Effects of dietary conjugated linoleic acid on the productivity of laying hens and egg quality during refrigerated storage

Dietary flaxseed cake influences on performance, quality, and sensory attributes of eggs, serum, and egg trace minerals of laying hens

Nowadays, there is a global shortage in feed supply for animal nutrition; however, there are a considerable amount of agro-industrial co- and by-products that may offer a reasonable solution. Flaxseed cake (FSC) is a by-product of flaxseed for oil extraction rich in n-3 α-linolenic acid (ALA). Thus, the dietary inclusion of FSC on laying performance, egg quality, and serum and egg trace elements (Se, Zn, and Fe) was evaluated using Hisex White hens. The hens were distributed to three equal experimental treatments and provided diets including 0%, 5%, or 10% FSC from 48 to 58 weeks of age. Findings clarified that up to 10% FSC in the laying hen diet had no detrimental effect on laying rate, egg mass, and feed utilization. It was found that FSC resulted in a valuable source of protein, energy, macro- (Ca and P), micro- (Se, Zn and Fe) elements, and essential amino acids, with arginine being the highest. Dietary FSC did not negatively influence the egg quality traits, as well as egg sensory attributes. Including 5% or 10% FSC in diet did not significantly affect serum total protein and renal function in terms of creatinine, uric acid, and uric acid-to-creatinine ratio. Different FSC levels did not influence the chemical composition of eggs and trace elements in serum and eggs. It could be concluded that FSC is a valuable feedstuff that can provide a good source of energy, protein, amino acids, and macro- and micro-elements for hens' nutrition. The inclusion of up to 10% of FSC in hens diet did not adversely influence egg laying performance, egg quality of both fresh and stored eggs, sensory attributes, and nutritional composition, as well as Se, Zn, and Fe in serum and eggs due to balanced nutrient profile of FSC.

Effects of Dietary Thraustochytrid schizochytrium sp. and Other Omega-3 Sources on Growth Performance, Carcass Characteristics, and Meat Quality of Broilers

Simple Summary

Thraustochytrid schizochytrium is one of the promising microalgae for omega-3 production. We evaluated the possibility of schizochytrium as omega-3 source comparing with other omega-3 sources that have been used before. The main results were the increased levels of DHA in the thigh meat of broilers fed SP, while EPA and DHA were on the rise in the meat of broilers fed SO, and ALA was increased in the meat of broilers fed FO. The ω-6/ω-3 ratio of the thigh meat improved in all treatments, approaching the guideline levels without adverse effects on the productive performance, carcass traits, and thigh meat quality. Hence, our results suggest that salmon oil, flaxseed oil, and schizochytrium could be used as omega-3 fatty acids sources to improve the omega-3 level and ω-6/ω-3 balance in broiler thigh meat and to allow consumers to easily enhance their intake of these vital nutrients for health benefits.

Abstract

Background: Looking for alternative omega-3 sources in broiler nutrition, microalgae began to get attention. We suspected that schizochytrium might play a similar role as other omega-3 sources that have been used before. Methods: 20 g/kg schizochytrium powder (SP), salmon oil (SO), and flaxseed oil (FO) in each of the three treatment groups were supplemented in the basal diet (CON), and productive performance, carcass traits, and thigh meat quality of broilers were evaluated. Results: There was a significantly higher weight gain in the SP treatment compared to the other groups, but no difference was found in feed intake and feed conversion ratio. Thiobarbituric acid reactive substance values increased during storage in all the treatments but were significantly lower for SP than for SO and FO after 7 days of storage. Among the ω-3 fatty acids (FAs), α-linolenic acid increased the most in the FO treatment, eicosapentaenoic acid increased the most in the SO treatment, and docosahexaenoic acid increased the most in the SP treatment in thigh meat, reflecting the FA composition of the lipid source diets. Conclusions: We suggested that all the dietary ω-3 FA sources could improve the FA composition of chicken meat and our results indicated the possibility to supplement broiler diets with 2% level of SP, SO, and FO as ω-3 FA sources to produce meat with a good nutritional quality for consumer’s health benefits.

