Effects Of Dietary Lipids Research Articles

Effect of flaxseed oil, animal fat, and vitamin E supplementation on growth performance, serum metabolites, and carcass characteristics of finisher pigs, and physical characteristics of pork

Dietary lipid supplementation can reduce de novo lipogenesis and increase intramuscular fat content of pork simultaneously, and vitamin E supplementation can increase the oxidative stability of pork. A total of 96 pigs (Yorkshire) were used to investigate the effect of dietary lipid (0 or 1% flaxseed oil + 1, 3, or 5% poultry fat for diets supplemented with lipids) and vitamin E (11 or 220 IU/kg) supplementation in a 4 × 2 factorial arrangement of treatments on growth performance, serum metabolites, and carcass traits of finisher pigs, and physical characteristics of pork. Forty-eight pens containing 2 gilts or 2 castrated males per pen were randomly assigned to 8 diets with 3 gilt pens and 3 castrated male pens per treatment. Pigs were switched from finisher-1 [initial body weight (BW): 54.3 ± 3.4 kg] to finisher-2 diets when the average pen BW reached 84.1 ± 4.0 kg. Standardized ileal digestible Lys and Ca and P were adjusted with the DE content accordingly to maintain constant Lys, Ca, and P to DE ratios. Pigs were harvested when they reached the target BW of 110.0 ± 3.0 kg. There were no lipid x vitamin E interactions in growth performance. As dietary lipids increased from 0 to 6%, average daily feed intake decreased linearly (P < 0.018) and gain to feed ratio improved linearly (P < 0.001) during the finisher-1, finisher-2, and overall phases. Supplementation with 220 IU vitamin E/kg reduced the efficiency of feed, Lys, and DE utilization for BW gain (P < 0.036) during the finisher-1 and overall phases. As dietary lipids increased, serum cholesterol and triglyceride concentrations increased linearly (P < 0.003). Supplementation of the diet with 1% flaxseed oil + 1, 3, or 5% poultry fat resulted in greater serum total protein, albumin, cholesterol, and triglyceride concentrations (P < 0.037) compared with no lipid supplementation. Pigs fed the diets containing 0, 2, and 4% lipids and supplemented with 220 IU vitamin E/kg had greater 10th rib BF and lower fat-free lean than those fed the dies contained 11 IU vitamin E/kg, whereas 10th rib BF was lower and fat-free lean was greater in pigs those fed the diet containing 6% lipids and supplemented with 200 IU vitamin E/kg than those fed the diet contained 11 IU vitamin E/kg (lipid x vitamin E, P < 0.020). Dietary lipids had no effect on subjective marbling score and ether extract content of loin muscle or most other pork and loin muscle characteristics, but belly thickness and width increased (linear, P < 0.040) as dietary lipids increased. Vitamin E supplementation increased marbling score (P = 0.042), but it had no clear effect on loin muscle color (subjective, and L*, a*, and b*), ham and loin muscle pH, loin muscle characteristics, or belly firmness. As expected, feed intake decreased and feed efficiency improved progressively with increasing dietary lipid supplementation from 0 to 6%. Although there were interactions, dietary lipids seemed to have no clear effects on the carcass BF or fat-free lean. Similarly, dietary supplementation with 1% flaxseed oil + 1, 3, or 5% poultry fat had no effect on subjective marbling score or ether extract content of loin muscle. Supplementation with 220 IU vitamin E/kg increased carcass leanness with 6% dietary lipids, but increased carcass BF with 0 to 4% dietary lipids. Vitamin E supplementation increased subjective marbling score, but seemed to have no clear effects on loin muscle color, ham and loin muscle pH, loin muscle characteristics, or pork belly firmness.

Influence of long-term feeding of high-fat diet on quercetin and fat absorption from the small intestine in lymph duct-cannulated rats.

This study aimed to investigate the effect of dietary lipids and a long-term high-fat diet on lymphatic triglyceride and quercetin absorption in rats with a surgically implanted thoracic lymph cannula. Quercetin-3-O-β-glucoside reduced the lymphatic triglyceride output from the intestines; this reduction was prominent among rats fed a high-fat diet.

