade, escolaridade, paridade, semana gestacional, IMC pré-gestacional e atual, DMG prévia, histórico familiar de diabetes, tabagismo, prática de atividade física, fibra dietética, energia e ácidos graxos. A média (DP) de idade das gestantes avaliadas foi de 28 (5) anos e 18,9% apresentaram DMG. Verificou-se associação inversa entre o maior tercil de ingestão de ácidos graxos ômega 3 totais [0,21(0,08-0,56)] e ácido graxo linolênico [0,28(0,11-0,71)] e o DMG, após ajuste múltiplo. Observou-se associação direta entre o terceiro tercil do índice de trombogenicidade da dieta [2,55(1,30-5,02)] e associação inversa entre o maior tercil da razão HH [0,43(0,23-0,80)] e o DMG, quando comparados ao menor tercil, após ajuste múltiplo. A qualidade da gordura da dieta durante a gestação é fortemente associada com o diabetes mellitus gestacional. / Fatty acids and indices of dietary fat quality plays an important role in glucose homeostasis, but studies on the dietary intake of these nutrients and its association with gestational diabetes mellitus (GDM) are scarce. The aim of the present study was to investigate the relationship between GDM and the usual intake of specific fatty acids and indices of dietary fat quality in women in the second trimester of pregnancy. This was a cross-sectional study conducted with 799 adult pregnant women in Ribeirão Preto (Sao Paulo), Brazil. We used the Multiple Source Method to estimate participants usual diet, employing two IR24hs obtained from the 24th week of gestation. The women were interviewed when they came in for their oral glucose tolerance test and GDM was diagnosed using the International Association of Diabetes and Pregnancy Study Groups criteria. We used logistic regression analysis to assess the correlation between GDM and dietary fatty acid tertiles during pregnancy, adjusted for age, education, parity, gestational week, pre-pregnancy and current BMI, prior GDM, family history of diabetes, smoking, physical activity, dietary fiber, energy and fatty acids. The mean (SD) age of the pregnant women was 28 (5) years and 18.9% had GDM. There was an inverse correlation between the highest tertile of total omega 3 intake [0.21 (0.08-0.56)] and linolenic fatty acid intake [0.28 (0.11-0.71)] and GDM, after multiple adjustments. We observed a positive correlation between GDM and the highest tertile of the dietary index of thrombogenicity [2.55 (1.30-5.02)] and a negative correlation between GDM and the highest tertile of the hypocholesterolaemic/hypercholesterolaemic fatty acids ratio [0.43 (0.23-0.80)], after multiple adjustments. The quality of dietary fat during pregnancy is strongly associated with gestational diabetes mellitus.

<p>Lipid peroxidation is thought to be an important factor in the pathophysiology of a number of diseases and in the process of ageing, but its measurement <i>in vivo</i> has been difficult. The aim of this thesis was to evaluate methods for measurement of lipid peroxidation <i>in vivo</i> that are suitable for clinical investigations, and to apply these methods in animal and human studies investigating basal conditions and situations associated with increased lipid peroxidation.</p><p>The ferrous oxidation in xylenol orange assay for quantification of total plasma lipid hydroperoxides was re-evaluated regarding sample handling and storage. It was shown to be a useful tool for analyses of fresh but not stored plasma samples.</p><p>A methodology for measurement of the total amount (sum of free and esterified) of an F₂-isoprostane, 8-iso-prostaglandin F_2α, in tissues using alkaline hydrolysis in combination with an existing radioimmunoassay was developed. High levels of 8-iso-prostaglandin F_2α in rat liver tissue were quantified by this technique both at basal conditions and in an experimental model of increased lipid peroxidation induced by carbon tetrachloride.</p><p>Supplementation with vitamin E to rats decreased both non-enzymatic and enzymatic lipid peroxidation as measured by 8-iso-prostaglandin F_2α and a major prostaglandin F_2α metabolite. This was verified both in the urine at basal conditions, and in the urine and liver tissue after carbon tetrachloride induced lipid peroxidation.</p><p>In a randomised cross-over study in humans, a rapeseed oil-based diet with an increased proportion of easily oxidised polyunsaturated fatty acids was compared to a control diet rich in saturated fats. The rapeseed oil-based diet did not seem to increase the degree of lipid peroxidation in plasma and urine as measured by 8-iso-prostaglandin F_2α, hydroperoxides and malondialdehyde, presumably due to a sufficient content of antioxidants in the rapeseed oil diet.</p><p>In conclusion, the simultaneous measurement of several biomarkers of lipid peroxidation is a promising approach for future studies investigating the possible role of lipid peroxidation <i>in vivo</i> under basal conditions and in the pathology of diseases.</p>