Effect of Escherichia coli lipopolysaccharide challenge on eggshell, tibia, and keel bone attributes in ISA brown hens exposed to dietary n-3 fatty acids prior to onset of lay

The impact of Escherichia coli lipopolysaccharide (LPS) challenge on eggshell, tibia, and keel bone characteristics in ISA brown hens derived from breeders and pullets fed omega-3 polyunsaturated fatty acids (n-3 PUFA) was examined. The breeders were fed the following diets: 1) Control (CON); 2) CON + 1% microalgae as the source of docosahexaenoic acid (DHA); and 3) CON + 2.6% of a co-extruded mixture of full-fat flaxseed and pulses as a source of α-linolenic acid (ALA). During the pullet phase, offspring from breeders fed CON were fed CON or supplemented diets, and offspring from supplemented diets either continued with respective n-3 PUFA diets or CON. At 18 weeks of age (WOA), pullets were fed a common layer diet to 42 WOA. A total of 5 birds were selected based on the average body weight (BW) of each treatment and moved to an individual cage at 41 WOA. Three days before the end of 42 WOA, all the birds were weighed and subcutaneously injected with either saline or 4 mg LPS/kg BW. Eggs were recorded, labeled, and kept for egg quality analyses. At 42 WOA, birds were necropsied for tibia and keel bone samples. Administration of LPS reduced eggshell breaking strength, eggshell weight, tibia, and keel bone ash content (P < 0.05). Specifically, LPS challenged hens had 14.9, 11.1, 9.2, and 11.6% lower eggshell breaking strength, eggshell weight, keel, and tibia ash content, respectively relative to unchallenged hens. Hens from breeders and pullets fed n-3 PUFA had similar (P > 0.05) eggshell, tibia, and keel bone attributes to control hens. In conclusion, the provision of ALA and DHA to breeders and their offspring did not alleviate the negative effects of LPS on eggshell, tibia, and keel bone characteristics in laying hens.

Influence of dietary genistein and polyunsaturated fatty acids on lipid peroxidation and fatty acid composition of meat in quail exposed to heat stress

This experiment was conducted to investigate the effects of polyunsaturated fatty acids (PUFA) and genistein on performance and meat fatty acid profiles in quail exposed to heat stress. A total of 360 Japanese quail were divided into 12 groups in a 2 × 2 × 3 factorial design; each group comprised 30 quail with five replicates and were kept either at 22 ± 2 °C for 24 h/day (Thermoneutral, TN) or 34 ± 2 °C for 8 h/day (08:00 to 17:00 h) followed by 22 °C for 16 h (heat stress, HS) conditions. The diet contained either two levels of PUFA at 15 or 45% of total fat or three levels of genistein at 0, 400, or 800 mg/kg. Bodyweight gain, feed intake, and feed efficiency were lower (p ≥ 0.01) for quail reared under heat stress and fed low PUFA. Increasing dietary genistein in a linear manner improved the productive performance (p < 0.001). Heat stress caused increases in serum and thigh meat malondialdehyde (MDA) concentrations and decreases in genistein and vitamin E and A concentrations in serum and thigh meat (p < 0.001). High PUFA (PUFA45) in the diet of quail caused greater 18:2, 18:3 ALA, EPA, DHA, n-6, and n-3 PUFA as well as total PUFA and total USFA percentages (p < 0.001) in the thigh muscle, some of which decreased with heat stress (p ≥ 0.006) with no regard to genistein supplementation. This study revealed that genistein with greater doses along with greater PUFA inclusion to the diet of quail reared under heat stress is recommended for alleviating adverse effects of heat stress and for yielding healthier meat for human consumption.

Oregano essential oil in the diet of laying hens in winter reduces lipid peroxidation in yolks and increases shelf life in eggs

We evaluated the effects of oregano essential oil (OEO) added to the feed of semi-heavy laying hens during winter. We measured performance as well as physical and chemical quality of fresh and 21-day stored eggs. A total of 240 semi-heavy laying hens were distributed into six treatments and five replicates (n = 8 each). Treatments consisted of five groups of hens fed diets supplemented with 0, 50, 100, 150 and 200 mg OEO/kg. We measured the average of three productive cycles (1st: week 1-4, 2nd: week 5-8 and 3rd: week 9-12), and found that feed consumption increased in hens in the control group and those in the group treated with 200 mg OEO/kg; other zootechnical variables did not differ between treatments. When we analyzed each individual production cycle individually, we did not observe differences between treatments for the performance variables in the first or second cycles. However, in the third cycle, when the animals were exposed to a greater number of days to cold stress, we recorded improved conversion rate/dozen eggs, conversion rate/daily feed consumed and egg production at T50 (50 mg OEO/kg). Stored eggs from hens supplemented with 50 mg OEO/kg showed lower eggshell percentages and higher yolk pHs. The intensity of the yellow was higher in yolks of the control group and in those from hens supplemented with 200 mg OEO/kg. Lipid peroxidation was lower in fresh egg yolks from hens that received 200 mg OEO/kg and stored eggs of T150. The reduction of lipid peroxidation in egg yolk is beneficial to consumer health by reducing levels of free radicals consumed. Reduction of lipid peroxidation associated with 150 mg OEO/kg in laying hens in winter might be useful for maintaining egg quality and for prolonging shelf life; productive efficiency was improving even at 39.8 mg OEO/kg if we consider feed conversion (kg/kg).

