Changes in long-chain fatty acid composition of milk fat globule membrane and expression of mammary lipogenic genes in dairy cows fed sunflower seeds and rumen-protected choline.

The aim of this experiment was to investigate the effect of dietary supplementation of crushed high oleic sunflower seeds (HOS) and rumen-protected choline (RPC) on the fatty acid (FA) profile of phospholipids and sphingomyelin and mammary transcription of genes that are important for milk fat synthesis and de novo synthesis of sphingolipids. Twenty-four cows were divided into four groups that either received an unsupplemented diet (Control), the Control diet supplemented with 50 g RPC per day, a diet supplemented with HOS at 10% of dry matter, or RPC and HOS in combination (RPC + HOS). RPC supplementation had no effect on the FA composition of milk or sphingomyelin. Cows receiving RPC and RPC + HOS had increased incorporation of C22:5 (n-3) into phospholipids. Milk FA proportion of C18:0 and C18:1 isomers was increased in cows receiving HOS (HOS and RPC + HOS). Sphingomyelin proportion of C22:0 was increased in cows receiving HOS and RPC + HOS, at the expense of C23:0. HOS supplementation further increased the proportion of unsaturated fatty acids (UFA) in milk phospholipids. HOS supplementation increased mammary transcription of UDP-glucose ceramide glycosyltransferase (UGCG), sterol response element-binding protein cleavage-activating protein (SCAP) and peroxisome proliferation-activated receptor Gamma subunit C 1b (PPARGC1b), and reduced transcription of insulin induced gene 1 (INSIG1) and fatty acid-binding protein 3 (FABP3). Dietary supplementation of RPC increased mammary transcription of fatty acid desaturase 1 (FADS1) and longevity assurance gene 2 (LASS2), and reduced transcription of sphingomyelin synthase (SGMS). The results show that the FA profile of milk phospholipids is sensitive to dietary lipid supplementation and, to a minor degree, RPC supplementation. Furthermore, transcription of genes that are important for milk fat synthesis and sphingolipids synthesis is affected by dietary supplementation of RPC and HOS.

Expression, localization, and functional model of cholesterol transporters in lactating and nonlactating mammary tissues of murine, bovine, and human origin.

Members of the ATP-binding cassette (ABC) transporters play a pivotal role in cellular lipid efflux. To identify candidate cholesterol transporters implicated in lipid homeostasis and mammary gland (MG) physiology, we compared expression and localization of ABCA1, ABCG1, and ABCA7 and their regulatory genes in mammary tissues of different species during the pregnancy-lactation cycle. Murine and bovine mammary glands (MGs) were investigated during different functional stages. The abundance of mRNAs was determined by quantitative RT-PCR. Furthermore, transporter proteins were localized in murine, bovine, and human MGs by immunohistochemistry. In the murine MG, ABCA1 mRNA abundance was elevated during nonlactating compared with lactating stages, whereas ABCA7 and ABCA1 mRNA profiles were not altered. In the bovine MG, ABCA1, ABCG1, and ABCA7 mRNAs abundances were increased during nonlactating stages compared with lactation. Furthermore, associations between mRNA levels of transporters and their regulatory genes LXRalpha, PPARgamma, and SREBPs were found. ABCA1, ABCG1, and ABCA7 proteins were localized in glandular MG epithelial cells (MEC) during lactation, whereas during nonlactating stages, depending on species, the proteins showed distinct localization patterns in MEC and adipocytes. Our results demonstrate that ABCA1, ABCG1, and ABCA7 are differentially expressed between lactation and nonlactating stages and in association with regulatory genes. Combined expression and localization data suggest that the selected cholesterol transporters are universal MG transporters involved in transport and storage of cholesterol and in lipid homeostasis of MEC. Because of the species-specific expression patterns of transporters in mammary tissue, mechanisms of cholesterol homeostasis seem to be differentially regulated between species.

Separation of selenium, zinc, and copper compounds in bovine whey using size exclusion chromatography linked to inductively coupled plasma mass spectrometry.

To study the role of trace elements for the quality and nutritional value of bovine milk, the distribution of selenium, zinc, and copper in whey was investigated using a method linking size exclusion chromatography to inductively coupled plasma mass spectrometry (SEC-ICP-MS). Three major peaks were detected for selenium, two peaks for zinc, and five peaks for copper. More than 65% of the selenium was found in protein fractions, mainly in fractions coinciding with the major whey proteins beta-lactoglobulin and alpha-lactalbumin. All zinc was associated with low molecular weight compounds (<5 kDa) and one of these compounds was probably citrate. More than 60% of the copper eluted in protein fractions and two of the five major peaks probably contained metallothionein and citrate. This method was used to compare milk and whey produced by organic and conventional feeding procedures. The selenium content in whey and desalted milk produced using organic regimens was significantly lower than that in conventional samples. Moreover, the proportion of selenium in protein fractions of organic whey was significantly smaller than that in conventional whey, but the distributions of zinc and copper did not differ. This study showed that with the SEC-ICP-MS technique the distribution profiles of several trace elements in whey could be studied in the same run and that the selenium profile differed in whey produced by organic and conventional procedures.

Effects of butter high in ruminant trans and monounsaturated fatty acids on lipoproteins, incorporation of fatty acids into lipid classes, plasma C-reactive protein, oxidative stress, hemostatic variables, and insulin in healthy young men.

