Total Body Lipid Research Articles

Estimation of dioxin and furan elimination rates with a pharmacokinetic model.

Quantitative description of the pharmacokinetics of dioxins and furans in humans can be of great help for the assessment of health risks posed by these compounds. To that the elimination rates of sixteen 2,3,7,8-chlorinated dibenzodioxins and dibenzofurans are estimated from both a longitudinal and a cross-sectional data set using the model of Van der Molen et al. [Van der Molen G.W., Kooijman S.A.L.M., and Slob W. A generic toxicokinetic model for persistent lipophilic compounds in humans: an application to TCDD. Fundam Appl Toxicol 1996: 31: 83-94]. In this model the elimination rate is given by the (constant) specific elimination rate multiplied with the ratio between the lipid weight of the liver and total body lipid weight. Body composition, body weight and intake are assumed to depend on age. The elimination rate is, therefore, not constant. For 49-year-old males, the elimination rate estimates range between 0.03 per year for 1,2,3,6,7,8-hexaCDF to 1.0 per year for octaCDF. The elimination rates of the most toxic congeners, 2,3,7,8-tetraCDD, 1,2,3,7,8-pentaCDD, and 2,3,4,7,8-pentaCDF, were estimated at 0.09, 0.06, and 0.07, respectively, based on the cross-sectional data, and 0.11, 0.09, and 0.09 based on the longitudinal data. The elimination rates of dioxins decrease with age between 0.0011 per year for 1,2,3,6,7,8-hexaCDD and 0.0035 per year for 1,2,3,4,6,7,8-heptaCDD. For furans the average decrease is 0.0033 per year. The elimination rates were estimated both from a longitudinal and a cross-sectional data set, and agreed quite well with each other, after taking account of historical changes in average intake levels.

Producing extra eggs does not deplete macronutrient reserves in European Starlings Sturnus vulgaris

Recent studies have suggested that the size of avian clutches may be determined in part by the costs of egg production, which are thought to involve the depletion of endogenous nutrient reserves. I tested the hypothesis that producing extra eggs would deplete protein and lipid reserves in a passerine species, the European Starling Sturnus vulgaris. The first three eggs of clutches were removed on the days they were laid to induce females to lay extra eggs. Females responded to this manipulation by laying, on average, 1.3 eggs more than controls. However, based on the distribution of clutch sizes, it appears that some females responded to the removal of three eggs by producing more than one extra egg, whereas others responded by laying no extra eggs or by deserting. In unmanipulated females, the lean dry mass of the flight muscles and total body lipid were found to decline throughout breeding, an observation which is often interpreted as evidence that egg production depletes endogenous reserves. However, females experimentally induced to produce an extra egg did not have reduced stores of protein or lipid at clutch completion. No effect was observed in starlings even though this study had substantial (80%) power to detect a change in protein reserves of the same magnitude as that observed in a previous study of gulls. The decrease in flight muscle mass that has frequently been observed during breeding in passerines may not be due simply to mobilization of endogenous protein reserves.

Weight cycling-induced alteration in fatty acid metabolism.

Epidemiological studies have suggested that repeated weight cycling over time may increase the risk of coronary heart disease. The mechanism involved remains poorly understood, but the change in lipid metabolism during weight cycling has been offered as a possible explanation. The present study investigated the effect of weight cycling on the size and fatty acid composition of rat fat pads as well as serum cholesterol, triglyceride, glucose, insulin, and glucagon in rats. Two consecutive weight cycles were induced by 40% energy restriction followed by ad libitum refeeding of either a moderate-fat (MF; 22% energy) or a high-fat (HF; 45% energy) diet. The lipogenic enzymes, including fatty acid synthase, acetyl-CoA carboxylase, malic enzyme, pyruvate kinase, and lipoprotein lipase in the weight-cycled (WC) rats fed only the HF diet, yielded an overshoot of activities at the end of two weight cycles. These changes were accompanied by an 80% increase in the size of the adipocyte and a 40-50% increase in the size of perirenal and epididymal fat tissues in HF-WC rats. Regardless of whether the rats were fed the HF or MF diet, all WC rats showed a gradual reduction in linoleic and alpha-linolenic acid and an increase in palmitic, palmitoleic, and stearic acid in total body lipid. It is concluded that weight cycling in rats may promote body fatness if an HF diet is consumed and can significantly alter whole body fatty acid balance irrespective of whether they consumed an MF or HF diet. Most importantly, the weight cycling led to an overshoot or fluctuation of serum cholesterol, triglyceride, glucose, insulin, and glucagon. If weight cycling is associated with an increased risk of cardiovascular disease, then, part of the mechanism may involve the changes in these risk factors.

