• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.398-408
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• 2020

The purpose of the present study was to investigate the mechanism of metabolic partitioning between oxidization and esterification of liver fatty acids synthesized and secreted by the liver from egg yolk-fed laboratory rats. Animals were divided into four groups and orally administered egg yolk daily for 30 days: CON (control group, 1.0 g of saline solution), T1 (1.0 g of pork belly oil), T2 (1.0 g of egg yolk), and T3 (1.0 g of pork belly oil and 1.0 g of egg yolk, alternatively each week). The accumulation rate of [¹⁴C]-labelled lipid in liver was lowest in T2 among all treatments (P<0.05). Phospholipid secretion was higher in T2 than other treatments (P<0.05). The triglycerol secretion was highest in T1 and higher in the order of CON, T3, and T2 (P<0.05). Metabolic partitioning rate of phospholipid from total glycerolipid was highest in T2, followed by T3, CON and T1 (P<0.05). The ¹⁴CO₂ production from total glycerolipid was the highest in T2 and showed a high oxidation rate compared to CON, T1, and T3 (P<0.05). Metabolic partitioning of glycerolipid from the liver decreased in triglycerol of T2 compared to CON, T1, and T3, whereas phospholipids of T2 increased (P<0.05).

• Korean Journal of Poultry Science
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• v.39 no.2
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• pp.157-161
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• 2012

The objective of this study was to evaluate the effects of feeding dried Thymus vulgaris powder (TVP) on the layer performance, egg quality and egg yolk fatty acid composition. Two hundred eighty eight, 35 weeks old Brown nicks were allocated in the cage for five TVP (0, 0.25, 0.5, 1.0 and 2.0%) diets with four replicates in each treatment. Each basal diet contained 16.0% CP and 2,800 kcal/kg ME and supplied to layers for 8 weeks. Egg production and egg weight were not statistically different but numerically increased in birds fed 2.0% TVP than other treatments. Egg mass was not consistent depending on the TVP addition levels in diets. Feed intake was significantly lower in TVP addition treatments than the control (p<0.05), however, feed conversion was not significantly differed among control and treatments (p<0.05). Dietary addition of 2.0% TVP showed high values on albumin height, Haugh unit and egg yolk color and they are 7.93, 86.79 and 7.20, respectively (p<0.05). Palmitic and arachidonic acids were remarkably lowered when 2.0% TVP added to basal diets and then fed to birds for 8 weeks, in contrast, significantly higher linolenic acid composition was determined in birds fed 2.0% TVP (p<0.05). As the results, the highest unsaturated fatty composition and UFA/SFA ratio were observed in 2.0% TVP treatment as compared to those of control and other treatments. Therefore, the results indicate that the Thymus vulgaris powder addition to basal diet tended to have positive effects on egg quality and egg yolk fatty acids composition, and the optimum addition of Thymus vulgaris powder may be 2.0%.

• Korean Journal of Poultry Science
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• v.45 no.2
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• pp.109-118
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• 2018

A great progress in genetic selection, nutrition and management practices has contributed to the improved growth rate of broilers and egg production in laying hens. For the increased productivity of modern poultry, a healthy chicken liver needs to cope with the increased metabolic demands. The liver is the major site of de novo fatty acid synthesis; therefore, hepatic lipogenesis is crucial for producing better quality meat and eggs. When de novo lipogenesis exceeds the capacity of lipid metabolism and secretion, large amounts of lipids accumulate in the liver of broilers, leading to a fatty liver. Upon onset of egg-laying in hens, lipids including free fatty acids, triglycerides, and phospholipids are dramatically increased in blood plasma for the synthesis of yolk precursors in oocytes. Productive hens with fatty liver often have hemorrhagic syndrome and sudden death due to the heavy demands of yolk synthesis, which burdens the liver. Understanding the lipid metabolism and hepatic lipid disorders is a key point in the improvement of the growth and production of chickens. This review focuses on the recent studies on lipid metabolism, the hepatic lipid disorders, and the prevention or reduction of fatty liver in poultry.

