Effects of supplemental levels of hesperetin and naringenin on egg quality, serum traits and antioxidant activity of laying hens

Hesperetin and naringenin phytochemicals are naturally occurring flavanoids in citrus fruits. The purpose of this study was to evaluate the effects of supplementing different levels of extracted hesperetin and naringenin on egg quality, serum traits and antioxidant activity in laying hens. Two experiments were conducted, each for 10 weeks, in a completely randomized experiment design. Each had 100 Leghorn laying hens (26 weeks old) randomly assigned into five groups (n = 20) based on dietary categories of hesperetin 0, 0.5, 1, 2, 4 g/kg and naringenin 0, 0.5, 1, 2, 4 g/kg. Experimental results indicated that there was increased (P<0.05) egg production in the 1 g/kg naringenin-supplemented group, but lower (P<0.05) egg production in the hesperetin- and naringenin-supplemented groups given 4 g/kg. Cholesterol content (per gram yolk) and total cholesterol content (per egg) were lower (P<0.05) in the hesperetin- and naringenin-supplemented groups as compared to the control group, and the 2 g/kg hesperetin- and naringenin-supplemented groups showed the most significant difference. Both serum cholesterol and triglyceride concentrations were lower (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups. The SOD and catalase activities, scavenging O₂⁻ and iron-chelating abilities were higher (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups, and the trolox equivalent antioxidant capacity was higher (P<0.05) in the 2 g/kg naringenin-supplemented group. The results confirmed that both hesperetin and naringenin could lower serum and egg yolk cholesterol levels, and improve the antioxidant activities, however the measured variables generally showed significant quadratic responses to increasing amounts of the compounds. The recommended supplementation level of hesperetin and naringenin is 2 g/kg of the basal diet for reduced serum and yolk cholesterols contents and increased antioxidant capacity.     

Ovarian follicular development, lipid peroxidation, antioxidative status and immune response in laying hens fed fish oil-supplemented diets to produce n-3-enriched eggs

The objective of the present study was to research the effect of feeding laying hens fish oil-supplemented diets to produce n-3-enriched eggs on their ovarian follicular development, serum lipid peroxidation, antioxidative status and immune response. A total of 105 white Bovens hens at 24 weeks of age were housed in cages in an open-sided building under a 16 h light : 8 h dark lighting schedule. Birds were randomly divided into five treatments and were fed, ad libitum, diets containing 0% (control), 1.25%, 2.5%, 3.5% or 5.0% fish oil from 24 to 36 weeks of age. Egg production and weight were recorded. By weeks 35 and 36 of age 15 eggs were taken at random from each treatment to determine the yolk lipid profile and cholesterol content. At the end of the experimental period, 10 females from each treatment were randomly chosen, anaesthetised and killed by decapitation. Ovary and oviduct samples were immediately weighted and ovarian follicles were classified. Serum thiobarbituric acid-reactive substance (TBARS), hepatic TBARS and hepatic glutathione peroxidase (GSH-Px) activity were measured. No clear trend was observed concerning egg production and egg yolk cholesterol. As dietary fish oil levels increased, n-3-polyunsaturated fatty acids (n-3 PUFA) increased, whereas n-6 PUFA tended to decrease in yolk lipids. No negative effects were detected in ovary and oviduct weights, expressed in both absolute terms and relative to body weight. The numbers and total weights of large yellow follicles (LYF) in the ovary were not significantly affected by fish oil supplementation. Low levels (1.25% to 2.5%) of fish oil reduced both plasma and hepatic TBARS and enhanced GSH-Px activity. It is also interesting to note that inclusion of 2.5% fish oil in laying hen diets enhanced the antibody titre in laying hens. Therefore, it could be concluded that inclusion of fish oil in laying hen diets at moderate levels increased the n-3 fatty acids content in eggs, improved antioxidative status, enhanced the antibody response and did not have a negative influence on the different reproductive morphology parameters in laying hens.     

