Contrasting cellularity and fatty acid composition in fat depots from Alentejana and Barrosã bovine breeds fed high and low forage diets

During the finishing phase of bovines, large amounts of subcutaneous and visceral fats are deposited leading to production inefficiencies with major impact on meat quality. A better understanding of the cellularity features of the main fat depots could provide strategies for adipose tissue manipulation. This study assessed the effect of feeding diets with distinct forage to concentrate ratios on the cellularity of two fat depots of beef cattle and their implications on the fatty acid profile. Thus, two phylogenetically distant Portuguese bovine breeds, Alentejana and Barrosã, were selected. The results did not show differences in subcutaneous fat deposition nor in visceral fat depots partitioning. Plasma adipokines concentration failed to show a consistent relationship with fatness, as leptin remained constant in all experimental groups, whereas interleukin-6 was influenced by breed. Fat depot seems to determine the area and number of adipocytes, with larger adipocytes and a lower number of cells in subcutaneous fat than in mesenteric fat. Neither breed nor diet influenced adipocytes area and number. The contents of total fatty acids, partial sums of fatty acids and conjugated linoleic acid isomeric profile were affected by breed and fat depot. The incorporation of saturated fatty acids (SFA), trans fatty acids, polyunsaturated fatty acids (PUFA) and branched chain fatty acids (BCFA) was higher in mesenteric fat depot, whereas subcutaneous fat depot had greater percentages of monounsaturated fatty acids (MUFA). In addition, SFA and MUFA proportions seem to be breed-related. In spite of the less relevant role of diet, the percentages of PUFA and BCFA were influenced by this factor. Under these experimental conditions, the effect of fat depot on cellularity and fatty acid composition prevails over breed or diet, as reinforced by the principal component analysis.     

The effect of unsaturated and saturated dietary lipids on the pattern of daily torpor and the fatty acid composition of tissues and membranes of the deer mouse Peromyscus maniculatus

Summary Dieary lipids strongly influence the pattern of torpor and the body lipid composition of mammalian hibernators. The object of the present study was to investigate whether these diet-induced physiological and biochemical changes also occur in species that show shallow, daily torpor. Deer mice, Peromyscus maniculatus, were fed with rodent chow (control diet) or rodent chow with either 10% sunflower seed oil (unsaturated diet) or 10% sheep fat (saturated diet). Animals on the unsaturated diet showed a greater occurrence of torpor (80–100% vs 26–43%), longer torpor bouts (4.5 vs 2.25 h), a lower metabolic rate during torpor (0.96 vs 2.25 ml O₂·g^-1·h^-1), and a smaller loss of body mass during withdrawal of food (2.35 vs 3.90 g) than animals on the saturated diet; controls were intermediate. These diet-induced physiological changes were associated with significant alterations in the fatty acid composition of depot fat, leg muscle and brain total lipids, and heart mitochondrial phospholipids. Significant differences in the total unsaturated fatty acid (UFA) content between animals on saturated and unsaturated diet were observed in depot fat (55.7% vs 81.1%) and leg muscle (56.4% vs 72.1%). Major compositional differences between diet groups also occurred in the concentration of n6 and/or n3 fatty acids of brain and heart mitochondria. The study suggests that dietary lipids may play an important role in the seasonal adjustment of physiology in heterothermic mammals.Abbreviations EDTA ethylenediaminetetra-acetic acid - HEPES N-2 hydroxyethylpiperazine-N¹-2-ethanesulphonic acid - MUFA monounsaturated fatty acids - PUFA polyunsaturated fatty acids - RMR Testing metabolic rate - SD standard deviation - SFA saturated fatty acids - SNK Student-Newman-Keuls test - T₁ air temperature - T_b body temperature - UFA unsaturated fatty acids - rate of oxygen consumption Dedicated to the late John K. Raison     

Dietary fats,selected body temperature and tissue fatty acid composition of agamid lizards (Amphibolurus nuchalis)

