• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.448-458
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• 2009

It has been well documented from animal and human studies that conjugated linoleic acid (CLA) has numerous beneficial effects on health. In chickens, CLA exerts many effects on performance ranging from egg quality and yolk lipids to meat quality. Although there are several CLA isomers available, not all CLA isomers have the same incorporation rates into egg yolk: cis-9,trans-11 and trans-10,cis-12 CLA isomers are more favorably deposited into egg yolk than other isomers investigated, but of the two isomers, the former has a higher incorporation rate than the latter. CLA alters the amounts and profiles of lipids in plasma, muscles and liver. Furthermore, increased liver weight was reported in chickens fed dietary CLA. As observed in egg yolk, marked reduction in intramuscular lipids as well as increased protein content was observed in different studies, leading to elevation in protein-to-fat ratio. Inconsistency exists for parameters such as body weight gain, feed intake, feed conversion ratio, egg production rate and mortality, depending upon experimental conditions. One setback is that hard-cooked yolks from CLA-consuming hens have higher firmness as refrigeration time and CLA are increased, perhaps owing to alterations in physico-chemistry of yolk. Another is that CLA can be detrimental to hatchability when provided to breeders: eggs from these breeders have impaired development in embryonic and neonatal stages, and have increased and decreased amounts of saturated fatty acids and monounsaturated fatty acids (MUFAs), respectively. Thus, both problems can be fully resolved if dietary sources rich in MUFAs are provided together with CLA. Emerging evidence suggests that CLA exerts a critical impact on stress and immune functions as it can completely nullify some of the adverse effects produced by immune challenges and reduce mortality in a dose-dependent manner. Finally, CLA is a key regulator of genes that may be responsible for lipid metabolism in chickens. CLA down-regulates both expression of the gene encoding stearoyl-CoA desaturase-1 and its protein activity in the chicken liver while up-regulating mRNA of sterol regulatory element-binding protein-l.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.1
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• pp.86-90
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• 2018

Objective: This study was conducted to investigate the effects of dietary detoxified Rhus verniciflua sap (RVS) on production performance, egg quality, lipid fractions of egg yolk, liver and serum, and the profile of cecal microflora in laying hens. Methods: Two hundred 52-week-old Hy-Line Brown layers were randomly divided into 4 groups with 5 replicates per group (2 hens per cage, 5 cages per replicate) and were provided with one of 4 experimental diets containing 0%, 0.05%, 0.1%, or 0.2% RVS, for 6 weeks. Due to unequal intervals of RVS doses, the interactive matrix language procedure of the SAS program was used to correct the contrast coefficients of orthogonal polynomials. Results: There were no differences in feed intake and egg weight among the groups. Egg production increased (linearly and quadratically, p<0.05) with increasing levels of RVS. Eggshell thickness increased (linear, p<0.05) as the level of RVS in diets increased. The levels of blood cholesterol and activities of glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase were not altered by dietary treatments. Increasing level of RVS increased (linear, p<0.05) the populations of cecal lactic acid bacteria. The content of yolk cholesterol decreased (linear, p<0.05) with increasing levels of dietary RVS, although there were no significant differences in each lipid fraction of the liver. Conclusion: This study indicates that dietary RVS could improve laying performance and eggshell quality, and affect cecal lactic acid bacteria in a dose-dependent manner.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.587-594
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• 2013

Egg consumption has been limited to avoid cardiovascular diseases such as atherosclerosis and hyperlipidemia, because the yolk contains high levels of cholesterol. This study was conducted to evaluate the effect of the water-soluble component of egg-yolk on the growth efficiency, immune modulation, and changes in serum lipid levels in BALB/c mice. A total 5 wk old 120 BALB/c male mice were divided into 4 groups and were fed 0, 2, 10, and 20 mg/d water-soluble egg yolk extract (WSEYE) for 5 wk. Water-soluble egg yolk extract (WSEYE) uptake resulted in a significant reduction in daily weight gain and feed efficiency rate (FER). The mouse groups treated with 2 and 20 mg/d WSEYE showed a significant increase in populations of monocytes at the third wk and B-lymphocyte activity at the fifth wk. In addition, WSEYE uptake did not influence serum immunoglobulin E levels. In serum lipid-profile studies, treatment of WSEYE did not alter total cholesterol and low-density lipoprotein levels; however, blood triglyceride levels were significantly diminished in mice treated with 2 mg/d at the third wk (p<0.05), and the level of high-density lipoprotein was significantly increased in the mice group treated with 2 and 10 mg/d WSEYE after 5 wk (p<0.05). Taken together, the data demonstrate the beneficial effects of WSEYE in the diet on immune modulation and serum lipid profiles in mouse models; therefore, this study suggests that ingestion of water-soluble fraction of egg yolk might not be related to the increased risk of heart disease, but can be an excellent candidate for maintaining health.

