Three experiments were conducted for this dissertation with the goals to; 1) determine conjugated linoleic acid (CLA) effects on net-energy balance (EBAL) and milk production parameters during periods of nutrient/energy stress, and 2) investigate temporal CLA effects on mammary lipogenic gene expression. Study one was designed to determine if abomasal CLA infusion could reduce milk fat synthesis and partition nutrients towards alternative milk components in feed restricted rotationally grazed dairy cows. Data indicate abomasally-infusing CLA reduced milk fat synthesis in nutrient restricted grazing dairy cows and improved calculated EBAL and milk protein production. Another period of transitory stress experienced by the lactating dairy cow is immediately postpartum and study two objectives were to feed rumen inert-CLA to evoke milk fat depression (MFD) and investigate production and bioenergetic parameters. Data indicated a high CLA dose (3 x greater than needed in established lactation) inhibited milk fat synthesis immediately postpartum and improved calculated EBAL in grazing dairy cows. A curvilinear relationship existed between the severity of CLA-induced MFD and milk yield response. Moderate CLA-induced MFD (<~35%) tended to increase milk yield whereas severe MFD (>~35%) diminished this response. Previous research speculated that extensive MFD might decrease Δ⁹-desaturase (stearoyl CoA desaturase; SCD) and subsequent membrane fluidity to such an extent as to adversely affect cellular functions and inhibit milk secretion, thus decreasing milk yield. However, SCD inhibition was temporally independent in the present study, offering little support for the aforementioned theory. Mammary sensitivity to CLA increased as lactation progressed and previous speculations attributed this to reduced contribution of de novo synthesised fatty acids or increased competition from circulating non-esterified fatty acids immediately postpartum. However, data indicate that de novo fatty acids and milk fat trans-10, cis-12 CLA content don’t appreciably change during early lactation, (even though MFD became more severe) offering little support for either hypothesis. Study three investigated the effects of intravenous CLA infusion on temporal expression of mammary lipogenic genes to determine if trans-10, cis-12 CLA down regulates expression of a key gene (i.e. acetyl CoA carboxylase, ACC, the rate limiting enzyme in de novo fatty acid synthesis) and reduction in other mammary lipid synthesis genes is due to lack of substrate (i.e. malonyl CoA), or an alternative indirect mechanism. Data indicated however, that mammary lipogenic genes (ACC, fatty acid synthetase and SCD) followed a similar temporal pattern, providing more support for a global regulator (i.e. sterol regulatory element binding protein-1, peroxisome proliferator-activated receptor-γ or nuclear factor- κB) rather than a specific key enzyme effect.

Conjugated linoleic acid (CLA) is predominantly found in foods of ruminant origin such as milk and processed cheese, and has gained much interest recently due to its beneficial health and biological effects on animals and humans. / The bioconversion of linoleic acid (LA) and linolenic acid (LNA) by a selected Bifidobacterium from healthy infant feces was studied. Bifidobacterium breve JKL03 had the ability to convert linolenic acid (0.2 mg/ml) to CLNA in fermentation of skim milk medium for 24 h up to a yield of 72.0% (up to 74.7% under aerobic conditions) and linoleic acid (0.2 mg/ml) into CLA by fermentation in skim milk medium for 24 h up to a yield of 23.9% (up to 28.0% under aerobic conditions). / B. breve JKL03 was also co-fermented with Lactobacillus acidophilus (NCFMRTM strain), a commonly added starter culture, to observe the resulting effects on growth during fermentation for yogurt production. Fermentation of LNA in skim milk with B. breve JKL03 and L. acidophilus (NCFM) maintained high CLNA production level. On the other hand, CLA production in the same media with both strains did not exhibit as high level as with the single B. breve. / These results are important for the advancement of knowledge on the production of CLA and CLNA in dairy products and for knowledge on the basic metabolic mechanisms for such conversion.

The objectives of this study was to examine the efficacy and safety of graded doses of c9, t11, t10, c12 CLA isomers on body composition, energy expenditure, lipid profile and hepatic biomarkers in hamsters. Male Golden Syrian hamsters (n=105) were randomized to seven treatments (control; 1, 2, 3% of c9, t11; 1, 2, 3% of t10, c12) for 28 days. Compared with control, 1% and 3% t10, c12 had lowered food intake with all three doses of t10, c12 lowering (p<0.0001) body fat mass (g). Groups fed with 1, 2, 3% t10, c12 and 3% c9, t11 treatments showed higher lean mass compared to control and other treatment groups. However, neither body weights, nor serum HDL or triglyceride levels differed across treatment groups. The 3% t10, c12 groups exhibited higher (p<0.0001) cholesterol and LDL-C levels compared to control or other treatment groups. The 2% and 3% t10, c12 groups also presented elevated ALT level (p<0.05). The present data suggest that 3% t10, c12 possess potential adverse effects on liver and posing unfavorable change in lipid profile.