Effects of dietary lipid sources on hepatic nutritive contents, fatty acid composition and proteome of Nile tilapia (Oreochromis niloticus)

Dietary oils of varying fatty acid composition have been used in tilapia feeds; nevertheless, investigation of their effects on metabolism and physiological processes has been limited. Therefore, in this study, using proteomic technology, the effects of different dietary lipids (DLs) on hepatic lipid metabolism and physiological processes were investigaed in Nile tilapia (Oreochromis niloticus). Fish were fed with different DL, which included palm oil (PO), linseed oil (LO) and soybean oil (SBO) for 90 days. Growth performance appeared to be similar among the dietary group. Hepatic FA contents were reflected by DL. Dietary PO (source of saturated fatty acids; SFA) led to an increase in the hepatosomatic index as well as lipid and protein contents in liver. Dietary SBO (source of n-6 polyunsaturated fatty acids; n-6 PUFAs) increased hepatic carbohydrate contents, but decreased the hepatic protein. The proteomic analysis showed that these nutritive changes in the liver were mediated by several proteins involved in lipid, carbohydrate, and amino acid metabolism. Dietary SBO showed an increased accumulation in proteins related to oxidative stress, immune and inflammatory processes. Dietary LO (source of n-3 PUFAs) increased abundance of cytoskeleton-related proteins. qRT-PCR was performed to provide supportive information for the result of proteomic study. Similar effects of DLs on mRNA levels were observed for atp5b, krt18, and selenbp1. Combined together, dietary SFA could supply as energy reservoir for regular activites. Dietary n-3 and n-6 PUFAs led to induce vital metabolic and physiologic processes which would contribute to maintaining normal health and/or providing health-related benefits. SignificanceDietary SBO increased hepatic carbohydrate contents, but decreased the hepatic protein. Different dietary lipid led to alter the abundance of several proteins (i.e., DHRS1, ATP5B, PLA2G12B, APO, AMY2A, GRP78, PRSS1, FAH, and PRSS36) involved in lipid, carbohydrate, and amino acid metabolism. Dietary SBO showed an increased accumulation in proteins (i.e., QDPR, CABC1, and PRDX6) that respond to oxidative stress, suggesting that n-6 PUFAs induce oxidative conditions. Dietary SBO led to increase the accumulation of proteins (i.e., NITR26, NCCRP1, and LCN) involved in immune and inflammatory processes. Dietary LO increased the abundant levels of cytoskeleton-related proteins (i.e., ACTB, AHNAK, ERC2, KRT18, and RILP1). Other proteins (i.e., SELENBP1, FAM46C, and ANC1) involved in other physiological processes were also modulated by DL. qRT-PCR was performed to provide supportive information of proteomic study. Similar effects of DLs on mRNA levels were observed for atp5b, krt18, and selenbp1.

Dietary lipid and carbohydrate interactions: implications on growth performance, feed utilization and non-specific immunity in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂)

The present study was conducted to explore the effects of dietary lipid, carbohydrate and their interactions on growth performance, feed utilization, body composition and non-specific immunity of hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). Nine isoproteic diets were formulated with three levels of dietary lipid (7, 10 and 13%) and carbohydrate (8, 12 and 16%) in a 3 × 3 factorial design. Triplicate groups of 30 juvenile fish (initial weight, 21.48 ± 0.24 g) were fed each of the diets twice daily to apparent satiation for 8 weeks. Results showed that a significant interaction between dietary lipid and carbohydrate was observed in the specific growth rate (SGR), and the SGR of grouper was not affected by dietary lipid but decreased significantly with the increase of dietary carbohydrate. Thereinto, grouper fed the diet containing 10% lipid and 8% carbohydrate obtained the highest SGR. Higher dietary lipid or carbohydrate significantly decreased feed intake (FI), but significantly elevated feed efficiency ratio (FER) and protein efficiency ratio (PER). Additionally, the retention rate of protein (PRR) and lipid (LRR) were both significantly improved with increasing dietary lipid level, while LRR was significantly decreased as dietary carbohydrate content increased. Meanwhile, significant interactions between dietary carbohydrate and lipid occurred in feed utilization. The apparent digestibility coefficient (ADC) of starch was significantly reduced with the increase of dietary lipid or carbohydrate level, and the interaction was also significant. With grouper fed the diet with 8, 12 and 16% carbohydrate, the postprandial glucose content peaked at the 3, 6 and 12h time-points, respectively. The activity of serum lysozyme increased significantly with the increase of dietary lipid, but significantly decreased as dietary carbohydrate content increased, while it was not significantly affected by the interaction. In addition, grouper fed the diets with 10% lipid obtained the highest SOD activity, in which no significant difference was observed with the increase of dietary carbohydrate content. In above, a combination of 10% lipid and 8% carbohydrate in the diet for this grouper should be optimum.