BACKGROUND: Evidence suggests that ruminant trans fatty acids (FAs), such as vaccenic acid, do not increase the risk of ischemic heart disease (IHD). However, the effects of ruminant trans FAs on risk markers of IHD have been poorly investigated. OBJECTIVE: The objective was to investigate the effect of butter with a naturally high content of vaccenic acid and a concomitantly higher content of monounsaturated FAs on classic and novel risk markers of IHD. DESIGN: In a double-blind, randomized, 5-wk, parallel intervention study, 42 healthy young men were given 115 g fat/d from test butter that was high in vaccenic acid (3.6 g vaccenic acid/d) or a control butter with a low content of vaccenic acid. Blood and urine samples were collected before and after the intervention. RESULTS: The intake of the vaccenic acid-rich diet resulted in 6% and 9% lower total cholesterol and plasma HDL-cholesterol concentrations, respectively, than did the intake of the control diet (P = 0.05 and 0.002, respectively), whereas the ratio of total to HDL cholesterol did not differ significantly between the groups. The FA composition of lipid classes reflected the FAs' proportion of the test butter. No other differences were observed. CONCLUSIONS: Butter high in ruminant trans and monounsaturated FAs resulted in significantly lower total and HDL cholesterol than did the control butter with higher amounts of saturated FAs. It may be that the differences were due to the greater content of monounsaturated FAs and the lesser content of saturated FAs in the butter rich in ruminant trans FAs, rather than to the content of vaccenic acid per se.

Whey protein reduces early life weight gain in mice fed a high-fat diet.

An increasing number of studies indicate that dairy products, including whey protein, alleviate several disorders of the metabolic syndrome. Here, we investigated the effects of whey protein isolate (whey) in mice fed a high-fat diet hypothesising that the metabolic effects of whey would be associated with changes in the gut microbiota composition. Five-week-old male C57BL/6 mice were fed a high-fat diet ad libitum for 14 weeks with the protein source being either whey or casein. Faeces were collected at week 0, 7, and 13 and the fecal microbiota was analysed by denaturing gradient gel electrophoresis analyses of PCR-derived 16S rRNA gene (V3-region) amplicons. At the end of the study, plasma samples were collected and assayed for glucose, insulin and lipids. Whey significantly reduced body weight gain during the first four weeks of the study compared with casein (P<0.001-0.05). Hereafter weight gain was similar resulting in a 15% lower final body weight in the whey group relative to casein (34.0±1.0 g vs. 40.2±1.3 g, P<0.001). Food intake was unaffected by protein source throughout the study period. Fasting insulin was lower in the whey group (P<0.01) and glucose clearance was improved after an oral glucose challenge (P<0.05). Plasma cholesterol was lowered by whey compared to casein (P<0.001). The composition of the fecal microbiota differed between high- and low-fat groups at 13 weeks (P<0.05) whereas no difference was seen between whey and casein. In conclusion, whey initially reduced weight gain in young C57BL/6 mice fed a high-fat diet compared to casein. Although the effect on weight gain ceased, whey alleviated glucose intolerance, improved insulin sensitivity and reduced plasma cholesterol. These findings could not be explained by changes in food intake or gut microbiota composition. Further studies are needed to clarify the mechanisms behind the metabolic effects of whey.

Alpha-tocopherol counteracts the cytotoxicity induced by ochratoxin a in primary porcine fibroblasts.

The aims of the current study were to determine the half-lethal concentration of ochratoxin A (OTA) as well as the levels of lactate dehydrogenase release and DNA fragmentation induced by OTA in primary porcine fibroblasts, and to examine the role of α-tocopherol in counteracting its toxicity. Cells showed a dose-, time- and origin-dependent (ear vs. embryo) sensitivity to ochratoxin A. Pre-incubation for 3 h with 1 nM α-tocopherol significantly (P < 0.01) reduced OTA cytotoxicity, lactate dehydrogenase release and DNA damage in both fibroblast cultures. These findings indicate that α-tocopherol supplementation may counteract short-term OTA toxicity, supporting its defensive role in the cell membrane.

Diets rich in conjugated linoleic acid and vaccenic acid have no effect on blood pressure and isobaric arterial elasticity in healthy young men.

The objective of this study was to examine the effect on blood pressure (BP) and isobaric arterial elasticity (AE), as a measure of arterial health, of a commercial mixture of conjugated linoleic acids (CLA) and of milk fat produced through livestock feeding to have a high content of vaccenic acid (VA). Healthy young men (n = 60) with a BMI of 22.5 +/- 2 kg/m2 (mean +/- SD) participated in this double-blind, randomized, 5-wk, parallel intervention study. The participants substituted 115 g of their daily fat intake with fat from 1 of 3 test diets: 1) CLA-diet rich in CLA (4.7 g/d of c9,t11- and t10,c12-CLA isomers in equal amounts); 2) VA-diet rich in VA (3.6 g/d); or 3) C-diet, a control diet with a low content of VA and CLA. All test diets were based on milk fat. BP and AE (measured by an oscillometric method) were measured before and after the intervention period. The effects of the test diets did not differ on any outcome variable: e.g., systolic- and diastolic blood pressure (SBP and DBP), pulse pressure (PP), isobaric arterial compliance (AC), distensibility (AD), or volume (AV). In conclusion, diets rich in milk fat and either CLA or VA have no effect on BP or AE indices in healthy young men compared with a control diet.