The composition of tissue and membrane fatty acids in ectothermic vertebrates is influenced by both temperature acclimation and diets. If such change in body lipid composition and thermal physiology were linked, a diet-induced change in body lipid composition should result in a change in thermal physiology. We therefore investigated whether the selected body temperature of the agamid lizardAmphibolurus nuchalis (body mass 20 g) is influenced by the lipid composition of dietary fatty acids and whether diet-induced changes in thermal physiology are correlated with changes in body lipid composition. The selected body temperature in two groups of lizards was indistinguishable before dietary treatments. The selected body temperature in lizards after 3 weeks on a diet rich in saturated fatty acids rose by 2.1 °C (photophase) and 3.3 °C (scotophase), whereas the body temperature of lizards on a diet rich in unsaturated fatty acids fell by 1.5 °C (photophase) and 2.0 °C (scotophase). Significant diet-induced differences were observed in the fatty acid composition of depot fat, liver and muscle. These observations suggest that dietary lipids may influence selection of body temperature in ectotherms via alterations of body lipid composition.Abbreviations bm body mass - FA fatty acid(s) - MUFA monounsaturated fatty acids - PUFA polyunsaturated fatty acids - SFA saturated fatty acids - T _a air temperature - T _b body temperature - UFA unsaturated fatty acids     

Fatty acid composition of the depot fats of the Polynesian rat,Rattus exulans,Tokelau Islands

The fatty acid composition of the stomach contents, adipose tissue, and perinephric fat of Polynesian rats (Rattus exulans Peale), from the Tokelau Is indicated that the dietary fat consisted mainly, if not exclusively, of coconut oil. Lower ratios of lauric : myristic acids were found in the depot fats of the Polynesian rats than in the dietary coconut oil. These results were consistent with chain elongation of lauric to myristic acid after ingestion, as previously reported in rats and other mammals.     

The degree of dietary fatty acid unsaturation affects torpor patterns and lipid composition of a hibernator

Diets rich in unsaturated and polyunsaturated fatty acids have a positive effect on mammalian torpor, whereas diets rich in saturated fatty acids have a negative effect. To determine whether the number of double bonds in dietary fatty acids are responsible for these alterations in torpor patterns, we investigated the effect of adding to the normal diet 5% pure fatty acids of identical chain length (C18) but a different number of double bonds (0, 1, or 2) on the pattern of hibernation of the yellow-pine chipmunk, Eutamias amoenus. The response of torpor bouts to a lowering of air temperature and the mean duration of torpor bouts at an air temperature of 0.5°C (stearic acid C18:0, 4.5±0.8 days, oleic acid C18:1, 8.6±0.5 days; linoleic acid C18:2, 8.5±0.7 days) differed among animals that were maintained on the three experimental diets. The mean minimum body temperatures (C18:0, +2.3±0.3°C; C18:1, +0.3±0.2°C; C18:2,-0.2±0.2°C), which torpid individuals defended by an increase in metabolic rate, and the metabolic rate of torpid animals also differed among diet groups. Moreover, diet-induced differences were observed in the composition of total lipid fatty acids from depot fat and the phospholipid fatty acids of cardiac mitochondria. For depot fat 7 of 13 and for heart mitochondria 7 of 14 of the identified fatty acids differed significantly among the three diet groups. Significant differences among diet groups were also observed for the sum of saturated, unsaturated and polyunsaturated fatty acids. These diet-induced alterations of body fatty acids were correlated with some of the diet-induced differences in variables of torpor. The results suggest that the degree of unsaturation of dietary fatty acids influences the composition of tissues and membranes which in turn may influence torpor patterns and thus survival of hibernation.Abbreviations bm body mass - T _a air temperature - T _b body temperature - FA fatty acid - MR metabolic rate - MUFA monounsaturated fatty acids - PUFA polyunsaturated fatty acids - VO₂ rate of oxygen consumption - SFA saturated fatty acids - UFA unsaturated fatty acids - UI unsaturation index - SNK Student-Newman-Keuls test     

The microbiome affects liver sphingolipids and plasma fatty acids in a murine model of the Western diet based on soybean oil

Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the United States America are enriched in soybean oil, composed of unsaturated fatty acids, either linoleic or oleic acid. Here, we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high or low in high-linoleic-acid soybean oil as the sole source of fat. Conventional and germfree mice gained relative fat weight and all mice consumed more calories on the high fat vs. low fat soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso-C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet and that microbial colonization influences liver sphingolipid pools regardless of diet.     