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.

The objectives of this study was to examine the efficacy and safety of graded doses of c9, t11, t10, c12 CLA isomers on body composition, energy expenditure, lipid profile and hepatic biomarkers in hamsters. Male Golden Syrian hamsters (n=105) were randomized to seven treatments (control; 1, 2, 3% of c9, t11; 1, 2, 3% of t10, c12) for 28 days. Compared with control, 1% and 3% t10, c12 had lowered food intake with all three doses of t10, c12 lowering (p<0.0001) body fat mass (g). Groups fed with 1, 2, 3% t10, c12 and 3% c9, t11 treatments showed higher lean mass compared to control and other treatment groups. However, neither body weights, nor serum HDL or triglyceride levels differed across treatment groups. The 3% t10, c12 groups exhibited higher (p<0.0001) cholesterol and LDL-C levels compared to control or other treatment groups. The 2% and 3% t10, c12 groups also presented elevated ALT level (p<0.05). The present data suggest that 3% t10, c12 possess potential adverse effects on liver and posing unfavorable change in lipid profile.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 60-68). Also available on the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xviii, 141 p.; also includes graphics (some col.) Includes bibliographical references (p. 116-130). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 135-166).

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Made available in DSpace on 2014-06-11T19:23:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-11-14Bitstream added on 2014-06-13T20:10:41Z : No. of bitstreams: 1 000739343.pdf: 2203610 bytes, checksum: ac8c342ce3d51256ef5b4bf0a36feb39 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / mortalidade embrionária em bovinos, entre 15 e 19 dias de prenhez, pode ser promovida pela liberação de PGF2 endometrial. A síntese de PGF2 é inibida pela suplementação com compostos ricos em ácido linoléico, como a semente de girassol. Assim, objetivou-se avaliar o efeito e os mecanismos pelos quais a suplementação com semente de girassol atua na performance reprodutiva de fêmeas bovinas de corte. Hipotetizou-se que tal suplementação promove um incremento na taxa de concepção de receptoras de embriões produzidos in vitro submetidas à TETF e que tal efeito decorra de modificações na composição lipídica plasmática e endometrial, alterações na expressão de transcritos envolvidos na biossíntese de eicosanoides e/ou modificações no número e/ou morfometria das glândulas endometriais. No Experimento 1, novilhas mestiças zebuínas submetidas ao protocolo de TETF suplementadas com semente de girassol, por 22 dias a partir da remoção do dispositivo de progesterona, apresentaram maior taxa de concepção em relação ao grupo controle (55,66% vs. 36,94%; P < 0,01). No Experimento 2, vacas Nelore suplementadas com semente de girassol apresentaram maiores concentrações plasmáticas de colesterol total, LDL e HDL; modificações na composição lipídica endometrial e alterações na expressão de transcritos envolvidos na biossíntese de eicosanoides. Conclui-se que a suplementação com semente de girassol aumenta a taxa de concepção por modificar a composição lipídica plasmática e endometrial, a expressão de transcritos envolvidos na biossíntese de eicosanoides e número... ( / Embryonic mortality in cattle, between 15 and 19 days of pregnancy, can be promoted by the release of endometrial PGF2. Synthesis of PGF2 is inhibited by supplementation with compounds rich in linoleic acid such as sunflower seed. This study aimed to evaluate the effects and the mechanisms by which supplementation with sunflower seed acts on reproductive performance of beef cows. It was hypothesized that such supplementation promotes an increase on conception rate of in vitro-produced embryos subjected to FTET; and that this effect arises from changes in plasma lipid composition and endometrial changes in the expression of transcripts involved in the biosynthesis of eicosanoids and/or changes in the number and/or endometrial gland morphology. In Experiment 1, zebu crossbred heifers submitted to the FTET protocol supplemented with sunflower seed, for 22 days from the removal of the progesterone device, showed higher conception rate in the control group (55.66% vs. 36.94% ; P < 0.01). In Experiment 2, Nelore cows supplemented with sunflower seed showed higher plasma concentrations of total cholesterol, LDL and HDL, changes in endometrial lipid composition and changes in the expression of transcripts involved in the biosynthesis of eicosanoids. It was concluded that supplementation with sunflower seeds increases the conception rate by modifying the lipid composition of the plasma and the endometrium, the expression of transcripts involved in the biosynthesis of eicosanoids and number and morphometry of the endometrial glands / FAPESP: 09/09234-9