STELLER SEA LION BODY CONDITION INDICES

AbstractWe evaluated various measurements of mass, morphology, and blubber thickness as indices of fatness for Steller sea lions by correlation with the percentage of total body mass comprised by the sculp (%SCULP). We concluded LMD‐index was the best index evaluated because it had a relatively high r2 (0.58), had a linear relationship with %SCULP, and the intercept term was not different from O. We suggest the development of a LMD‐index for otariids would likely reduce the unexplained variation in the index. We developed a multiple regression model (r2= 0.745, P < 0.001) for predicting %SCULP with LMD‐index and functions of sex, age, and season as predictor variables. Steller sea lions < 5 yr of age had higher %SCULP values than those ≥ 5 yr. %SCULP declined with age for sea lions < 5 yr. Both younger and older males were fatter during the winter/spring period than during summer/ fall. Females of both age classes had similar %SCULP values throughout the year. Steller sea lions are relatively lean pinnipeds; estimates of blubber and total body lipids ranged from 5% to 17% of total body mass.

Animal-intrinsic variation in the partitioning of body protein and lipid in growing pigs

AbstractBody composition in the pig, and its variation, is mostly referred to in terms of body protein and lipid content of the whole body. This study was made to check for animal-intrinsic variation in the partitioning of body protein into protein pools and of body lipid into lipid depots. Results from serial slaughter trials on 316 Danish Landrace and 76 Danish Yorkshire pigs were used to estimate additive genetic and litter-associated variance components for several traits. These traits were total body protein and lipid mass (TOTPROT and TOTLIPD), the proportions of total body protein that are present in the muscles (PROTMUS) or in the (sub-)cutaneous tissue plus bones (connective tissue protein, PROTCON), and the proportions of total body lipid that are present in the (sub-)cutaneous tissue (LIPDSUB), in the muscles (inter- and intramuscular fat, LIPDMUS), or in the bones (LIPDBON). TOTPROT and TOTLIPD were adjusted by regression for body weight; PROTMUS and PROTCON were adjusted for PROTCON, and LIPDSUB, LIPDMUS and LIPDBON were adjusted for TOTLIPD. The pooled estimates (± s.e.) of the degree of genetic determination (the sum of the additive genetic and litter-associated variance components, which approximates the repeatability) of these traits were 0·48 ± 0·19 for TOTPROT, 0·56 ± 0·20 for TOTLIPD, 0·56 ± 0·12 for PROTMUS, 0·57 ± 0·15 for PROTCON, 0·32 ± 0·10 for LIPDMUS, 0·33 ± 0·12 for LIPDSUB, and 0·22 ± 0·10 for LIPDBON. It is concluded that there is animal-intrinsic variation in partitioning of body protein and lipid.

Determining body fuels of wintering mallards

Measuring body lipids and proteins of wild animals such as mallards is essential to determine the impact of the environment on their body condition. A major difficulty, however, is that biochemical analysis of carcass is tedious and therefore cannot be applied at a large scale. The main objective of this study was therefore to find out if simple measurements can be used as indices of total body lipids and proteins. Four classes of lipid and protein indices, derived on a ‘source’ group, were defined according to their complexity and condition of application (field or laboratory). Accuracy of the indices was evaluated on an independent group, of which the body composition calculated from indices was compared to carcass analysis. In live birds, body mass was an accurate and convenient predictor for both lipid and protein masses. If carcasses are available, extensive analysis provides a higher accuracy for body lipids only. This can be simply obtained through multiple regressions using abdominal fat mass and/or dry body mass.

Effect of Dietary Protein Level on Growth and Blood Parameters in Summer Flounder, Paralichthys dentatus

Summer flounder, Paralichthys dentatus, were fed diets with various protein levels (36.6%, 40.0%, 47.7%, 51.9%, and 56.5%), and the effect of these levels on growth and blood parameters was measured. Fish fed the highest protein level gained significantly (P< 0.05) more weight than those fed lower levels of protein. There were no significant (P> 0.05) differences among mean feed conversion ratios (FCR), protein efficiency ratios (PER), net protein utilization (NPU), or mean percent total body moisture, protein, lipid, or ash content. Fish fed diets with 52 or 56% protein had red blood cell counts that were significantly (P< 0.05) higher than fish fed diets with lower protein levels. In addition, hematocrits were significantly (P< 0.001) correlated to dietary protein. There were no significant differences among mean total protein, triglyceride, glucose or phosphate. However, blood calcium levels varied with diet. Data indicate that summer flounder protein requirements are near those suggested for other flatfish.