Secretion of hepatocyte apoB is inhibited by the flavonoids, naringenin and hesperetin, via reduced activity and expression of ACAT2 and MTP

The citrus flavonoids, naringenin and hesperetin, lower plasma cholesterol in vivo. However, the underlying mechanisms are not fully understood. The ability of these flavonoids to modulate apolipoprotein B (apoB) secretion and cellular cholesterol homeostasis was determined in the human hepatoma cell line, HepG2. apoB accumulation in the media decreased in a dose-dependent manner following 24-h incubations with naringenin (up to 82%, P < 0.00001) or hesperetin (up to 74%, P < 0.002). Decreased apoB secretion was associated with reduced cellular cholesteryl ester mass. Cholesterol esterification was decreased, dose-dependently, up to 84% (P < 0.0001) at flavonoid concentrations of 200 microM. Neither flavonoid demonstrated selective inhibition of either form of acyl CoA:cholesterol acyltransferase (ACAT) as determined using CHO cells stably transfected with either ACAT1 or ACAT2. However, in HepG2 cells, ACAT2 mRNA was selectively decreased (- 50%, P < 0.001) by both flavonoids, whereas ACAT1 mRNA was unaffected. In addition, naringenin and hesperetin decreased both the activity (- 20% to - 40%, P < 0.00004) and expression (- 30% to - 40%, P < 0.02) of microsomal triglyceride transfer protein (MTP). Both flavonoids caused a 5- to 7-fold increase (P < 0.02) in low density lipoprotein (LDL) receptor mRNA, which resulted in a 1.5- to 2-fold increase in uptake and degradation of (125)I-LDL. We conclude that both naringenin and hesperetin decrease the availability of lipids for assembly of apoB-containing lipoproteins, an effect mediated by 1) reduced activities of ACAT1 and ACAT2, 2) a selective decrease in ACAT2 expression, and 3) reduced MTP activity. Together with an enhanced expression of the LDL receptor, these mechanisms may explain the hypocholesterolemic properties of the citrus flavonoids.     

Effects of the usage of dried brewing yeast in the diets on the performance, egg traits and blood parameters in quails

This experiment was carried out to determine the effects of the usage of dried brewing yeast in quail diets on laying performance, egg traits and blood parameters. A total of 240 Japanese quails (Coturnix coturnix japonica) aged 10 weeks were randomly allocated into one control group and three treatment groups. Each group was divided into five replicates as subgroups, comprising 12 quails each. Dried brewing yeast (Saccharomyces cerevisiae) was used at the levels of 1.5%, 3.0% and 4.5% in the diets of the first, second and third treatment groups, respectively. Soyabean meal was replaced with dried brewing yeast. The diets were formulated to be isocaloric and isonitrogenous. The experimental period lasted 18 weeks. Dietary treatments did not significantly affect body weight, daily feed intake, daily protein intake, egg production, egg weight, feed efficiency, mortality, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, the percentages of egg shell, albumen and yolk, excreta moisture and small intestinal pH. Inclusion of 3% and 4.5% dried brewing yeast in diets reduced egg yolk cholesterol concentration as mg per yolk and mg per g yolk (P < 0.01). Blood serum cholesterol of groups fed diets with dried brewing yeast was significantly lower (P < 0.01) than that of the control group. Feeding diets containing 3.0% and 4.5% dried brewing yeast resulted in significant increases (P < 0.01) in blood serum levels of total protein, alanine aminotransferase at the end of the experiment. Blood serum levels of uric acid, triglyceride, aspartate aminotransferase and alkaline phosphatase were not affected by dietary dried brewing yeast. It is concluded that dried brewing yeast can be used up to 4.5% in the diets of laying quails without adverse effects on the measured parameters.     

Effect of alfalfa meal in diets of laying quails on performance, egg quality and some serum parameters

This study was conducted to investigate the effects of increasing levels of alfalfa meal in the diet of laying quails on egg production, feed consumption, feed efficiency, egg quality, egg yolk cholesterol and selected serum parameters. In this study, 192, 10-week old quails (Coturnix coturnix japonica) were evenly distributed to four groups with four replicates of 12 quails each. The control group was fed a basal diet containing 0% alfalfa meal and the remaining groups received 3, 6 or 9% alfalfa meal for 12 weeks. Live weight, feed consumption, and egg production were recorded and feed efficiency were calculated. Eggs were examined for interior and exterior quality and egg yolk cholesterol content. At the end of the experiment, blood samples were collected and sera were analysed for serum Ca, inorganic P (P(i)), Mg, triglycerides and total cholesterol. Any level of alfalfa meal had no effect on live weight, egg production, feed consumption, feed efficiency, egg weight, and egg yolk index. Six percent and 9% alfalfa meal increased specific gravity of whole egg and eggshell thickness as well as serum P(i) levels. Nine percent alfalfa meal reduced serum triglycerides, total cholesterol levels and egg yolk cholesterol content. The results of this experiment indicated that addition of 9% alfalfa meal into the laying quail diet may improve eggshell quality and reduced serum triglycerides and serum and egg yolk cholesterol without any adverse effect on performance.     