<p>Insulin sensitivity is related to the fatty acid profile of skeletal muscle. The aim of this thesis was to investigate whether physical activity and dietary fat quality, independent of each other, influence the fatty acid composition of the skeletal muscle lipids. In an intervention study where middle-aged men were exercising for six weeks, and in a cross-sectional study comparing sedentary with endurance trained young men, it was demonstrated that the fatty acid composition of skeletal muscle lipids differed between physical active and inactive men. In brief, a lower proportion of palmitic acid (16:0) and total n-6 polyunsaturated fatty acids (PUFA) and a higher proportion of stearic (18:0) and oleic acid (18:1n-9) and total n-3 PUFA in the muscle phospholipids were associated with physical activity, despite similar fatty acid composition of the diet. In the second study, that included a larger training volume, differences in the fatty acid profile were also found in the skeletal muscle triglycerides. </p><p>In contrast, after short-term supra-maximal exercise we found no significant changes in the proportion of the fatty acids in skeletal muscle. </p><p>Furthermore, after a treatment period of three months, with diets with various dietary fat quality, the proportions of saturated fatty acids (14:0, 15:0 and 17:0) were higher and the proportion of 18:1 n-9 lower in subjects with a high intake of saturated fatty acids compared with subjects with a high intake of monounsaturated fatty acids. In addition subjects given n-3 supplementation had a higher proportion of total n-3 PUFA and lower n-6 PUFA in the skeletal muscle phospholipids than controls. Differences similar to those observed in the phospholipids were found in the triglycerides. </p><p>In summary, these results suggest that regular aerobic physical activity and dietary fat quality influence the fatty acid composition of the skeletal muscle lipids, which may affect insulin sensitivity and glucose homeostasis. </p>

Lipid peroxidation is thought to be an important factor in the pathophysiology of a number of diseases and in the process of ageing, but its measurement in vivo has been difficult. The aim of this thesis was to evaluate methods for measurement of lipid peroxidation in vivo that are suitable for clinical investigations, and to apply these methods in animal and human studies investigating basal conditions and situations associated with increased lipid peroxidation. The ferrous oxidation in xylenol orange assay for quantification of total plasma lipid hydroperoxides was re-evaluated regarding sample handling and storage. It was shown to be a useful tool for analyses of fresh but not stored plasma samples. A methodology for measurement of the total amount (sum of free and esterified) of an F2-isoprostane, 8-iso-prostaglandin F2α, in tissues using alkaline hydrolysis in combination with an existing radioimmunoassay was developed. High levels of 8-iso-prostaglandin F2α in rat liver tissue were quantified by this technique both at basal conditions and in an experimental model of increased lipid peroxidation induced by carbon tetrachloride. Supplementation with vitamin E to rats decreased both non-enzymatic and enzymatic lipid peroxidation as measured by 8-iso-prostaglandin F2α and a major prostaglandin F2α metabolite. This was verified both in the urine at basal conditions, and in the urine and liver tissue after carbon tetrachloride induced lipid peroxidation. In a randomised cross-over study in humans, a rapeseed oil-based diet with an increased proportion of easily oxidised polyunsaturated fatty acids was compared to a control diet rich in saturated fats. The rapeseed oil-based diet did not seem to increase the degree of lipid peroxidation in plasma and urine as measured by 8-iso-prostaglandin F2α, hydroperoxides and malondialdehyde, presumably due to a sufficient content of antioxidants in the rapeseed oil diet. In conclusion, the simultaneous measurement of several biomarkers of lipid peroxidation is a promising approach for future studies investigating the possible role of lipid peroxidation in vivo under basal conditions and in the pathology of diseases.

Insulin sensitivity is related to the fatty acid profile of skeletal muscle. The aim of this thesis was to investigate whether physical activity and dietary fat quality, independent of each other, influence the fatty acid composition of the skeletal muscle lipids. In an intervention study where middle-aged men were exercising for six weeks, and in a cross-sectional study comparing sedentary with endurance trained young men, it was demonstrated that the fatty acid composition of skeletal muscle lipids differed between physical active and inactive men. In brief, a lower proportion of palmitic acid (16:0) and total n-6 polyunsaturated fatty acids (PUFA) and a higher proportion of stearic (18:0) and oleic acid (18:1n-9) and total n-3 PUFA in the muscle phospholipids were associated with physical activity, despite similar fatty acid composition of the diet. In the second study, that included a larger training volume, differences in the fatty acid profile were also found in the skeletal muscle triglycerides. In contrast, after short-term supra-maximal exercise we found no significant changes in the proportion of the fatty acids in skeletal muscle. Furthermore, after a treatment period of three months, with diets with various dietary fat quality, the proportions of saturated fatty acids (14:0, 15:0 and 17:0) were higher and the proportion of 18:1 n-9 lower in subjects with a high intake of saturated fatty acids compared with subjects with a high intake of monounsaturated fatty acids. In addition subjects given n-3 supplementation had a higher proportion of total n-3 PUFA and lower n-6 PUFA in the skeletal muscle phospholipids than controls. Differences similar to those observed in the phospholipids were found in the triglycerides. In summary, these results suggest that regular aerobic physical activity and dietary fat quality influence the fatty acid composition of the skeletal muscle lipids, which may affect insulin sensitivity and glucose homeostasis.