The effect of dietary lipid on gut microbiota in a senescence-accelerated prone mouse model (SAMP8).

Gut microbiota change with aging and diet. In a previous study, it was shown that a moderate-fat diet enriched with fish oil had beneficial effects for elderly patients, so we examined the effect of this diet on aging-related changes in gut microbiota in this study. We used 3-month-old male senescence-accelerated prone mice (SAMP8). The mice were fed a normal diet containing 4g soybean oil/100g of diet for 6months and then divided into 4 groups: (1) the Baseline group, ended breeding at 6months old; (2) the Control group, continued on a normal diet until 15months old; (3) the MF group, switched to a moderate-fat diet until 15months old; and (4) the MF + FO group, switched to a moderate-fat diet enriched with fish oil until 15months old. When mice were 6 or 15months old, fecal samples were collected and gut microbiota analysis was performed. Gut microbiota analysis at the genus level showed that bacteria known to increase in association with fatty liver and intestinal inflammation increased with aging. However, this alteration was largely inhibited by the moderate-fat diet enriched with fish oil. On the other hand, there was a decrease with aging in the bacteria that play a role in energy consumption, but this alteration was inhibited by the moderate-fat diet enriched with fish oil. These results suggest that a moderate-fat diet enriched with fish oil has beneficial effects on gut microbiota in aging.

Effects of dietary lipid and protein levels on growth and physiological metabolism of Pelteobagrus fulvidraco larvae under recirculating aquaculture system (RAS)

A feeding trial was conducted to investigate the effects of different dietary lipid and protein levels on both the physiological metabolism and the anti-oxidation of Pelteobagrus fulvidraco larvae cultured in recirculating aquaculture system (RAS). In the present study, four test diets (P52L13, P52L9, P48L13, P48L9) were formulated by two different lipid levels (13%, 9%) and two different protein levels (52% and 48%) in a factorial manner (2 × 2) to provide four different dietary protein-lipid ratios (P:L) 3.95, 5.71, 3.56 and 5.46. Each treatment was assigned in triplicate. Two days after hatching, larvae were fed with Artemia sp. for 1 day, and then were co-fed the Artemia sp.plus the tested diets for 2 days, finally fed test diets for 18 days. The results were in keeping with that of growth performance, showed that the larvae fed on P52L13 and P48L9 diets had significantly higher activities of lipoprotein lipase (LPL), glutamic-pyruvic transaminase (GPT), superoxide dismutase (SOD) and catalase (CAT) than other two groups (P < 0.05). The highest activities of lysozyme (LZM) and glutathione (GSH) were observed in group P52L13 and P48L9, respectively (P < 0.05). Concerning dietary lipid levels, the highest activities of LPL, GOT, SOD, CAT and LZM were observed for larvae fed diets containing 13% lipid (P < 0.05). Regarding to antioxidative factors, same trend was observed for larvae fed diets with 52% protein (P < 0.05). Our results clearly suggested that P52L13 and P48L9 diets could promote the metabolism of protein and lipid, and antioxidative ability of P. fulvidraco larvae in RAS, meanwhile, P52L13 diet is the superior.