• Korean Journal of Poultry Science
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• v.26 no.4
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• pp.217-236
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• 1999

Among polyunsaturated fatty acids (PURAs) targeted for manipulation in animal tissues (poultry eggs and meat), omega-3 PUFAs(n-3 PUFAs) are discussed in this review. 3 or 5% dietary menhaden oil (MO) supplemented layer diets was reported to increase docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents in the egg. MO at 1.5% also increased the deposition of up to 180mg total omega-3 fatty acids / yolk. Utilization of 5% ground flax seed (FS) resulted in similar total omega-3 fatty acid (FA) deposition as 1.5% MO. However, the basic feed formulations used in the Canadian feed industry usually include 10 to 20% FS in the egg laying diets. Recently several studies reported that addition of tocopherols in layer diets increased the tocopherol content more in the egg than any other tissue. One of reports said that 3.5% dietary oil with added tocopherols resulted in increasing tocopherol deposition and FA composition of the egg and other tissues. In the poultry meat, redfish meal (RM;4, 8, 12, 15 and 30% of diet) or redfish oil (RO;2.1 or 4.2% of diet) added to the practical corn-wheat-soybean based diets resulted in an increase in omega-3 FA and docosapentaenoic acid (DPA) contents in broiler meat lipids. Linseed oil (LO;1.0, 2.5, and 5.0% of broiler diet) supplemented in broiler diets also resulted in omega-3 FA and the ratio of omega-6 being significantly higher in poultry meat lipid than MO. Concern about fish flavor resulted in research about fish oil (FO) supplementation in broiler diets. Without the use of antioxidants, no more than 1.5% FO should be fed to broilers due to unacceptable orders from the chicken carcasses. One recent research project found that over 50mg/kg of vitamin E was required for maintaining the stability of unsaturated lipids in the meat. In regards to 'fishy'or 'crabby'taint in the eggs and poultry meat, poultry products remained acceptable when dietary fish oils were stabilized with antioxidants.

• Korean Journal of Poultry Science
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• v.31 no.4
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• pp.283-291
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• 2004

Feeding trials were conducted with Euglena strains grown under different media. The effect of supplementation of Euglena on the laying performance, egg quality and fatty acid composition of egg yolk was studied. In experiment I, two hundred eighty 32-wk-old ISA Brown layers were randomly assigned to seven dietary treatments for 4 wks. Each treatment consisted of 4 replications with 10 birds each housed in two birds cages. Control diet was formulated to have $17\%$ CP and 2,750 kcal ME/kg. Euglena gracilis Z. (EG) was added to control diet at the level of 0.25, 0.5, $1.0\%$ and Euglena gracilis Z. bleached and DHA enriched (EGBD; a strain mutated by streptomycin and cultivated in DHA enriched medium) at the level of 0.5, 1.0, $2.0\%$ in the diet. In experiment 2, three hundred 84-wk-old ISA brown layers were randomly assigned to five dietary treatments: T1; Control, T2; T1 + EGBD $0.5\%$, T3; T1 + Euglena gracilis Z. DHA enriched (EGD; cultivated in DHA enriched medium) $0.5\%$, T4; T1 + EGD $1.0\%$, T5; T1 + EGD $2.0\%$. Each treatment had 5 replication of 12 birds each housed in two birds cages. In experiments 1 and 2, Euglena suppplementation did not significantly affect egg production but increased egg weight and feed intake. In experiment 1, EG was more effective in increasing egg yolk color score than EGBD. Egg yolk color of EG $1\%$ treatment showed the highest score. EGBD supplementation increased DHA concentration of egg yolk. EGBD $2\%$ treatment showed the highest DHA and the lowest palmitic and stearic acids concentration in the egg yolk. In experiment 2, EGBD $0.5\%$ treatment showed highest DHA level in egg yolk (P<0.05). It was conducted that EGBD is a single cell protein source rich in DHA, that can be used to produce DHA enriched eggs.

• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.27-37
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• 2024

The poultry plays a crucial role in the animal industry, providing humans with efficient, high-quality animal protein. The rapid growth and short generational intervals of broilers offer significant benefits compared to other economic animals. This growth and increased muscle mass in modern commercial broilers result from advancements in breeding. However, the high productivity of contemporary broilers indicates they are approaching their physiological limits, with excessive fat accumulation becoming a significant industry issue. This not only reduces lean meat yield and feed efficiency but also negatively impacts consumers, especially due to problematic abdominal fat, which consumes more energy than lean meat production. Laying hens, reared for extended periods, maintain high productivity, producing a substantial number of eggs. This productivity in laying hens, akin to broilers, stems from genetic selection and breeding. For egg production, laying hens require physiological support for necessary nutrients. In this context, yolk fat accumulation is a critical physiological process. Lipoproteins, essential in avian lipid metabolism, are vital for yolk and body fat accumulation. Understanding these lipoproteins and their metabolism is key to developing healthier, more productive animals, offering economic benefits to farmers and improved nutritional quality to consumers. This review focuses on the physiological aspects of dietary fat transport, fatty acid biosynthesis in the liver, fat accumulation in the abdomen and muscles, and lipid deposition in egg yolks in chickens. It also highlights recent research trends in the regulation of fat metabolism in poultry.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.1-25
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• 1996