• Korean journal of food and cookery science
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• v.13 no.2
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• pp.87-91
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• 1997

Egg yolk oil was obtained by roasting and Pressing egg yolks of hen's egg breeding on the open bin system and the cage system, respectively. Lipids in egg yolk oil were extracted with a mixture of chloroform and methanol (2 : 1, V/V), and fractionated into neutral lipid, glycolipid, and phospholipid by silicic aicd column chromatography. Fatty acid composition of each fraction was determined by gas chromatography. The major fatty acids of total lipids and neutral lipids are in sequence of oleic acid, palmitic acid, and linoleic acid. The major fatty acids of the glycolipids are palmitic acid, oleic acid, stearic acid, and lauric acid successively. The major fatty acids of phospholipids are oleic acid, lauric acid, and Palmitic acid consecutively. About the fatty acids composition of egg yolk oil in the open barn system, the contents of saturated fatty acid are lower and the contents of unsaturated fatty acid are higher than that of the case system. The contents of unsaturated fatty acid in egg yolk oil is higher than that of saturated fatty acid in total lipids and nutral lipids. Unsaturated fatty acid/saturated fatty acid of e99 yolk oil in the open barn system is higher than that of the cage system in glycolipids and phospholipids.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.561-566
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• 2015

Effect of the addition of egg yolk lecithin at a concentration of 350 mg/kg on iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation of a water/canola oil emulsion (W/O) during storage at $25^{\circ}C$ was studied based on headspace oxygen consumption and hydroperoxide production. Changes in the phospholipid (PL) composition of the emulsion were determined by high performance liquid chromatography. Headspace oxygen consumption and hydroperoxide content of the emulsion increased with storage time, and addition of egg yolk lecithin did not have any significant effect on these parameters during iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation of the emulsion. PL content of the emulsion decreased during both oxidations, and the degradation rate was higher during autoxidation than during photosensitized oxidation. Phosphatidylcholine content ratio tended to increase during autoxidation. The results suggest that egg yolk lecithin in canola oil emulsion behaves differently during iron-catalyzed autoxidation and chlorophyll-photosensitized oxidation.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.3
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• pp.434-440
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• 2004

The aim of this study was to evaluate effects of modified glucomannan ($Mycosorb^{TM}$) on the antioxidant profile of egg yolk and tissues of newly hatched quail after aurofusarin inclusion in the maternal diet. Fifty-four 45 day-old Japanese quail were divided into three groups and were fed a corn-soya diet balanced in all nutrients ad libitum. The diet of the experimental quail was supplemented with aurofusarin at the level of 26.4 mg/kg feed in the form of Fusarium graminearum culture enriched with aurofusarin or with aurofusarin plus $Mycosorb^{TM}$ at 1 g/kg feed. Eggs obtained after 8 weeks of feeding were analysed and incubated in standard conditions of $37.5^{\circ}C$/55% RH. Samples of quail tissues were collected from newly hatched quail. The main carotenoids, retinol, retinyl esters and malondialdehyde were analysed by HPLC-based methods. Inclusion of aurofusarin in the maternal diet was associated with decreased carotenoid and vitamin A concentrations in egg yolk and liver of newly-hatched quail. Furthermore, lipid peroxidation in quail tissues was enhanced. Inclusion of modified glucomannan ($Mycosorb^{TM}$) in the toxin-contaminated diet provided a significant protective effect against changes in antioxidant composition in the egg yolk and liver. It is suggested that a combination of mycotoxin adsorbents and natural antioxidants could be the next step in counteracting mycotoxins in animal feed.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.243-248
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• 1993

The effect of dietary lipid factors (plant and animal oil, cholesterol and ${\beta}$-sitosterol) on the liver, serum, and egg yolk cholesterol levels of the laying hen was studied. Single Comb White Leghorn laying hens, at 28 weeks of age, were fed two basal diets containing 8.0% soybean oil or 8.0% fish oil, with or without supplemental cholesterol (1.0%), ${\beta}$-sitosterol (2.0%) or combinations of both. Restricting caloric intake resulted in significantly (p<.05) decreased egg production and the total amount of cholesterol excreted via the egg was significantly (p<.05) different among treatment groups. Cholesterol supplementation to the two basal diets resulted in a significant elevation of liver, serum and egg yolk cholesterol levels. The addition of ${\beta}$-sitosterol lowered the cholesterol levels in liver and serum, while increased in the egg yolk (SO + ST, FO + ST). The anticholesterogenic effect of dietary ${\beta}$-sitosterol was not clearly exhibited in this study.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.192-196
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• 1999