Effects of dietary conjugated linoleic acids on lipid metabolism and antioxidant capacity in laying hens

To examine the effects of dietary conjugated linoleic acids (CLA) on lipid metabolism and antioxidant capacity in laying hens, Hy-Line Brown layers (n = 384, 52 weeks old) were randomly allocated to one of four dietary treatments. Each treatment had six replicates of 16 hens each. All birds were assigned to a corn-soybean meal-based diet containing a mixture of CLA at 0%, 1%, 2% or 4% for six weeks. With increasing dietary CLA, egg weight and feed intake decreased, and yolk colour was darkened. Feed efficiency was improved at 1% and 2% dietary CLA. Serum triglyceride concentration was significantly reduced by CLA in a dose dependent manner. A linear decrease in total cholesterol and low-density lipoprotein cholesterol, and an increase in high-density lipoprotein cholesterol levels were observed after CLA supplementation. With increasing dietary CLA, the deposition of two major isomers of CLA (c9, t11; t10, c12) in yolk lipids increased linearly, the proportion of saturated fatty acids increased and monounsaturated fatty acids decreased significantly. The proportion of polyunsaturated fatty acids was highest at 1% CLA. Compared to the control, CLA supplementation significantly increased the activities of superoxide dismutase and glutathione peroxidase, inhibited hydroxyl radicals and superoxide anion production, and decreased the malonaldehyde concentrations in both serum and liver. The results demonstrated that dietary CLA meliorated serum lipid profiles and enhanced the antioxidant capacity of laying hens.     

Effect of Alfalfa Meal in diets of laying quails on performance,egg quality and some serum parameters

This study was conducted to investigate the effects of increasing levels of alfalfa meal in the diet of laying quails on egg production, feed consumption, feed efficiency, egg quality, egg yolk cholesterol and selected serum parameters. In this study, 192, 10-week old quails (Coturnix coturnix japonica) were evenly distributed to four groups with four replicates of 12 quails each. The control group was fed a basal diet containing 0% alfalfa meal and the remaining groups received 3, 6 or 9% alfalfa meal for 12 weeks. Live weight, feed consumption, and egg production were recorded and feed efficiency were calculated. Eggs were examined for interior and exterior quality and egg yolk cholesterol content. At the end of the experiment, blood samples were collected and sera were analysed for serum Ca, inorganic P (P_i), Mg, triglycerides and total cholesterol. Any level of alfalfa meal had no effect on live weight, egg production, feed consumption, feed efficiency, egg weight, and egg yolk index. Six percent and 9% alfalfa meal increased specific gravity of whole egg and eggshell thickness as well as serum P_i levels. Nine percent alfalfa meal reduced serum triglycerides, total cholesterol levels and egg yolk cholesterol content. The results of this experiment indicated that addition of 9% alfalfa meal into the laying quail diet may improve eggshell quality and reduced serum triglycerides and serum and egg yolk cholesterol without any adverse effect on performance.     

The effect of replacing soya bean oil with glycerol in diets on performance,egg quality and egg fatty acid composition in laying hens

The objective of this experiment was to replace soya bean oil with glycerol in laying hen diets and assess the change’s effect on performance, parameters of egg quality and the egg fatty acid profile. A total of 60 44-week-old Hy-Line W36 laying hens were distributed according to a completely randomised experimental design into four treatments consisting of glycerol substitutions for soya bean oil dietary at varying inclusion levels (0%, 25%, 50% and 75%), with five replicates of three birds each. Dietary treatments had no significant effect on BW change, egg production, feed intake, feed conversion ratio, egg weight and egg mass of laying hens. The inclusion of glycerol in the diet of laying hens had no significant effect on egg specific gravity, eggshell breaking strength, eggshell weight, eggshell thickness, egg shape index, albumen index, yolk index, haugh unit, albumen pH, yolk pH and egg yolk colour values. The inclusion of glycerol in the diet of laying hens had no significant effect on palmitic, palmitoleic, stearic, oleic and linolenic acid contents of the egg yolk. The linoleic acid and polyunsaturated fatty acid contents of the egg yolk significantly decreased with the higher levels of dietary glycerol supplementation (P<0.05). The results of this study show that it is possible to replace 75% of soya bean oil (4.5% in diet) with glycerol.     