The role of lipid components of the diet in the regulation of the fatty acid composition of the rat liver endoplasmic reticulum and lipid peroxidation

The fatty acid compositions of the lipids and the lipid peroxide concentrations and rates of lipid peroxidation were determined in suspensions of liver endoplasmic reticulum isolated from rats fed on synthetic diets in which the fatty acid composition had been varied but the remaining constituents (protein, carbohydrate, vitamins and minerals) kept constant. Stock diet and synthetic diets containing no fat, 10% corn oil, herring oil, coconut oil or lard were used. The fatty acid composition of the liver endoplasmic reticulum lipid was markedly dependent on the fatty acid composition of the dietary lipid. Feeding a herring-oil diet caused incorporation of 8.7% eicosapentaenoic acid (C_20:5) and 17% docosahexaenoic acid (C_22:6), but only 5.1% linoleic acid (C_18:2) and 6.4% arachidonic acid (C_20:4), feeding a corn-oil diet caused incorporation of 25.1% C_18:2, 17.8% C_20:4 and 2.5% C_22:6 fatty acids, and feeding a lard diet caused incorporation of 10.3% C_18:2, 13.5% C_20:4 and 4.3% C_22:6 fatty acids into the liver endoplasmic-reticulum lipids. Phenobarbitone injection (100mg/kg) decreased the incorporation of C_20:4 and C_22:6 fatty acids into the liver endoplasmic reticulum of rats fed on a lard, corn-oil or herring-oil diet. Microsomal lipid peroxide concentrations and rates of peroxidation in the presence of ascorbate depended on the nature and quantity of the polyunsaturated fatty acids in the diet. The lipid peroxide content was 1.82±0.30nmol of malonaldehyde/mg of protein and the rate of peroxidation was 0.60±0.08nmol of malonaldehyde/min per mg of protein after feeding a fat-free diet, and the values were increased to 20.80nmol of malonaldehyde/mg of protein and 3.73nmol of malonaldehyde/min per mg of protein after feeding a 10% herring-oil diet in which polyunsaturated fatty acids formed 24% of the total fatty acids. Addition of α-tocopherol to the diets (120mg/kg of diet) caused a very large decrease in the lipid peroxide concentration and rate of lipid peroxidation in the endoplasmic reticulum, but addition of the synthetic anti-oxidant 2,6-di-t-butyl-4-methylphenol to the diet (100mg/kg of diet) was ineffective. Treatment of the animals with phenobarbitone (1mg/ml of drinking water) caused a sharp fall in the rate of lipid peroxidation. It is concluded that the polyunsaturated fatty acid composition of the diet regulates the fatty acid composition of the liver endoplasmic reticulum, and this in turn is an important factor controlling the rate and extent of lipid peroxidation in vitro and possibly in vivo.     

Improved n-3 fatty acid status does not modulate insulin resistance in fa/fa Zucker rats

The objective was to examine the effect of polyunsaturated fatty acid type (plant vs fish oil-derived n-3, compared to n-6 fatty acids in the presence of constant proportions of saturated, monounsaturated and polyunsaturated fatty acids) on obesity, insulin resistance and tissue fatty acid composition in genetically obese rats. Six-week-old fa/fa and lean Zucker rats were fed with a 10% (w/w) mixed fat diet containing predominantly flax-seed, menhaden or safflower oils for 9 weeks. There was no effect of dietary lipid on obesity, oral glucose tolerance (except t=60 min insulin), pancreatic function or molecular markers related to insulin, glucose and lipid metabolism, despite increased n-3 fatty acids in muscle and adipose tissue. The menhaden oil diet reduced fasting serum free fatty acids in both fa/fa and lean rats. These data suggest that n-3 composition does not alter obesity and insulin resistance in the fa/fa Zucker rat model when dietary lipid classes are balanced.     