Temporal variation in body composition and lipid storage of the overwintering, subarctic copepod Neocalanus plumchrus in the Strait of Georgia, British Columbia (Canada)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 192:239-247 (2000) - doi:10.3354/meps192239 Temporal variation in body composition and lipid storage of the overwintering, subarctic copepod Neocalanus plumchrus in the Strait of Georgia, British Columbia (Canada) Melissa Evanson1,*, Elizabeth A. Bornhold2, Robert H. Goldblatt3, Paul J. Harrison3, Alan G. Lewis3 1Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada 2Ocean Science and Productivity, Institute of Ocean Sciences, 9860 West Saanich Rd, Sidney, British Columbia V8L 4B2, Canada 3Department of Earth and Ocean Sciences (Oceanography), University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada *E-mail: mevanson@uoguelph.ca ABSTRACT: Neocalanus plumchrus (Marukawa) was sampled between October 1996 and August 1997 in the upper 400 m of the water column in Strait of Georgia (49° 15' N, 123° 45' W), a large, partly enclosed basin in British Columbia, Canada. The overwintering vertical stage distribution of N. plumchrus is described together with the temporal variations in total body length, dry weight, lipid and body composition in copepodite stage V (CV) and adult females. Adult males and females were found at depths of less than 200 m from January to March. Regressions of total body length to total dry weight showed significant correlations for CVs and females. Carbon and nitrogen isotopic analysis (δ15N and δ13C) indicated no temporal increase, suggesting a lack of feeding in CVs (October to December) and females (January to March) at depth and a dependency on stored lipid reserves accumulated during times of high primary production in the euphotic zone. Total lipid content per individual copepod showed significant decreases from 0.5 to 0.2 mg during the time of adult female gonadal development between January and February. A decrease in total dry mass per copepod from 0.9 to 0.4 mg also occurred during this time period. Lipid composition showed preferential retention of long-chained fatty acids until the onset of egg release in March. Significant decreases in carbon and nitrogen from January to February and, to a lesser extent, between February and March were observed, corresponding to periods of gonad maturation and egg release, respectively. Significant increase in nitrogen content suggests the possibility of bacterial ingestion by late moulting CVs. The significant decrease in C:N ratio, from 8.7 to 4.1, suggests a depletion of lipid reserves and resultant reliance on proteins as an energy source for egg release. Variations in organic content verify that the CVs remain in a state of dormancy in which minimal lipid reserves are depleted, while the onset of maturation and reproduction is the major energy consumer. KEY WORDS: Neocalanus plumchrus · Lipid · Body composition · Vertical distribution · Temporal variation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 192. Publication date: January 31, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Growth Responses, Tissue Composition, and Liver Enzyme Changes in Juvenile Sunshine Bass, Morone chrysops × M. saxatilis, Associated with Dietary Protein and Lipid Level

ABSTRACT Four isocaloric, semi-purified diets containing low (30%) or high (50%) protein with either 12 or 18% lipid were fed at 4% of body weight to juvenile sunshine bass, Morone chrysops ×M. saxatilis, for 12 weeks (initial weight = 3.4 g). Fish fed the high protein diets gained significantly more weight and had better feed conversions than fish fed low protein diets. There were no significant differences in muscle or total body moisture and lipid or in intraperitoneal fat associated with either dietary protein or lipid levels. However, muscle protein and liver lipid increased significantly at high protein and lipid levels, respectively. Liver alanine amino transferase activities increased significantly at the high dietary protein and lipid levels, indicating that excess dietary protein was being used for non-protein processes. Fruc-tose-1,6-diphosphatase and pyruvate kinase activities indicated that excess dietary protein was not being used to synthesize glucose or glyco-gen. Malic enzyme activities decreased in response to increased dietary lipid, but did not respond to changes in dietary protein, indicating that excess protein was not being used for lipid synthesis. It is hypothesized the excess dietary protein is used for energy production.