Untersuchungen über die Wirkung von Vitamin B12 und behandeltem Sojaschrot bei der Mast von Küken

To examine the effects of dietary conjugated linoleic acids (CLA) on lipid metabolism and antioxidant capacity in laying hens, Hy-Line Brown layers (n = 384, 52 weeks old) were randomly allocated to one of four dietary treatments. Each treatment had six replicates of 16 hens each. All birds were assigned to acorn-soybean meal-based diet containing a mixture of CLA at 0%, 1%, 2% or 4% for six weeks. With increasing dietary CLA, egg weight and feed intake decreased, and yolk colour was darkened. Feed efficiency was improved at 1% and 2% dietary CLA. Serum triglyceride concentration was significantly reduced by CLA in a dose dependent manner. A linear decrease in total cholesterol and low-density lipoprotein cholesterol, and an increase in high-density lipoprotein cholesterol levels were observed after CLA supplementation. With increasing dietary CLA, the deposition of two major isomers of CLA (c9, t11; t10, c12) in yolk lipids increased linearly, the proportion of saturated fatty acids increased and monounsaturated fatty acids decreased significantly. The proportion of polyunsaturated fatty acids was highest at 1% CLA. Compared to the control, CLA supplementation significantly increased the activities of superoxide dismutase and glutathione peroxidase, inhibited hydroxyl radicals and superoxide anion production, and decreased the malonaldehyde concentrations in both serum and liver. The results demonstrated that dietary CLA meliorated serum lipid profiles and enhanced the antioxidant capacity of laying hens.     

Effect of dietary supplementation of Ligustrum lucidum on performance,egg quality and blood biochemical parameters of Hy-Line Brown hens during the late laying period

The fruit of Ligustrum lucidum (FLL, Nuzhenzi in Chinese) is an important traditional medicine, and have attracted significant research attention because of their various biological activities. However, there are few research reports available on the use of FLL as a feed additive in livestock nutrition, particularly in layers. This study was conducted to determine the effects of supplementation of the diet of laying hens with FLL on laying performance, egg quality and blood metabolites. A total of 360 72-week-old hens were allocated to three dietary treatments (eight replications of 15 hens/treatment group) and were fed either a control diet or a diet supplemented with an inclusion level of 0.25% or 0.50% of FLL powder in the final feed, until 78 weeks of age. Hens were housed in a three-tier cage system. Feed and water were provided ad libitum. Blood samples and eggs were collected at the end of the experiment. The results showed that dietary supplementation with FLL did not affect egg weight, feed conversion ratio, eggshell thickness, albumen height, egg yolk color, eggshell breaking strength or egg shape index. However, FLL supplementation significantly decreased (P<0.001) mortality, cracked-egg rate and blood serum levels of cholesterol, low-density lipoprotein cholesterol, triglycerides and alanine aminotransferase, and increased (P<0.001) blood serum levels of high-density lipoprotein cholesterol. No differences in serum levels of total protein, albumin, glucose, calcium, aspartate aminotransferase or alkaline phosphatase were observed in hens fed FLL compared with the control group. It can be concluded that FLL, at a supplementation level of 0.25% final feed, can be used as an effective feed additive to improve the performance of laying hens during the late laying period.     

Effects of faba beans with different concentrations of vicine and convicine on egg production,egg quality and red blood cells in laying hens