The impact of dietary fats,photoperiod, temperature and season on morphological variables,torpor patterns,and brown adipose tissue fatty acid composition of hamsters,Phodopus sungorus

We investigated how dietary fats and oils of different fatty acid composition influence the seasonal change of body mass, fur colour, testes size and torpor in Djungarian hamsters, Phodopus sungorus, maintained from autumn to winter under different photoperiods and temperature regimes. Dietary fatty acids influenced the occurrence of spontaneous torpor (food and water ad libitum) in P. sungorus maintained at 18°C under natural and artificial short photoperiods. Torpor was most pronounced in individuals on a diet containing 10% safflower oil (rich in polyunsaturated fatty acids), intermediate in individuals on a diet containing 10% olive oil (rich in monounsaturated fatty acids) and least pronounced in individuals on a diet containing 10% coconut fat (rich in saturated fatty acids). Torpor in P. sungorus on chow containing no added fat or oil was intermediate between those on coconut fat and olive oil. Dietary fatty acids had little effect on torpor in animals maintained at 23°C. Body mass, fur colour and testes size were also little affected by dietary fatty acids. The fatty acid composition of brown fat from hamsters maintained at 18°C and under natural photoperiod strongly reflected that of the dietary fatty acids. Our study suggests that the seasonal change of body mass, fur colour and testes size are not significantly affected by dietary fatty acids. However, dietary fats influence the occurrence of torpor in individuals maintained at low temperatures and that have been photoperiodically primed for the display of torpor.Abbreviations BAT brown adipose tissue - bm body mass - FA fatty acid(s) - MR metabolic rate - MUFA monounsaturated fatty acid(s) - PUFA polyunsaturated fatty acid(s) - SFA saturated fatty acid(s) - T _a air temperature - T _b body temperature - T_s body surface temperature(s) - TNZ thermoneutral zone - UFA unsaturated fatty acid(s)     

Fatty acid composition of depot fat of shorebirds collected at mid‐continental stopover sites during spring migration

ABSTRACT Despite the critical role of fat in providing energy for large‐scale seasonal movements, little is known about the fatty acid composition of shorebird depot fat. Fatty acid composition is important because it may impact flight performance and seasonal migratory movements. We analyzed the fatty acid composition of depot fat of 12 species of shorebirds collected during spring migration at stopover sites in Kansas from two different subcutaneous fat depots (furcular and saddle depots). Five fatty acids (palmitate [16:0], palmitoleate [16:1], stearate [18:0], oleate [18:1n‐9], and vaccenate [18:1n‐7]) accounted for 70–96% of the total composition of depot fat despite the diverse foraging behaviors of the species sampled. This similarity in fatty acid profiles may be due to a limited availability of high‐lipid food items in the shallow water and mudflat habitats where migratory shorebirds forage in the southern Great Plains. In addition, shorebird depot fat was composed primarily of long‐chain saturated and monounsaturated fatty acids (i.e., 16‐ and 18‐carbon), fatty acids thought to be more easily converted to energy during migration. Depot fat in the furcular depot was similar in composition to fat from the saddle depot, and we found no differences in fatty acid composition of the adipose tissue of males and females. Thus, our results suggest that representative shorebird depot fat fatty acid profiles can be obtained even if investigators are limited to sampling one sex, and that adipose tissue collected from saddle depots provide representative samples so biopsies can be limited to areas of the body with the least impact on flight performance.     

Dietary n-3 LCPUFA from fish oil but not α-linolenic acid-derived LCPUFA confers atheroprotection in mice

The atheroprotective potential of n-3 α-linolenic acid (ALA) has not yet been fully determined, even in murine models of atherosclerosis. We tested whether ALA-derived, n-3 long chain polyunsaturated fatty acids (LCPUFA) could offer atheroprotection in a dose-dependent manner. Apolipoprotein B (ApoB)^100/100LDLr^−/− mice were fed with diets containing two levels of ALA from flaxseed oil for 16 weeks. Fish oil- and cis-monounsaturated-fat-enriched diets were used as positive and negative controls, respectively. The mice fed cis-monounsaturated fat and ALA-enriched diets exhibited equivalent plasma total cholesterol (TPC) and LDL-cholesterol (LDL-c) levels; only mice fed the fish-oil diet had lower TPC and LDL-c concentrations. Plasma LDL-CE fatty acid composition analysis showed that ALA-enriched diets lowered the percentage of atherogenic cholesteryl oleate compared with cis-monounsaturated-fat diet (44% versus 55.6%) but not as efficiently as the fish-oil diet (32.4%). Although both ALA and fish-oil diets equally enriched hepatic phospholipids with eicosapentaenoic acid (EPA) and ALA-enriched diets lowered hepatic cholesteryl ester (CE) levels compared with cis-monounsaturated-fat diet, only fish oil strongly protected from atherosclerosis. These outcomes indicate that dietary n-3 LCPUFA from fish oil and n-3 LCPUFA (mostly EPA) synthesized endogenously from ALA were not equally atheroprotective in these mice.     