Lipids of the notothenioid fishes Trematomus spp. and Pagothenia borchgrevinki from East Antarctica

The notothenioid fishes Trematomus pennellii, T. newnesi, and T. bernacchii had 5–15% skeletal lipid, as percent dry weight, and this comprised 6–8% of the total body lipid. Trematomus hansoni and Pagothenia borchgrevinki had 2–4% skeletal lipid, which comprised 1% of total body lipid. Triacylglycerol was the major lipid class present in all tissues of all fish analyzed (up to 89% of total lipid), with minor components including sterol, phospholipid and wax esters. Monounsaturated fatty acids comprised 38.3–58.0% of the total fatty acids, and included primarily oleic [18 : 1(n-9)] and palmitoleic [16 : 1(n-7)] acids. Polyunsaturated fatty acids comprised 19.1–40.0% of the total fatty acids and included primarily eicosapentaenoic acid [20 : 5(n-3)] and docosahexaenoic acid [22 : 6(n-3)]. These five notothenioid fishes, which include benthic, benthopelagic, and cryopelagic species, are lower in lipid than other important Southern Ocean fishes (such as the Patagonian toothfish) and are estimated to be negatively buoyant. These data will be of use to research groups presently using signature lipid methodology.

Growth, feed utilization and body lipid content of gilthead seabream ( Sparus aurata) fed increasing lipid levels and fish meals of different quality

The present study shows the effects of feeding gilthead seabream, 70 to 400 g, with nine diets containing three different lipid levels (15, 22 and 28% on a dry weight basis), combined with two types of fish meal of different quality. In addition, feed processing effects (extruded vs. pelletized) were also compared for the diet containing 22% lipid. The diets prepared with the high quality fish meal promoted better growth than those prepared with the low quality one. Protein utilization was enhanced by a sparing effect of dietary lipid at 22%. This lipid level needed to be increased up to 28% with low quality meal to effectively spare dietary protein. A significant increase in fish growth with higher dietary lipid levels, in both high and low quality fish meal diets, was only related to a significant increase in total body lipid content in high quality fish meal diets, and an excess of lipid may have been the cause of hepatocyte abnormalities in fish fed the highest lipid levels. The effect of pellet processing was apparent in low quality fish meal diets, where a significantly better growth performance was obtained in fish fed the extruded diet. There were no significant differences among all treatments in feed intake, and values were similar to those suggested by commercial fish feed producers, for similar fish size and water temperatures. Values for feed conversion ratio (FCR) were lower than 1.6 for all diets.

Spatial and temporal variation in lead levels related to body condition in the Mississippi Valley population of Canada geese.

Concern over lead poisoning led to progressive prohibition of toxic shot to harvest waterfowl in the 1980's. Nevertheless, waterfowl remain susceptible to ingestion of lead shot because illegal use continues and spent shot persists in soil and wetland substrates. While mortality due to lead toxicosis has subsided, sublethal effects may still affect survival and reproduction. We measured liver lead levels and body condition in 732 Canada geese (Branta canadensis interior) during July 1984 to April 1989 in southern Illinois (USA), east-central Wisconsin (USA), and northern Ontario (Canada). Although we sampled only individuals that were visibly healthy, 55 of 732 (7.5%) geese had elevated liver lead levels (> 2 ppm). Lead levels of 46 (6.3%) geese indicated subclinical poisoning (2-6 ppm) and 9 (1.2%) geese had lead levels indicative of clinical poisoning (> 6 ppm). A greater proportion of juveniles (14.3%) had elevated lead levels than did adults (6.0%), but there was no difference between genders. Lead levels were highest in autumn and winter in southern Illinois, but were low during nesting and summer, despite legal use of lead shot in northern Ontario during our study. Lead poisoning (> or = 5% of the population) was still evident during all seasons in juveniles, and during autumn and winter in adults, 5 to 10 yr after toxic shot was banned from areas where we collected geese during migration and winter. Elevated lead levels did not affect total body mass, lipid reserves, or mineral levels of geese we collected. Protein levels also were unaffected below 10 ppm, but there was evidence of decline at higher concentrations. Thus, it seems unlikely that lead exposure currently affects survival or reproduction of Mississippi Valley Population (MVP) geese via body condition, although other sublethal effects cannot be discounted.