Effects of soybean and sunflower meals on the growth, feed utilization, and gene expression in two Canadian strains of juvenile Arctic charr (Salvelinus alpinus)

The effects of graded levels (0–20% total dietary inclusion) of commercial, solvent-extracted soybean meal (SBM) and expeller sunflower meal (SFM) were investigated on growth, nutrient utilization, and pro-inflammatory gene expression in the distal intestine and spleen of two commercial Canadian strains (Strain 1 and Strain 2) of Arctic charr. Five experimental diets with increasing inclusion of SBM or SFM were fed for 84days to two Canadian strains of Arctic charr (initial body weight=9g/fish). Feeding these diets resulted in no differences in growth rate (measured as final weight or thermal-unit growth coefficient, TGC) in the two strains. Increased inclusion level of plant proteins negatively affected FE (P<0.0001) with effects most commonly observed in groups fed SBM-based diets. The effect of the ingredient was significant (P<0.05) on PXR gene expression in the distal intestine; PXR expression was higher with SBM than with SFM. The effect of the inclusion level of plant ingredients was significant (P<0.05) on IL-Iβ gene expression in the spleen. Feed intake, FE, NRE, ERE, whole body crude protein, lipid, gross energy, and organo-somatic indices were significantly (P<0.05) affected by genetic strain examined. Strain 2 exhibited higher FE and carcass crude protein content and lower carcass lipid content. The difference in FE, protein and lipid content for the 2 genetic strains of charr may indicate variations in efficiency for protein and lipid utilization, with a potential protein-sparing effect of dietary lipid noted in Strain 2.

Effects of dietary lipids on the hepatopancreas transcriptome of Chinese mitten crab (Eriocheir sinensis).

Fish oil supplies worldwide have declined sharply over the years. To reduce the use of fish oil in aquaculture, many studies have explored the effects of fish oil substitutions on aquatic animals. To illustrate the effects of dietary lipids on Chinese mitten crab and to improve the use of vegetable oils in the diet of the crabs, 60 male juvenile Chinese mitten crabs were fed one of five diets for 116 days: fish oil (FO), soybean oil (SO), linseed oil (LO), FO + SO (1:1, FSO), and FO + LO (1:1, FLO). Changes in the crab hepatopancreas transcriptome were analyzed using RNA sequencing. There were a total 55,167 unigenes obtained from the transcriptome, of which the expression of 3030 was significantly altered in the FLO vs. FO groups, but the expression of only 412 unigenes was altered in the FSO vs. FO groups. The diets significantly altered the expression of many enzymes involved in lipid metabolism, such as pancreatic lipase, long-chain acyl-CoA synthetases, carnitine palmitoyltransferase I, acetyl-CoA carboxylase, fatty acid synthase, and fatty acyl Δ9-desaturase. The dietary lipids also affected the Toll-like receptor and Janus activated kinase-signal transducers and activators of transcription signaling pathways. Our results indicate that substituting fish oil with vegetable oils in the diet of Chinese mitten crabs might decrease the digestion and absorption of dietary lipids, fatty acids biosynthesis, and immunologic viral defense, and increase β-oxidation by altering the expression of the relevant genes. Our results lay the foundation for further understanding of lipid nutrition in Chinese mitten crab.

Effects of Dietary Lipids on the Growth Performance, Survival, and Digestive Enzymes of Juvenile Cuttlefish, Sepia lycidas

AbstractThis study was conducted to determine the effects of dietary lipids on the growth performance, muscle composition, and enzyme activities of the stomach, intestines, and liver of Sepia lycidas juveniles. Fish oil and soybean lecithin were selected as lipid sources to formulate six experimental diets containing lipid levels of 3.68, 4.15, 6.62, 8.09, 9.56, and 11.03%. The feed efficiency first declined and then rose, with the lowest value obtained in individuals fed the 8.09% lipid content diet; the protein efficiency ratio significantly decreased with an increased lipid level. The highest crude protein content and lowest crude lipid content were simultaneously obtained in individuals fed the 9.56% lipid content diet. The activities of pepsase, trypsin, and intestine lipase initially increased before decreasing. The highest activities of protease, trypsin, and lipase were obtained in individuals fed the 9.56% lipid content diet, while the highest activity of amylase was obtained in individuals fed the 6.62% lipid content diet. Hepatic glutamate pyruvate transaminase and glutamic oxaloacetic transaminase initially increased and then held steady, with the highest activities simultaneously obtained in individuals fed the 9.56% lipid diet. Our results suggest that dietary lipids at a level of 9.56% could be the optimal lipid requirement for S. lycidas to grow and maintain normal metabolism.