Effects of Temperature and Dietary Lipids on Phospholipid Fatty Acids and Membrane Fluidity in Steinernema carpocapsae

The phospholipid composition of Steinernema carpocapsae was studied in relation to diet and culture temperature. When reared at 18 and 27.5 C on Galleria mellonella or on an artificial diet supplemented with lard, linseed oil, or fish oil as lipid sources, nematode phospholipids contained an abundance of 20-carbon polyunsaturated fatty acids, with eicosapentaenoic acid (20:5(n - 3)) predominant, regardless of the fatty acid composition of the diet. Because the level of linolenic acid (18:3(n - 3)) in nematode phospholipids was very low and because eicosapentaenoic acid was present even when its precursor (linolenic acid) was undetectable in the diet, S. carpocapsae likely produces n - 3 polyunsaturated fatty acids by de novo biosynthesis, a pathway seldom reported in eukaryotic animals. Reduction of growth temperature from 25 to 18 C increased the proportion of 20:5(n - 3) but not other polyunsaturated fatty acids. A fluorescence polarization technique revealed that vesicles produced from phospholipids of nematodes reared at 18 C were less ordered than those from nematodes reared at 27.5 C, especially in the outermost region of the bilayer. Dietary fish oil increased fluidity in the outermost region but increased rigidity in deeper regions. Therefore, S. carpocapsae appears to modify its membrane physical state in response to temperature, and eicosapentaenoic acid may be involved in this response. The results also indicate that nematode membrane physical state can be modified dietarily, possibly to the benefit of host-finding or survival of S. carpocapsae at low temperatures.     

Study on chemical composition and physical properties of the Hamri (Barbus luteus) and Balaout (Chondrostoma regium) fish meat,oil and impact of its oils on cholesterol,triglyceride, HDL and blood sugar of laboratory rats

The study aimed at investigating the meat chemical composition and physical properties of oil of the Hamri (Barbus luteus) and Balaout (Chondrostoma regium) fish and its oil content or fatty acids, and also to know the impact of its oils on the level of cholesterol, triglyceride, high density lipoprotein (HDL) and blood sugar levels of laboratory rats. The study area extended from the province of Shirqat and Balad district to the province of Salah al-Din. The approximate percentages of meat from Hamri were 72.13, 19.74, 5.07 and 1.60 % for the moisture, protein, fat and ash respectively, and 71.63, 19.98, 4.96 and 2.04% respectively from Balaout. The extract oil from 2 types of fish differed significantly in Iodine value, Peroxide value, and Acid value and in saponification number. The fatty acids profiles results showed that oils from Hamri and Balaout fish meat consisted of 44.31 and 55.76% of Saturated fatty acid, 36.10 and 25.41% of poly unsaturated fatty acid, and 18.17 and 25.41% poly unsaturated fatty acids respectively. The experiment laboratory rats showed decreases in cholesterol, triglyceride and blood sugar level, and increases in high density lipoprotein (HDL). In conclusion, it is recommended that this oil can be used in human diet for health benefits.     