Relationship between abdominal visceral fat and metabolic risk factors in obese adolescents

The distribution of body fat may play an important role in determining the risk of obesity-related morbidity in obese adults. In view of the alarming increase in adolescent obesity, this article addresses whether defects in insulin action and secretion and increased intra-abdominal fat that typify central obesity in adults are expressed early in the course of developing obesity. The euglycemic hyperinsulinemic clamp technique with stable isotopes was used to determine insulin effects on glucose and glycerol turnover in obese and lean adolescents. The hyperglycemic clamp was used to quantitate insulin secretion, while magnetic resonance imaging was used to directly assess abdominal subcutaneous and visceral fat. The results indicate that obese adolescent girls have the following characteristics: 1) insulin resistance with major defects in oxidative and nonoxidative glucose metabolism; 2) hyperinsulinemia in the fasting state and in response to intravenous glucose; and 3) impaired suppression of total body lipid oxidation and plasma FFA concentrations in response to insulin. Am. J. Hum. Biol. 11:259–266, 1999. © 1999 Wiley-Liss, Inc.

Relationship between abdominal visceral fat and metabolic risk factors in obese adolescents.

The distribution of body fat may play an important role in determining the risk of obesity-related morbidity in obese adults. In view of the alarming increase in adolescent obesity, this article addresses whether defects in insulin action and secretion and increased intra-abdominal fat that typify central obesity in adults are expressed early in the course of developing obesity. The euglycemic hyperinsulinemic clamp technique with stable isotopes was used to determine insulin effects on glucose and glycerol turnover in obese and lean adolescents. The hyperglycemic clamp was used to quantitate insulin secretion, while magnetic resonance imaging was used to directly assess abdominal subcutaneous and visceral fat. The results indicate that obese adolescent girls have the following characteristics: 1) insulin resistance with major defects in oxidative and nonoxidative glucose metabolism; 2) hyperinsulinemia in the fasting state and in response to intravenous glucose; and 3) impaired suppression of total body lipid oxidation and plasma FFA concentrations in response to insulin. Am. J. Hum. Biol. 11:259-266, 1999. Copyright 1999 Wiley-Liss, Inc.

Growth and body composition of highly selected boars and gilts

AbstractAn experiment was conducted to measure the growth and body composition changes of highly selected boars and gilts from 10 to 150 kg live weight. Thirty boars and 30 gilts were given food ad libitum and two pigs of each sex were slaughtered at 10-kg increments from 10 kg to 150 kg live weight at which time the chemical composition of the body was determined. Boars and gilts exhibited different patterns of growth, nitrogen deposition rate (NDR) and lipid deposition rate (LDR) with boars exhibiting a sharp peak in daily live-weight gain and NDR while gilts exhibited almost a flat response curve over the age and weight range tested. Gilts experienced a peak in LDR at a lighter weight than boars (75·8 v. 100·5 kg) while NDR peaked at the same weight for both sexes (70·8 kg). Maximum NDR for boars and gilts was 37·7 and 28·1 glday (235·5 and 175·5 glday protein deposition rate) respectively. The Gompertz growth equation [Y = A + C × EXP (−EXP (−B ×(X−M)))] was shown to accurately represent the growth trajectory, while the logarithmic derivative of the allometric equation [Y = aXb] was used to determine live weight and body composition relationships. Combined sex relationships indicated that total body nitrogen and lipid concentrations increased at the same rate. A quadratic equation for the prediction of NDR based on live weight was developed for this genotype (NDR = 24·06 + 0·34 W − 0·002W2). In conclusion, the results provide a basis for comparison of body composition and growth patterns between the highly selected genotype tested and pigs from other genetic backgrounds. Sex effects exist for growth and body composition but combined sex prediction equations can be used to estimate NDR potential.

Postabsorptive respiratory quotient and insulin-stimulated glucose storage rate in nondiabetic pima indians are related To glycogen synthase fractional activity in cultured myoblasts.