Effects of dietary lipid and light source on steatitis in steelhead, Oncorhynchus mykiss

The primary lipid source in feeds used at Pacific salmon (Oncorhynchus spp.) and steelhead (anadromous O. mykiss) conservation hatcheries in California and the Pacific Northwest United States is marine fish oil which is characterized by high levels of long-chain polyunsaturated fatty acids (LC-PUFAs). As these fatty acids are prone to peroxidation, the high marine fish oil content of salmonid feeds is likely a contributing factor in a disease called steatitis which is an ongoing issue at some hatcheries. Dermal lesions associated with steatitis have been observed when affected fish were transferred from enclosed hatchery buildings to outdoor rearing units exposed to sunlight. Therefore, a two-factor study examining possible interactive effects of dietary lipid source and ultraviolet (UV) radiation on growth responses, histology and tissue fatty acid profiles of juvenile steelhead was conducted. For 10weeks, fish were fed diets containing canola oil (CO), fish oil (FO) or oxidized fish oil (OFO) while exposed to fluorescent or UV light. Each treatment was randomly assigned to triplicate groups of 50 fish initially weighing 1.6g/fish. The main effects of lipid and light source on growth responses and survival were not statistically significant, but percent weight gain was significantly affected by interaction of the main effects. Whole body histopathology revealed significantly higher (more severe) steatitis scores in fish fed FO or OFO compared with fish fed CO and in fish exposed to UV light compared with fish exposed to fluorescent light. Whole body lipid concentration and tissue fatty acid profile were significantly affected by lipid and light source but not their interaction. These results suggest reducing dietary LC-PUFAs and minimizing UV light exposure may reduce steatitis in steelhead.

Effect of dietary lipid on growth, expression of canthaxanthin-based coloration, digestive enzymes activities and immunity in blood parrot cichlidAmphilophus citrinellus × Paraneetroplus synspilus

A 42-day experiment was carried out to evaluate the effects of four different lipid containing diets (lipid 74.0, 105.3, 135.0, 168.1 g/kg diet) on growth, digestive enzymes activities, immunology and expression of canthaxanthin-based coloration in parrot cichlid (Amphilophus citrinellus × Paraneetroplus synspilus). Each diet contained canthaxanthin 0.05 g/kg diet. Two hundred and eighty-eight fish were randomly stocked into 12 glass aquaria to form four triplicate groups. Fish were fed one of four diets daily at 20 g/kg of their total body weight. Growth, digestive enzymes activities, immunology and body colour parameters were measured at the end of experiment. Based on the polynomial regression of dietary lipid level and specific growth rate, the dietary lipid level inclusion was calculated as 117.2 g/kg for the highest specific growth rate of these animals. The polynomial regression of skin colour parameters and dietary lipid levels indicated the critical threshold lipid inclusions in diet: 113.7 g/kg for the best expression of lightness, 112.1 g/kg for redness, 127.5 g/kg for yellowness and 125.3 g/kg for chroma of fish's skin. Considering redness, lightness and specific growth rate are most important variables, a diet containing lipid 115.0 g/kg can be recommended for blood parrot cichlid.

Interaction effects of dietary lipid and lysine on growth feed utilization and body composition of juvenile grass carp (Ctenopharyngodon idella)