Effects of fish oil supplementation on prostaglandins in normal and tumor colon tissue: modulation by the lipogenic phenotype of colon tumors

Dietary fish oils have potential for prevention of colon cancer, and yet the mechanisms of action in normal and tumor colon tissues are not well defined. Here we evaluated the impact of the colonic fatty acid milieu on the formation of prostaglandins and other eicosanoids. Distal tumors in rats were chemically induced to model inflammatory colonic carcinogenesis. After 21 weeks of feeding with either a fish oil diet containing an eicosapentaenoic acid/ω-6 fatty acid ratio of 0.4 or a Western fat diet, the relationships between colon fatty acids and prostaglandin E₂ (PGE₂) concentrations were evaluated. PGE₂ is a key proinflammatory mediator in the colon tightly linked with the initiation and progression of colon cancer. The fish oil vs. the Western fat diet resulted in reduced total fatty acid concentrations in serum but not in colon. In the colon, the effects of the fish oil on fatty acids differed in normal and tumor tissue. There were distinct lipodomic patterns consistent with a lipogenic phenotype in tumors. In tumor tissue, the eicosapentaenoic acid/arachidonic acid ratio, cyclooxygenase-2 expression and the mole percent of saturated fatty acids were significant predictors of inter-animal variability in colon PGE₂ after accounting for diet. In normal tissues from either control rats or carcinogen-treated rats, only diet was a significant predictor of colon PGE₂. These results show that the fatty acid milieu can modulate the efficacy of dietary fish oils for colon cancer prevention, and this could extend to other preventive agents that function by reducing inflammatory stress.     

Comparative evaluation of rumen‐protected fat,coconut oil and various oilseeds supplemented to fattening bulls

The effects of five different dietary fat supplements on fatty acid composition and oxidative stability of subcutaneous and kidney fat were evaluated in 36 Brown Swiss bulls and compared to a low fat diet in a monofactorial design. The following fat supplements were provided as additional fat at 30 g per kg feed dry matter: crystalline rumen‐protected fat, coconut oil, and three types of crushed whole oilseeds (rapeseed, sunflower seed and linseed). Adipose tissues reflected differences (P < 0.05) in dietary fatty acid composition although to a lower extent. Using protected fat, which contained elevated levels of trans fatty acids, and sunflower seed, containing a high proportion of linoleic acid, significantly increased C18:1 trans fatty acid proportion in the adipose tissues. The use of sunflower seed increased conjugated linoleic acid. The oilseeds resulted in lower amounts of C16:0 in favour of C18:0. Except for linseed, all fat supplemented groups improved oxidative stability of adipose tissues as compared with control. This was explained by lower proportions of unsaturated fatty acids in adipose tissue (protected fat), by elevated α‐tocopherol contents (rapeseed, sunflower seed) or by a combination of both (coconut oil). Fat colour remained unaffected by treatments. Compared to other fat supplements oilseeds, especially sunflower seed and rapeseed, can therefore be recommended to be fed to bulls in order to increase the proportions of C18 unsaturated fatty acids in adipose tissues and to maintain or improve oxidative stability.     

Alteration of rat adipose tissue lipolytic response to norepinephrine by dietary fatty acid manipulation.

The present study clearly shows that, by feeding rats a semi-synthetic diet of known composition enriched with saturated fatty acids, the epididymal fat pad responsiveness to norepinephrine $\text{in}\text{vitro}$ can be abolished relative to fat pads from animals fed a similar diet but enriched with polyunsaturated fatty acids. Addition of varying concentrations of norepinephrine to the incubation medium produced a clear dose-response relationship in fat pads from animals fed diet enriched with polyunsaturated fatty acids while no effect of norepinephrine was apparent at any dose level in fat tissue from animals fed saturated fatty acids. These changes in lipolytic responsiveness were concurrent with alterations in fatty acid compositions of adipose tissue phospholipids and triglycerides as well as in total tissue contents of phospholipids and cholesterol.     

Influence of low ambient temperature and dietary lipids on adipose tissue and plasma fatty acid composition of the Japanese quail.

Japanese quail were maintained on synthetic diets containing 15% corn oil, 15% tallow, and zero fat, and were later exposed at 3.5 degrees C for 21 days. A distinct influence of dietary fat composition upon the adipose tissue triglyceride fatty acid composition was detected, but no change in fatty acid composition was produced with cold exposure. The fatty acid composition of adipose tissue from quail acclimatized to winter temperatures showed no trend towards a greater degree of unsaturation. There was no evidence of a gross selective mobilization of certain fatty acids from the depot lipids. Regional variation in the fatty acid composition of avian fats is discussed with respect to the level of food intake and body temperature.     