A decreased ratio of fat to carbohydrate oxidation rate (an elevated respiratory quotient) predicts the development of obesity. Skeletal muscle accounts for a major fraction of total body lipid oxidation and is the principle site for reduced glucose storage in insulin-resistant subjects. The potentially important role that muscle has in promoting obesity or insulin resistance may be based on metabolic control intrinsic to skeletal muscle. Cultured skeletal muscle provides a system to examine the importance of inherent metabolic traits in muscle biopsies from obese and insulin-resistant subjects. Glycogen synthase fractional activity (GSFA) was measured in cultured myoblasts from 21 Pima Indians characterized in vivo using indirect calorimetry and a euglycemic hyperinsulinemic clamp. Basal GSFA in cultured muscle cells is inversely correlated with postabsorptive respiratory quotient of the muscle donors (r = -0.66, P = 0.001) and with in vivo high dose insulin-stimulated glucose storage rates (r = 0.47, P = 0.04). These results indicate that the postabsorptive respiratory quotients and insulin-mediated glucose storage rates in vivo share a common regulatory mechanism with GSFA in cultured myoblasts. Abnormal regulation of glycogen synthase phosphorylation state may be an intrinsic defect in skeletal muscle associated with obesity and insulin resistance.

Total body lipid and triglyceride response to energy deficit: relevance to body composition models.

Although the study of human body composition is advancing rapidly, confusion still prevails regarding the molecular-level lipid component. Most molecular-level body composition models are presently based on the overall hypothesis that nontriglyceride lipids constitute an insignificant proportion of total body lipid. A single lipid or "fat" component consisting of triglycerides is thus assumed in most molecular-level body composition models. To test this hypothesis, the present study, carried out in adult rats, was designed to examine two questions: 1) What is the proportion of total lipids as triglycerides? and 2) Is this proportion constant or does it change with negative energy balance and weight loss produced by calorie restriction and increased exercise? Results indicated that with negative energy balance and weight loss there were progressive losses of total body triglyceride and lipid. The proportion of total lipids as triglyceride was 0.83 +/- 0.08 (SD) in control animals, with reductions at 2 and 9 wk of energy restriction [0.82 +/- 0.04 (P = NS vs. control) and 0.70 +/- 0.15 (P = 0.05)] and at 9 wk for energy restriction plus exercise [0.67 +/- 0.09 (P = 0.003)]. Nontriglyceride lipids comprised 2.8% of carcass weight at baseline and decreased to 2.2% by 9 wk of energy restriction and exercise (P = NS). Substantial differences were observed between body composition ratios expressed as percentages of the lipid-free body mass (LFM) and triglyceride-free body mass (TGFM); (e.g., total body water/LFM and TGFM in controls = 72.7 +/- 0.7 and 70.4 +/- 2.2, respectively; P = 0.02). These observations strongly support the existence and importance of nontriglyceride lipids as a body composition component that responds independently from storage triglycerides, with negative energy balance produced by food restriction and exercise.

Comparison of native, lyso and hydrogenated soybean phosphatidylcholine as phospholipid source in the diet of postlarval penaeus japonicus bate

Native and two modified forms of soybean phosphatidylcholine were used to study the nutritional effect of their fatty acids for postlarval Penaeus japonicus. Five semipurified and isolipidic diets were formulated using casein as a protein source. Three diets contained 1.5 % of different types of phosphatidylcholine (95 % purity), i.e. native soybean phosphatidylcholine, hydrogenated soybean phosphatidylcholine and 1‐acyl lyso soybean phosphatidylcholine, besides 1% of n‐3 highly unsaturated fatty acid formulated as triglycerides. Two negative control diets contained either triglycerides or ethyl esters as a source of n‐3 highly unsaturated fatty acids without phospholipid. The experiment was conducted during two successive phases of 20 d starting from 12‐d old postlarvae. Feeding the diet containing native soybean phosphatidylcholine resulted in significantly better growth and resistance to osmotic shock of P. japonicus postlarvae compared to the other diets. The total lipid content of the tissue was significantly increased by the supplementation of soybean phosphatidylcholine, whereas no significant difference was observed for the shrimp fed the modified phosphatidylcholine sources compared to the phosphatidylcholine‐free diet at the end of the experiment. Shrimp fed the diet containing soybean phosphatidylcholine exhibited a higher polar lipid fraction in the whole body total lipid mainly as a result of the increased proportion of phosphatidylcholine and to a lesser extent of phosphatidylinositol at the expense of free fatty acids, free sterols and sterol esters. The content of 20: 5n‐3, 22 : 6n‐3 and total n‐3 highly unsaturated fatty acids in the shrimp tissue were higher in shrimp fed the native soybean and hydrogenated soybean phosphatidylcholine diets compared to those fed the phosphatidylcholine‐free and 1‐acyl lyso soybean phosphatidyl‐choline‐based diets. The fatty acid profile of tissue phosphatidylethanolamine was more influenced by the type of dietary phosphatidylcholine than that of tissue phosphatidylcholine. In the absence of phospholipids in the diet, triglyceride fish oil and a mixture of ethyl ester concentrate arid coconut oil with similar n‐3 highly unsaturated fatty acids content were equivalent sources of n‐3 highly unsaturated fatty acids. The beneficial effects of dietary phospholipids may be due to a more efficient transport and utilization of dietary neutral lipids through a better lipid mobilization following absorption in the intestinal mucosa rather than due to a better emulsification of neutral lipid in the gut lumen. The functionality of phosphatidylcholine in the diet of postlarval P. japonicus requires the presence of unsaturated fatty acids and an intact fatty acid moiety.