The faba bean (Vicia faba L.) is a potential source of proteins for poultry, mainly for laying hens whose protein requirements are lower than those of other birds such as growing broilers and turkeys. However, this feedstuff contains anti-nutritional factors, that is, vicine (V) and convicine (C) that are already known to reduce laying hen performance. The aim of the experiment reported here was to evaluate the effects of a wide range of dietary V and C concentrations in laying hens. Two trials were performed with laying hens fed diets including 20% or 25% of faba bean genotypes highly contrasting in V+C content. In Trial 1, faba beans from two tannin-containing cultivars, but with high or low V+C content were dehulled in order to eliminate the tannin effect. In addition to the contrasting levels of V+C in the two cultivars, two intermediate levels of V+C were obtained by mixing the two cultivars (70/30 and 30/70). In Trial 2, two isogenic zero-tannin faba bean genotypes with high or low V+C content were used. In both trials, a classical corn–soybean diet was also offered to control hens. Each experimental diet was given to 48 laying hens for 140 (Trial 1) or 89 (Trial 2) days. Laying performance and egg quality were measured. The redox sensitivity of red blood cells (RBCs) was assessed by measuring hemolysis and reduced glutathione (GSH) concentration in these cells. Egg weight was significantly reduced by the diets containing the highest concentrations of V+C (P<0.0001) in Trial 1 and slightly reduced (P<0.10) in Trial 2, but only weak linear relationships between egg weight and dietary V+C concentration were established. No negative effect of V+C level was observed for egg quality parameters. In contrast, certain parameters (i.e. Haugh units, yolk color) were improved by feeding low V+C diets (P<0.05). Hemolysis of RBCs was higher in hens fed high V+C diets. A decrease in GSH concentration in RBCs of hens fed the highest levels of V+C was observed. Faba bean genotypes with low concentrations of V+C can therefore be used in laying hen diets up to 25% without any detrimental effects on performance levels or egg characteristics, without any risk of hemolysis of RBCs.     

The impact of incorporation of n-3 fatty acids into eggs on ovarian follicular development, immune response, antioxidative status and tibial bone characteristics in aged laying hens

The objectives of this study were to investigate the effects of different dietary sources of unsaturated fatty acids (fish oil (FO) and/or linseed oil (LO)) on laying performance, egg yolk fatty acid composition, ovarian follicular development, antioxidative properties, immune response and tibial bone characteristics in aged laying hens. A total of 100 Hisex Brown hens at 56 weeks of age were housed individually in laying cages in an open-sided building under a 16 h light:8 h dark lighting schedule. Hens were randomly divided into four experimental treatments (n=25 each). Birds were fed ad libitum diets containing 2.5% vegetable oil (C, control), 2.5% FO, 2.5% LO and a mixture of 1.25% LO+1.25% FO (LO+FO) from 56 to 68 weeks of age. Egg production, egg quality characteristics and yolk lipid profile were analyzed. At 68 weeks of age, ovarian follicles were classified and tibial bone characteristics were determined. Serum thiobarbituric acid reactive substance (TBARS), glutathione peroxidase (GSH-Px) activity and total antioxidant capacity were measured. Incorporation of n-3 polyunsaturated fatty acids (n-3PUFA) into the egg yolks has been successful by using dietary FO and/or LO. There were no significant effects of treatments on hen-day egg production, feed intake, egg weight, egg shape index, albumen height, Haugh units and yolk height. However, dietary FO and/or LO supplementation had a significantly positive effect on eggshell percentage, eggshell thickness and yolk color. At 68 weeks of age, there was no significant difference among dietary treatments for tibial bone measurements. Also, no negative effects were detected in ovarian follicular development and weights of the ovary and oviduct, expressed in both absolute terms and relative to body weight. Dietary 2.5% LO, 2.5% FO and a mixture of 1.25% FO+1.25% LO enhanced GSH-Px activity, total antioxidant capacity and antibody titers significantly in comparison with control. It could be concluded that inclusion of mixed sources of n-3PUFA in diets at moderate levels (2.5%) increased the n-3PUFA content and decreased the n-6/n-3 ratio content in the yolk, improved the antioxidative status, reduced lipid peroxidation, enhanced the antibody response and did not have any negative influence on ovarian follicular development and tibial bone characteristics in aged laying hens.     

Dietary Coenzyme Q10 Suppressed Hepatic Hydroxymethylglutaryl-CoA Reductase Activity in Laying Hens

The effects of dietary coenzyme Q10 (CoQ10) on cholesterol metabolism in laying hens were investigated. Dietary CoQ10 significantly reduced egg yolk cholesterol content and suppressed hepatic hydroxymethylglutaryl-CoA reductase (HMGR) activity. It is therefore likely that CoQ10 acts as an HMGR inhibitor in the livers of laying hens, which in turn results in a reduction in egg-yolk cholesterol.     