An 8-week feeding trial was designed to investigate the effects of varying dietary lipid and lysine levels on the growth, feed utilization, and blood characteristics of juvenile grass carp (Ctenopharyngodon idella). Six diets were formulated to contain one of three lysine levels (1.5, 1.7, and 2.0%) and one of two lipid levels (2.4 and 5.4%). Each diet was randomly assigned to triplicate tanks of 30 juvenile fish (initial body weight, 3.00 ± 0.02 g). The results showed that the weight gain, specific growth rate, feed efficiency, protein efficiency ratio, nitrogen retention, and lipid retention were significantly affected by dietary lipid and lysine levels (P 0.05). All growth and feed efficiency indices decreased with an increasing dietary lipid level and significantly improved with lysine supplementation (P < 0.05). The dietary lipid levels significantly influenced the moisture and lipid contents of the whole body and muscle: the lipid content of tissue significantly increased with increasing dietary lipid and was inversely correlated with tissue moisture content (P < 0.05). The hepatosomatic index, intraperitoneal fat index (IPF), and serum cholesterol and triacylglycerol contents were significantly higher in fish that were fed the high-lipid diet (P < 0.05). Fish fed the low-lipid diet showed significantly higher amino acid concentrations compared to those fed the high-lipid diet, and the amino acid content improved with lysine supplementation (P < 0.05). Furthermore, dietary lipid, lysine, and their interaction had significant effects on growth performance, IPF, and tissue lipid content (P < 0.05). The results of the present study suggest a positive effect of dietary lysine supplementation on the growth and feed efficiency, serum lipid metabolism improvement, and reduction of IPF in juvenile grass carp.

Interactive effects of dietary lipids and vitamin E level on performance, blood eicosanoids, and response to mitogen stimulation in broiler chickens of different ages

The effects of the dietary polyunsaturated fatty acids (PUFA) n-6:n-3 ratio and vitamin E (vE) on the levels of pro-inflammatory eicosanoids, the incorporation of docosahexaenoic acid (DHA) and arachidonic acid (AA) into immune tissues, and changes in leukocyte population after phytohemagglutinin (PHA) challenge were investigated in broiler chickens of different ages. One-day-old female broilers (48 per treatment) were fed 4 different wheat-soybean-corn-based diets containing corn oil with a high PUFA n-6:n-3 ratio (HR) or a mixture of linseed and fish oils with a low PUFA n-6:n-3 ratio (LR). Diets contained either 50 mg vE kg−1 of diet (basal vE) or 300 mg vE kg−1 of diet (increased vE). At d 14 and d 34, 8 chickens per treatment were challenged with PHA, and wing web swelling (WWS) was measured. The blood concentration of leukotriene (LTB4), prostaglandin (PGE2), and thromboxane (TBX2) in 17-day-old and 43-day-old chickens was determined. The pattern of AA and DHA incorporation into bursa, spleen, and brain lipids reflected the level of their precursors in the diet. WWS was the highest in chickens fed a LR diet and in 14-day-old chickens (P < 0.01). Leukocyte proportions varied with dietary PUFA n-6:n-3 ratio and with age. The heterophil:lymphocyte ratio was the highest at 6 h post PHA challenge, and was higher in 34-day-old chickens (P < 0.001). TBX2 and PGE2 concentrations were higher in chickens fed HR diet, whereas TBX2 and LTB4 concentrations were lower at high vE level. Lower PGE2 and LTB4, but higher TBX2 concentrations were measured in younger birds (P < 0.001). The results indicated that LR increased the phagocytic cell proportion in the blood; HR promoted the incorporation of AA into the immune tissues, which increased the levels of more pro-inflammatory eicosanoids in the blood; and vE counteracts these effects to some extent. Owing to the immaturity of the immune system, dietary interventions might be promising at the early stage of chicken growth.

Effects of dietary lipids and Clostridium butyricum onchicken volatile flavour compounds

The effect of dietary lipids and Clostridium butyricum supplementation on chicken volatile aroma compounds was investigated. One hundred and ninety two one-day-old broilers were divided into 4 treatment groups in a 2x2 factorial arrangement, and fed four diets with two lipid sources (soybean oil or fish oil) and two levels of C. butyricum (0 or 1´109 CFU/Kg) for a period of 42 days. Dietary lipids and C. butyricum had no effect on broiler performance. The contents of C18:2, C18:3, C20:5n-3, C22:6n-3 and n-3 PUFA were significantly increased in breast muscle by feeding fish oil. Dietary oil had an effect on aroma compounds significantly in breast muscle. Cooked chicken breast muscle from fish oil diet had lower flavor, and the flavor was improved after supplementing with C. butyricum in the diet. The results of this study indicated that fish oil diets could increase the n-3 PUFA content of chicken meat, but lower flavor of cooked chicken. The lowered flavor could be improved by supplementing with C. butyricum in the diet.