Lipid metabolism in fatty liver of lysine- and threonine-deficient rats

Rats were fed a low protein diet deficient in and supplemented with lysine and threonine. Liver lipids contained more lecithin, sphingomyelin, and free fatty acids, and less amino phospholipids in the deficient rats. No variations in fatty acid composition of choline- and ethanolamine-containing phospholipids were found; only palmitic acid was increased in the serine-containing phospholipids of the deficient animals. The incorporation of acetate-(14)C into phospholipids, but not into other liver lipids, was lower in deficient rats. In the plasma of deficient rats the concentration of esterified fatty acids and phospholipids was lower, of free fatty acids higher, than in the controls. The fatty acid composition of depot fat differed from that of liver neutral fat both in deficient and supplemented animals. The results presented establish that multiple metabolic defects resulting from lysine and threonine deficiency accompany the fatty liver. The design of the experiments does not permit conclusions to be drawn regarding the causal relationship between the various alterations in lipid metabolism and the fatty liver.     

Fatty liver produced by dietary deficiencies: its pathogenesis and potentiation by ethanol

In a study of the pathogenesis of hepatic fat accumulation under experimental conditions mimicking chronic alcoholism, rats were fed a low-fat diet, deficient in amino acids and choline, containing either ethanol or isocaloric amounts of carbohydrate. Dietary deficiencies alone produced a moderately fatty liver after 24 days. The combination of ethanol and dietary deficiencies resulted in enhanced lipid accumulation, which was apparent after only 11 days. In an investigation of the origin of hepatic triglyceride fatty acids, the experiment was repeated after the adipose lipids had been marked by the feeding of oils containing characteristic fatty acids (linseed oil, containing linolenate, or coconut oil, containing laurate and myristate). In all animals, the fatty acid composition of the hepatic triglycerides differed markedly from that of adipose tissue; it had a larger percentage of endogenously synthesized fatty acids and a five times smaller percentage of the marker fatty acids. In addition, ethanol feeding resulted in a greater retention of the marker fatty acids in the adipose tissue. Thus, the deposition of hepatic triglycerides produced by the feeding of deficient diets is markedly potentiated by ethanol; the triglyceride fatty acids accumulated under these conditions appear to originate, for the most part, not from mobilization of depot fat, but from endogenous synthesis.     

Use of re-esterified palm oils,differing in their acylglycerol structure,in fattening pig diets

Re-esterified oils are new fat sources obtained from the chemical esterification of acid oils with glycerol (both economically interesting by-products from oil refining and biodiesel industries, respectively). The different fatty acid (FA) positional distribution and acylglycerol composition of re-esterified oils may enhance the apparent absorption of saturated fatty acids (SFA) and, therefore, their overall nutritive value, which might lead to an increased deposition of SFA. The aim of the present study was to investigate the potential use of re-esterified palm oils, in comparison with their corresponding acid and native oils in fattening pig diets, studying their effects on fatty acid apparent absorption, acylglycerol and free fatty acid (FFA) composition of feces, growth performance, carcass-fat depots and fatty acid composition of backfat. Seventy-two crossbred boars and gilts (average weight of 24.7±2.55 kg) were blocked by initial BW (nine blocks of BW for each gender), housed in adjacent individual boxes, and fed one of the four dietary treatments, which were the result of a basal diet supplemented with 4% (as-fed basis) of native palm oil (PN), acid palm oil (PA), re-esterified palm oil low in mono- and diacylglycerols (PEL), or re-esterified palm oil high in mono- and diacylglycerols (PEH). Regarding results from the digestibility balance, PA and PN showed similar apparent absorption coefficients (P>0.05), despite the high, FFA content of the former. However, re-esterified palm oils (both PEL and PEH) showed a higher apparent absorption of total FA than did their corresponding native and acid oils (P<0.001), mainly due to the increased apparent absorption of SFA (P<0.001). This resulted in a greater feed efficiency and an increased deposition of SFA in backfat of pigs fed PEH, when compared with those fed PA (P<0.05), although no differences were found for carcass-fat depots (P>0.05). We conclude that re-esterified oils are interesting fat sources to be considered in fattening pigs.