Detection of Transgenic and Endogenous Plant DNA Fragments and Proteins in the Digesta,Blood, Tissues,and Eggs of Laying Hens Fed with Phytase Transgenic Corn

The trials were conducted to assess the effects of long-term feeding with phytase transgenic corn (PTC) to hens on laying performance and egg quality, and investigate the fate of transgenic DNA and protein in digesta, blood, tissues, and eggs. Fifty-week old laying hens (n = 144) were fed with a diet containing 62.4% PTC or non-transgenic isogenic control corn (CC) for 16 weeks. We observed that feeding PTC to laying hens had no adverse effect on laying performance or egg quality (P>0.05) except on yolk color (P<0.05). Transgenic phyA2 gene and protein were rapidly degraded in the digestive tract and were not detected in blood, heart, liver, spleen, kidney, breast muscle, and eggs of laying hens fed with diet containing PTC. It was concluded that performance of hens fed diets containing PTC, as measured by egg production and egg quality, was similar to that of hens fed diets formulated with CC. There was no evidence of phyA2 gene or protein translocation to the blood, tissues, and eggs of laying hens.     

Effect of gamma-linolenic acid on lipid metabolism in laying hens.

1. Single comb white leghorn laying hens were given diets with additional mould, Mucus circineloides, containing gamma-linolenic acid (GLA) at levels of 0, 2.59 and 5.06 g GLA/kg diet ad lib. for 2 weeks and serum lipid contents were determined in experiment 1. 2. Serum low density lipoprotein and chylomicron levels were significantly reduced with the increase of dietary GLA levels. Serum triglyceride and cholesterol tended to be lowered by dietary GLA, but not significantly different. 3. Effects of mould GLA and extracted oil GLA on the egg yolk cholesterol concentration and fatty acid composition were compared in experiment 2. Both mould GLA and extracted oil GLA diets containing 5.32 and 4.71 g GLA/kg diet were given ad lib. for 2 weeks. 4. Yolk cholesterol content was not affected by dietary GLA sources. Content of GLA in the yolk was not altered, although that of arachidonic acid was enhanced by dietary GLA supplementation, particularly by the extracted oil GLA. 5. It is suggested that GLA is rapidly metabolized to arachidonic acid in the body and incorporated into the yolk.     

Potential use of seaweeds in the laying hen ration to improve the quality of n-3 fatty acid enriched eggs

An association between dietary fish oil and decreased yolk weight and reduced sensory quality of eggs has been reported when eggs are enriched with n-3 FA from fish oil. Seaweeds are an important source of compounds that seem to increase egg weight when included in the laying hen diet. The objectives of this study were to determine the influence of the dietary seaweeds Macrocystis pyrifera, Sargassum sinicola and Enteromorpha sp. on the physical quality, lipid composition and consumer acceptability of n-3 FA enriched eggs. One-hundred and forty-four 35-week-old Leghorn hens were randomly distributed in four treatments that consisted of the inclusion of 2% of sardine oil (SO) and 10% of each marine alga (MA) in laying hens' diets; a control diet (C) was also prepared. The study lasted 8 weeks and egg physical quality, egg lipids and sensory attributes were evaluated. The results showed that incorporation of 10% M. pyrifera in the diets is an effective way of increasing the n-3 FA content, the albumen height and yolk color, but not the egg weight, when these are enriched with n-3 FA from fish oil. The egg flavor was also not affected.     

Flaxseed and dried tomato waste used together in laying hens diet

The aim of this study was to investigate the effects of simultaneous supplementation of laying hens with dietary sources of n-3 polyunsaturated fatty acids (PUFA) and carotenoids on egg quality, fatty acids and carotenoid profile of the egg yolk and on feed and yolk lipid peroxidation. A 6-week experiment was carried out with 53-week old laying hens (96 Tetra SL) assigned to a control and three treatment groups supplemented with 5% flaxseeds and different levels of dried tomato waste (DTW, 2.5%, 5.0% and 10.0%). Hens from the groups supplemented with 5% and 7.5% DTW had a significantly lower average daily feed intake and laying percentage as compared to the control. Increased doses of dietary DTW enhanced yolk Roche colour score in direct correlation with the enrichment of egg yolk in carotenoids but decreased their transfer efficiency from feed to egg. After 4 weeks, egg yolk from hens fed with 5% flaxseeds and 7.5% DTW had increased lutein and zeaxanthin levels (by 29% and 24%, respectively) and the colour score was 3.5 fold higher compared to the control group. As a result of the dietary supplementation with flaxseed, the n-3 fatty acid content was 3.1–3.7-fold higher in egg yolk compared with the control and the n-6/n-3 ratio decreased from 18.3 (control) to 4.1–5.4 in supplemented diets. Dietary supplementation with 5% DTW effectively prevented lipid oxidation of eggs enriched with n-3 PUFA, but the increase in DTW content depressed the absorption and deposition of n-3 PUFA in egg yolk.     