Lipid metabolism-related gene expression pattern of Atlantic bluefin tuna (Thunnus thynnus L.) larvae fed on live prey

The present study is the first to evaluate lipid metabolism in first-feeding Atlantic bluefin tuna (ABT; Thunnus thynnus L.) larvae fed different live prey including enriched rotifers Brachionus plicatilis and Acartia sp. copepod nauplii from 2 days after hatch. Understanding the molecular basis of lipid metabolism and regulation in ABT will provide insights to optimize diet formulations for this high-value species new to aquaculture. To this end, we investigated the effect of dietary lipid on whole larvae lipid class and fatty acid compositions and the expression of key genes involved in lipid metabolism in first feeding ABT larvae fed different live prey. Additionally, the expression of lipid metabolism genes in tissues of adult broodstock ABT was evaluated. Growth and survival data indicated that copepods were the best live prey for first feeding ABT and that differences in growth performance and lipid metabolism observed between larvae from different year classes could be a consequence of broodstock nutrition. In addition, expression patterns of lipid metabolic genes observed in ABT larvae in the trials could reflect differences in lipid class and fatty acid compositions of the live prey. The lipid nutritional requirements, including essential fatty acid requirements of larval ABT during the early feeding stages, are unknown, and the present study represents a first step in addressing these highly relevant issues. However, further studies are required to determine nutritional requirements and understand lipid metabolism during development of ABT larvae and to apply the knowledge to the commercial culture of this iconic species.

Dietary low or excess levels of lipids reduced growth performance, and impaired immune function and structure of head kidney, spleen and skin in young grass carp (Ctenopharyngodon idella) under the infection of Aeromonas hydrophila.

Our study explored the effect of dietary lipids on growth and immunity and structure (head kidney, spleen and skin) of young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp with an average initial weight of 261.41±0.53g were fed diets containing six graded levels of lipids at 5.9-80.1g/kg diet for 8 weeks. After that, a challenge trial was conducted by injection of Aeromonas hydrophila over 2 weeks. The results indicated that compared with optimal lipids supplementation, low and excess levels of lipids down-regulated the mRNA levels of antimicrobial peptides, anti-inflammatory cytokines, inhibitor of κBα (IκBα) and ribosomal p70S6 kinase (S6K1), and up-regulated pro-inflammatory cytokines, nuclear factor κB p65 (NF-κB p65), NF-κB c-Rel (not p52), IκB kinase α (IKKα), IKKβ, IKKγ, and eIF4E-binding protein (4EBP) mRNA levels in the head kidney and spleen of young grass carp (P<0.05). Low or excess levels of lipids also increased reactive oxygen species (ROS) production and malondialdehyde (MDA) and protein carbonyl (PC) contents, reduced the activities of antioxidant enzymes (P<0.05), down-regulate the relative mRNA levels of antioxidant enzymes and NF-E2-related factor 2 (Nrf2), and up-regulated the expression levels of Kelch-like ECH-associating protein 1a (Keap1a) and Keap1b in the head kidney and spleen. In addition, low or excess levels of lipids down-regulated the mRNA levels of B-cell lymphoma-2 (Bcl-2) and inhibitor of apoptosis protein (IAP) in the head kidney and spleen, whereas up-regulated the mRNA levels of apoptotic protease activating factor-1 (Apaf-1), caspase 3, 7, 8 and 9 mRNA levels in the head kidney and spleen and Fas ligand (FasL) mRNA levels in the spleen of young grass carp, suggesting that low or excess levels of lipids could decrease the head kidney and spleen immune function, induce oxidative damage and apoptosis and impair antioxidant system of young grass carp. At last, low or excess levels of lipids also impaired the immune function and structure in the skin of young grass carp. Based on the quadratic regression analysis for PWG, skin haemorrhage and lesions morbidity and IgM content, the dietary lipids requirements for young grass carp were estimated to be 43.7, 60.2, 55.0 and 52.1g/kg diet, respectively.