Lipid dynamics in anadromous Arctic charr, Salvelinus alpinus (L.): seasonal variations in lipid storage depots and lipid class composition

Changes in lipid class composition of tissues of anadromous Arctic charr, Salvelinus alpinus, were studied in relation to seasonal patterns of lipid deposition and lipid mobilisation. Charr of a north Norwegian population were collected in late May when fish were migrating towards the sea, and in mid-July when the fish re-entered fresh water. Some maturing fish captured in mid-July were held in captivity until late September to assess lipid dynamics associated with maturation. The carcass (head, fins, skeleton and skin) accounted for approx. 50% of the total body lipid content when the fish re-entered fresh water from the sea. Triacylglycerols (TAG) comprised 75-80% of the carcass lipid in ascending charr, confirming that the carcass is a major lipid depot. The skeletal muscle also represented a major lipid store: muscle of ascending charr contained 35-40% of the body lipids, with TAG being dominant (approx. 75% of muscle lipid). The gut (gastrointestinal tract and visceral lipid) and liver of ascending charr each held only 4-5%; of the body lipid, TAG being the dominant lipid class in both of these depots (Gut TAG: 60-65%; Liver TAG: 50-55%). Body lipid decreased 30-40% during maturation: lipids were depleted from all depots, but mobilisation of from the carcass and muscle was quantitatively the most important. In mature females, the ovaries held almost 25% of the body lipid, with the proportion of TAG exceeding that of polar lipids (PL)(TAG: 62%; PL 12.4%). In the mature males, the testes accounted for less than 3% of the total lipids. TAG tended to dominate the testis lipids (TAG: 29.5%), but there were also quite high proportions of free fatty acids, cholesterol and polar lipids (FFA: 23.5%; C: 15%; PL 9.7%). Females lost approx. 80% of their body lipid during spawning and overwintering, the majority of this being TAG. Males also lost large amounts of TAG during the winter, but in contrast to the females lipid depletion amounted to only 50-55% of that present at the time of ascent into fresh water.

Effect of dietary phospholipid on requirements for and incorporation of n − 3 highly unsaturated fatty acids in postlarval Penaeus japonicus Bate

Penaeus japonicus postlarvae were fed three dietary levels of n − 3 highly unsaturated fatty acids (HUFA) (0, 0.5 and 1%) with or without 1.5% soybean phosphatidylcholine (SPC; 95% purity). The experiment was conducted during two successive phases of 20 days starting with 12-day-old postlarvae. Supplying 1.5% of SPC and 1% n − 3 HUFA in the diet significantly improved the growth, survival and resistance to osmotic stress of postlarvae compared to those fed phosphatidylcholine (PC)-free and HUFA-free diets, respectively. A significant interaction between dietary SPC and n − 3 HUFA was only found for their effect on resistance to osmotic stress. A significant drop in stress sensitivity was obtained in the PC-deprived shrimp only when 1% n − 3 HUFA were present in the diet, whereas the shrimp fed SPC exhibited a drop of stress sensitivity already at a level of 0.5% n − 3 HUFA. Increasing the dietary levels of n − 3 HUFA resulted in increased concentrations in the shrimp tissue of total body lipid content, 20:5 n − 3 and 22:6 n − 3; and reduced levels of 18:2 n − 6 and total n − 6 polyunsaturated fatty acids. Also, the proportion of 20:5 n − 3, 22:6 n − 3 and total n − 3 HUFA significantly increased in the two major shrimp phospholipids, PC and phosphatidylethanolamine (PE), with increasing level of dietary n − 3 HUFA. The changes in whole body total lipid, lipid composition and fatty acid composition of total lipid, PC and PE due to the addition of soybean phospholipid depended on the dietary level of n − 3 HUFA.