Effect of Ligustrum lucidum and Schisandra chinensis on the egg production, antioxidant status and immunity of laying hens during heat stress

The experiment was conducted to evaluate the effect of two plants belonging to Chinese herbal medicines, Ligustrum lucidum (LL) and Schisandra chinensis (SC), on the laying performance, antioxidant status and immunity of hens during heat stress. The results showed that diets supplement with 1% of either LL or SC had beneficial effects on egg production and FCR of hens during heat stress (p < 0.05), compared with the control group. Either LL or SC significantly reduced malondialdehyde (MDA) concentration of heart, liver, sera and egg yolk. In addition, glutathione reductase (GR) activity of tissues and sera of the birds was significantly elevated by supplementation LL or SC. Furthermore, LL or SC supplementation significantly elevated lymphoblastogenese of the birds and the antibody values against Newcastle disease virus (NDV). The results suggest that diets supplement with 1% of either LL or SC may enhance egg production, immune function, and antioxidant status of hens during heat stress.     

Rapid modulation of the n-3 docosahexaenoic acid levels in the brain and retina of the newly hatched chick

The newly hatched chick obtains its fatty acids almost completely from the lipids of the egg yolk as these are transferred to the developing embryo during its 21-day period of incubation. Since the diet of the laying hen greatly influences the fatty acid composition of the egg lipids, and presumably also the fatty acid composition of the resulting chick, we tested how quickly and to what extent varying the amount of n-3 fatty acids in the diet of the hen would modulate the level of n-3 fatty acids in the brain and retina of the newly hatched chick. White Leghorn hens were fed commercial or semi-purified diets supplemented with 10% fish oil, linseed oil, soy oil, or safflower oil. Eggs, together with the brain, retina, and serum of newly hatched chicks, were then analyzed for fatty acid composition. The fatty acids of egg yolk responded quickly to the hen's diet with most of the change occurring by 4 weeks. There was a linear relationship between the linolenic acid content of the diets and levels of this fatty acid in egg yolk and chick serum. In chicks from hens fed the fish oil diet, the total n-3 fatty acids, including 22:6(n-3), were elevated twofold in the brain and retina and sevenfold in serum relative to commercial diet controls. The safflower oil diet led to a very low n-3 fatty acid content in egg yolks and only 25% of the control n-3 fatty acid content in the brain and retina of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Does Dietary vitamin E or C Decrease Egg Yolk Cholesterol?

An experiment was conducted to determine the effect of dietary vitamin E and C on serum metabolites, yolk cholesterol, egg quality, and performance of layer hens. One hundred sixty-eight commercial Hy-Line W-36 layer hens were randomly divided into seven groups and six replicates with four hens in each. Dietary treatments were introduced after the pre-experimental period (10 days) to adjust egg production. Treatments were levels of vitamin E or C (100, 200, and 400 mg/kg diet) supplementation to the basal diet for 4 weeks, whereas the control group received no supplementation. Egg production, egg weight, and feed consumption were recorded during the study. Shell thickness, Haugh unit score, yolk color, yolk weight, yolk cholesterol, and blood parameters were measured at the end of experiment. There was no significant effect of dietary vitamin E or C on hen performance. Egg yolk cholesterol concentrations decreased linearly by antioxidant vitamin supplementation (P?<?0.01). Egg yolk cholesterol reduction did not have any negative effect on egg production rate. Antioxidants, especially vitamin C, increased serum glucose concentration (P?<?0.05). Serum total cholesterol content did not change by vitamin supplementation but cholesterol in high-density lipoprotein (HDL-C) decreased and cholesterol in low-density lipoprotein (LDL-C) increased (P?<?0.05), as dietary vitamin E or C supplementation increased in diets. These results are in conflict with the previous hypothesis that antioxidants have a role in LDL-C removal from the blood or increasing HDL-C. Vitamin E was more effective than vitamin C in this case and if these results are confirmed by further studies, they may result to revision in researchers’ point of view about antioxidant especially in human medicine.