The pathogenesis of atherosclerosis can not be summarized as a single process. Lipid infiltration hypothesis and endothelial injury hypothesis have been proposed and investigated. Recent developments show that there are many points of potential interactions between them and that they can actually be regarded as two phases of a single, unifying hypothesis. Among the many risk factors of atherosclerosis, plasma homocysteine and lipoprotein(a) draw a considerable interest because they are independent indicators of atherogenicity. Triglyceride (TG)-rich lipoproteins (chylomicron and VLDL) are not considered to be atherogenic but they are related to the metabolism of HDL cholesterol and indirectly related to coronary heart disease (CHD). LDL can of itself be atherogenic but the oxidative products of this lipoprotein are more detrimental. HDL cholesterol has been considered to be a favorable cholesterol. The so-called 'causalist view' claims that HDL traps excess cholesterol from cellular membranes and transfers it to TG-rich lipoproteins that are subsequently removed by hepatic receptors. In the so-called 'noncausalist view', HDL does not interfere directly with cholesterol deposition in the arterial wall but instead reflects he metabolism of TG-rich lipoproteins and their conversion to atherogenic remnants. Approximately 70-80% of the human population shows an effective feedback control mechanism in cholesterol homeostasis. Type of dietary fat has a significant effect on the lipoprotein cholesterol metabolism and atherosclerosis. Generally, saturated fatty acids elevate and PUFA lower serum cholesterol, whereas MUFA have no specific effect. EPA and DHA inhibit the synthesis of TG, VLDL and LDL, and may have favourable effects on some of the risk factors. Phospholipids, particularly lecithin, have an antiatherosclerotic effect. Essential phospholipids (EPL) may enhance the formation of polyunsaturated cholesteryl ester (CE) which is less sclerotic and more easily dispersed via enhanced hydrolysis of CE in the arterial wall. Also, neutral fecal steroid elimination may be enhanced and cholesterol absorption reduced following EPL treatment. Antioxidants protect lipoproteins from oxidation, and cells from the injury of toxic, oxidized LDL. The rationale for lowering of serum cholesterol is the strong association between elevation of plasma or serum cholesterol and CHD. Cholesterol-lowing, especially LDL cholesterol, to the target level could be achieved using diet and combination of drug therapy. Information on the link between cholesterol and CHD has decreased egg consumption by 16-25%. Some clinical studies have indicated that dietary cholesterol and egg have a significant hypercholesterolemic effect, while others have indicated no effect. These studies differed in the use of purified cholesterol or cholesterol in eggs, in the range of baseline and challenge cholesterol levels, in the quality and quantity of concomitant dietary fat, in the study population demographics and initial serum cholesterol levels, and clinical settings. Cholesterol content of eggs varies to a certain extent depending on the age, breed and diet of hens. However, egg yolk cholesterol level is very resistant to change because of the particular mechanism involved in yolk formation. Egg yolk contains a factor of factors responsible for accelerated cholesterol metabolism and excretion compared with crystalline cholesterol. One of these factors could be egg lecithin. Egg lecithin may not be as effective as soybean lecithin in lowering serum cholesterol level due probably to the differences of fatty acid composition. However, egg lecithin may have positive effects in hypercholesterolemia by increasing serum HDL level and excretion of fecal cholesterol. The association of serum cholesterol with egg consumption has been widely studied. When the basal or control diet contained little or no cholesterol, consumption of 1 or 2 eggs daily increased the concentration of plasma cholesterol, whereas that of the normolipemic persons on a normal diet was not significantly influenced by consuming 2 to 3 eggs daily. At higher levels of egg consumption, the concentration of HDL tends to increase as well as LDL. There exist hyper-and hypo-responders to dietary (egg) cholesterol. Identifying individuals in both categories would be useful from the point of view of nutrition guidelines. Dietary modification of fatty acid composition has been pursued as a viable method of modifying fat composition of eggs and adding value to eggs. In many cases beneficial effects of PUFA enriched eggs have been demonstrated. Generally, consumption of n-3 fatty acids enriched eggs lowered the concentration of plasma TG and total cholesterol compared to the consumption of regular eggs. Due to the highly oxidative nature of PUFA, stability of this fat is essential. The implication of hepatic lipid accumulation which was observed in hens fed on fish oils should be explored. Nutritional manipulations, such as supplementation with iodine, inhibitors of cholesterol biosynthesis, garlic products, amino acids and high fibre ingredients, have met a limited success in lowering egg cholesterol.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.82-88
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• 2007