Dietary oils influence ovary and carcass composition and embryonic development of zebrafish

To evaluate the effect of different dietary lipids on zebrafish reproduction, we examined parameters including ovary and carcass composition, oestradiol (E2) levels, eclosion rate and embryonic development. In our study, zebrafish were subjected to a 5-month feeding trial whereby olive (OLV), linseed (LIN), fish (FIS) or corn (CRN) oil were used to compose four isonitrogenous and isoenergetic diets. A positive correlation was found between ovary EPA and whole-body E2 concentration (P = 0.005). The developmental dynamics was affected by dietary lipids and embryos from CRN treatment females; which had higher percentage of ARA in ovary (1.48 ± 0.44%) (P = 0.015), developed faster at 8–9 h postfertilization (hpf) than the ones originated from females receiving other diets (P = 0.0069). This effect was not sustained during later observation periods, suggesting ARA may act as a modulator of developmental dynamics only during initial phases. There was no clear effect of dietary lipid source on ovary protein content (P = 0.304) and eclosion rates at 72 hpf (P = 0.0623). Dietary fatty acids play an important role in reproductive outcome; however, additional studies are necessary to elucidate the mechanisms by which HUFA affect embryonic development.

The Effect of Dietary Lipid on the Growth Performance of Meagre (Argyrosomus regius Asso, 1801).

The aim of the study was to investigate the effects of dietary lipid on the growth and feed utilization of Meagre (Argyrosomus regius Asso, 1801), taking into account their feeding behavior of collecting food from the bottom of the cages. The fish (141.07±0.5g, average weight ± SD; 22.18±0.53 cm, average total length± SD) were fed three isonitrogenous experimental diets (45% crude protein, dry matter) containing 16% (group A), 18% (group B), and 20% (group C) crude lipids for 570 days. The fish were stocked into 9 net cages (16 m diameter; 7 m deep) at a density of 16000 fish per cage with 2 replications. At the end of the experiment fish in the A, B, and C groups reached 1054.59±5.9, 1026.32±4.3, 955.31±2.3 mean live weight (g) and 45.78±1.6, 44.43±1.4, 43.88±1.4 mean total length (cm) respectively. FCR and CF values were 1.99, 2.07, 2.14 and 1.999, 1.131, 1.170 respectively for each group, at the end of the study. VSI, HIS, and GSI values were also calculated. Growth rate in fish from group A (fed the lowest lipid diet) was superior to the other dietary groups. Cross sections of their liver were checked and were found to have less lipidosis.

Effects of dietary protein and lipid levels on growth, feed utilization and body composition in red-tailed catfish juveniles (Hemibagrus wyckioides,Chaux &amp; Fang 1949)

A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red-tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg−1) with three lipid levels (60, 90 and 120 g kg−1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose-somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg−1 protein and 120 g kg−1 lipid diet with P/E ratio of 20.48 mg protein kJ−1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ−1.

Dietary and pharmacological compounds altering intestinal calcium absorption in humans and animals.

The intestine is the only gate for the entry of Ca to the body in humans and mammals. The entrance of Ca occurs via paracellular and intracellular pathways. All steps of the latter pathway are regulated by calcitriol and by other hormones. Dietary and pharmacological compounds also modulate the intestinal Ca absorption process. Among them, dietary Ca and P are known to alter the lipid and protein composition of the brush-border and basolateral membranes and, consequently, Ca transport. Ca intakes are below the requirements recommended by health professionals in most countries, triggering important health problems. Chronic low Ca intake has been related to illness conditions such as osteoporosis, hypertension, renal lithiasis and incidences of human cancer. Carbohydrates, mainly lactose, and prebiotics have been described as positive modulators of intestinal Ca absorption. Apparently, high meat proteins increase intestinal Ca absorption while the effect of dietary lipids remains unclear. Pharmacological compounds such as menadione, dl-butionine-S,R-sulfoximine and ursodeoxycholic acid also modify intestinal Ca absorption as a consequence of altering the redox state of the epithelial cells. The paracellular pathway of intestinal Ca absorption is poorly known and is under present study in some laboratories. Another field that needs to be explored more intensively is the influence of the gene × diet interaction on intestinal Ca absorption. Health professionals should be aware of this knowledge in order to develop nutritional or medical strategies to stimulate the efficiency of intestinal Ca absorption and to prevent diseases.