The purpose of this experiment was to study the effects of feeding egg yolk prepared from quail fed winged bean oil on plasma and liver cholesterol and fatty acids composition in rats. Eggs were collected from laying quails that had been fed diets containing 5% of either animal tallow, soybean oil, corn oil or winged bean oil. Yolk powders (referred to as winged bean yolk, soybean yolk, etc.) were prepared and fed at the 15% level to weanling female Wistar rats for 28 days. Rats fed winged bean yolk had significantly lower body weight gain than did rats fed soybean yolk or animal tallow yolk. There are no significant effects on plasma total cholesterol, liver cholesterol and triglyceride concentration due to feeding yolk powder containing different oil. However, LDL-cholesterol increased and HDL-cholesterol decreased in rats fed winged bean yolk. Liver lipid of rats fed with winged bean yolk had a higher linoleic but a lower linolenic content than did those fed animal tallow yolk. However, rats fed with winged bean yolk had a lower linoleic content than did rats fed soybean yolk or corn yolk. In conclusion, winged bean yolk seemed to have had an adverse effect on rats.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.3
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• pp.306-312
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• 1986

Demonstration of the highly positive correlation between blood cholestrol levels and heart disease has made consumers wary of the fats in meat, milk and eggs. The egg, as perhaps the single largest common source of cholesterol, has been cited by many members of the medical and scientific world as a food contributing to heart disease. In light of decreasing per capita egg consumption and continuing dietary egg cholesterol controversy, many researchers have focused their efforts on egg nutrition. The results reported, however, are often contradictory. In spite of the disputable scientific evidence, the egg has been labelled (erroneously) as a highly cholesterogenic food. The objective of this presentation is to present a general picture of the problem and discuss our laboratory findings relevant to the problem. An isotope technique was utilized to incorporate $^{14}C$-cholesterol into egg yolk lipoproteins and study the metabolic fate of dietary ovo-cholesterol in rats. Two hundred and fifty micro-curies of 4-$^{14}C$-cholesterol, emulsified in corn oil, were orally administered to five Single Comb White Leghorn laying hens. Eggs were collected, hard-boiled, and the hot dried egg yolk powder (HEY) was prepared. Total radioactivity excreted via feces was determined. The rat groups fed egg yolk powder excreted more than 95% of the ingested ovo-cholesterol, whereas the rat chow group excreted only 47%. No difference was observed between HEY and CEY treatments. Therefore, an unknown lipid factor present in egg folk accelerates cholesterol turnover rate and excretion via feces.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.6
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• pp.831-836
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• 2001

Little information on the cholesterol content and the fatty acid composition of avian species other than chicken is available. This study was conducted to compare the yolk cholesterol content and the fatty acid profiles of some wild birds maintained in captivity on commercial grain-based chicken diets. The concentration of cholesterol/g of yolk as well as the total yolk cholesterol per egg varied among species. Yolk cholesterol concentration, expressed as mg/g of yolk, was highest in chukar, followed by pheasant, guinea fowl and quail, while total yolk cholesterol in an egg was highest in guinea fowl, followed by pheasant, chuckar and quail. An inverse relationship between yolk cholesterol concentration and egg weight was observed among species with an exception of quail. Although major fatty acids of egg yolk were oleic acid, palmitic acid, linoleic acid and stearic acid in all birds, the composition varied among species. Chukar and quail showed higher oleic acid content than pheasant and guinea fowl, while showing lower linoleic acid. Fatty acids of chukar and guinea fowl eggs were more saturated than those of pheasant and quail. Chukar and especially quail had higher monounsaturated fatty acids (MUFA) than pheasant and guinea fowl; in quail egg 51.6% of total fatty acids were MUFA. Polyunsaturated fatty acids (PUFA), essential fatty acids (EFA) and the ratio of PUFA to saturated fatty acid (P/S ratio) were higher in pheasant and guinea fowl than in chukar and quail. Differences in fatty acid profile of triglyceride (TG) among birds were largely similar to those of total lipid. In comparison to TG, phosphatidyl choline (PC) was low in MUFA while high in saturated fatty acids (SFA), PUFA, P/S ratio and EFA. PC was most saturated in guinea fowl egg yolk, followed by chukar, quail and pheasant. PUFA, P/S ratio and EFA in PC were highest in pheasant followed by chukar, guinea fowl and quail. PE was distinguished from PC by its high contents of stearic acid, eicosapentenoic acid (EPA) and docosahexenoic acid (DHA) while low in palmitic, oleic and linoleic acids. In egg yolk of all birds MUFA was significantly lower in PE than in PC except in quail. Compared to other species, quail had a considerably higher content of MUFA in PE at the expense of SFA and PUFA.