Two experiments were conducted to see the effects of lacquer meal (Rhus verniciflua) on layer performance. In Exp. 1, seventy-two Hy-Line brown layers, 46 wk of age were fed 0, 1.5% and 3.0% lacquer added diets for 6 weeks. Diets contained 2,650 kcal/kg ME and 16.50% CP. In Exp. 2, high-energy diets were fed to 72 Hy-line brown layers of 46 wk age for 6 wk. The diets were: control (3,000 kcal/kg ME and 16.50% CP); T1 and T2 contained 1.5 and 3.0% lacquer respectively, in addition to high energy levels. Each treatment had four replicates with 6 birds each in both the experiments. During Exp.1, there was no effect on average daily feed intake, egg production and feed efficiency, however, egg weight was linearly (p=0.0128) decreased with the addition of lacquer in diets. The egg quality parameters measured at bi-weekly intervals did not reveal any particular trend. In Exp 2., high-energy diets have decreased the feed intake and egg production in all groups. However, feeding lacquer at 1.5% increased the egg production by 9% than control. The yolk fat content was increased due to treatments showing quadratic trend (p=0.0683). The liver fat content was decreased by 40-43% than control in lacquer added diets. Except palmitic, oleic and arachidonic acids, some yolk fatty acids showed a linear decreasing trend in lacquer diets. The serum triglycerides and total cholesterol levels were not influenced with lacquer in the diets; however, the serum glucose level was linearly decreased with the addition of lacquer. In conclusion, lacquer meal supplementation significantly affected the performance of layers fed high-energy diets.

• Food Science of Animal Resources
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• v.34 no.1
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• pp.1-6
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• 2014

Pidan and salted duck eggs are of nutritional rich alternative duck egg products which are predominantly consumed in China, Thailand, South Korea and other Chinese migrated countries. Both eggs are rich in proteins, lipids, unsaturated fatty acids and minerals. A Pidan whole egg contains 13.1% of protein, 10.7% of fat, 2.25% of carbohydrate and 2.3% of ash, whereas the salted duck egg contains 14% of protein, 16.6% of fat, 4.1% of carbohydrate and 7.5% of ash. The fresh duck egg contains a range of 9.30-11.80% of protein, 11.40-13.52% of fat, 1.50-1.74% of sugar and 1.10-1.17% of ash. Proteins, lipids, and ash contents are found to be greatly enhanced during the pickling and salting process of pidan and salted duck eggs. However, the alkaline induced aggregation of pidan leads to degradation and subsequent generation of free peptides and amino acids. Very few amino acids are found to be lost during the pickling and storage. However, no such losses of amino acids are reported in salted duck eggs during the salting process of 14 d. Phospholipids and cholesterol contents are lower in pidan oil and salted duck egg yolk oil. Thus, the pidan and salted duck eggs are nutritionally rich alternatives of duck egg products which will benefit the human health during consumption.

• Animal Bioscience
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• v.35 no.9
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• pp.1408-1417
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• 2022

Objective: The objective of this study was to determine whether dietary black soldier fly (Hermetia illucens, HI) larvae oil (HILO) could serve as an alternative fat source to soybean oil (SBO) in laying hen diets. Methods: We randomly assigned 25-week-old Hy-line Brown laying hens (n = 144) to receive (n = 6 hens/group; eight replicates) a control or an experimental diet in which SBO was replaced with 50% (50HILO) or 100% HILO (100HILO). Results: Dietary HILO did not negatively affect body weight or productive performance during the study. The eggs also had similar quality parameters, proximate composition, and cholesterol levels. However, the yolk color index was significantly higher (p<0.01) in the 100HILO than in the other groups. Dietary HILO significantly altered the composition of fatty acids (FAs) in abdominal fat and eggs. Total saturated fatty acids (SFAs) and total polyunsaturated FAs (PUFAs) were significantly increased and decreased in the 50HILO and 100HILO groups, respectively, compared with those in the control group (p<0.001 and p<0.0001, respectively). Specifically, the medium-chain FAs lauric and myristic acids were remarkably increased in the abdominal fat of laying hens fed HILO (p<0.0001), whereas only myristic acid increased in eggs (p<0.0001). Undesirable heavy metal (aluminum, fluorine, arsenic, lead, mercury, and cadmium) concentrations were below permissible limits in eggs. Conclusion: We considered that HILO could be an alternative dietary fat to SBO for laying hens with maintained productive performance and good egg quality.