Omega-3 and Omega-6 Fatty Acids in Poultry Nutrition: Effect on Production Performance and Health

Omega-3 (ω-3) and omega-6 (ω-6) fatty acids are important components of cell membranes. They are essential for health and normal physiological functioning of humans. Not all fatty acids can be produced endogenously owing to the absence of certain desaturases; however, they are required in a ratio that is not naturally achieved by the standard diet of industrialized nations. Poultry products have become the primary source of long-chain polyunsaturated fatty acids (LC-PUFA), with one of the most effective solutions being to increase the accretion of PUFAs in chicken products via the adjustment of fatty acids in poultry diets. Several studies have reported the favorable effects of ω-3 PUFA on bone strength, bone mineral content and density, and semen quality. However, other studies concluded negative effects of LC-PUFA on meat quality and palatability, and acceptability by consumers. The present review discussed the practical application of ω-3 and ω-6 fatty acids in poultry diets, and studied the critical effects of these fatty acids on productive performance, blood biochemistry, immunity, carcass traits, bone traits, egg and meat quality, and semen quality in poultry. Future studies are required to determine how poultry products can be produced with higher contents of PUFAs and favorable fatty acid composition, at low cost and without negative effects on palatability and quality.

Effects of Dietary Conjugated Linoleic Acid and Selected Vegetable Oils or Vitamin E on Fatty Acid Composition of Hen Egg Yolks

The objective of this study was to produce eggs enriched with conjugated linoleic acid (CLA) and ameliorate their fatty acid profile using the appropriate combination of dietary CLA with or without vegetable oils (olive oil or rapeseed oil) and vitamin E. In Experiment 1, 25-week-old laying hens were randomly distributed into eight groups of nine. Birds were fed with a standard diet with four different levels of CLA (0.0, 0.5, 0.75, 1.0%) and vegetable oils (olive oil or rapeseed oil, both in the amount of 1.46%). In Experiment 2, hens were randomly distributed into 12 groups of nine. The same four levels of CLA with three doses of vitamin E (0, 150, 300 mg/kg of diet) were applied. In both experiments, eggs were collected twice (at 4 and 8 weeks) for fatty acid profiling using GCMS. The differences between treatment means were considered significant at P<0.05. CLA treatments significantly increased the content of CLA, saturated fatty acids (SFA), and significantly decreased the content of monounsaturated fatty acids (MUFA) in the egg yolk, whereas levels of polyunsaturated fatty acids (PUFA) were unaffected. The vegetable oils used did not prevent the negative effects of CLA effectively. Only after eight weeks of experiment 1 SFA levels were significantly lower, but MUFA levels were significantly higher in groups fed with rapeseed oil compared to groups fed with olive oil. In experiment 2, the addition of vitamin E to the hen diet did not have an essential influence on the lipid profile of egg yolks.

ADIÇÃO DE ÓLEO DE COPAÍBA (Copaifera langsdorffii) E SUCUPIRA (Pterodon emarginatus) NA ALIMENTAÇÃO DE POEDEIRAS: QUALIDADE FÍSICA DE OVOS ARMAZENADOS EM DIFERENTES TEMPERATURAS

Resumo O objetivo deste trabalho foi avaliar os efeitos da adição de óleos vegetais à alimentação de poedeiras semipesadas na qualidade física de ovos armazenados sob refrigeração ® e em temperatura ambiente (TA). As aves receberam ração formulada à base de milho e farelo de soja com a suplementação de níveis crescentes de óleo de Copaifera langsdorffii (CP-0,03; 0,06 e 0,09%) ou Pterodon emarginatus (SC-0,03 e 0,06%) mais um controle negativo (CN). Periodicamente, foram analisados três ovos por tratamento para Unidade Haugh (UH), índice de gema (IG), cor, pH (gema e albúmen) e porcentagens de casca (PC), gema (PG) e albúmen (PA). Para análise estatística dos resultados, foi adotado um modelo misto (SAS 9.3) e as médias foram comparadas pelo teste de Tukey. A inclusão de até CP0,06% CP ou SC0,03% preservou (P<0,05) os valores de UH nos ovos em TA, equivalente aos tratamentos sob R até 14 dias; além disso, a adição dos óleos controlou a elevação do pH das gemas. Concluiu-se que os óleos vegetais suplementados nas dietas de poedeiras influenciaram positivamente na manutenção da qualidade do albúmen e do pH das gemas dos ovos em temperatura ambiente, contudo nenhum efeito adicional foi verificado para os ovos mantidos sob refrigeração.

China's livestock transition: Driving forces, impacts, and consequences

China's livestock industry has experienced a vast transition during the last three decades, with profound effects on domestic and global food provision, resource use, nitrogen and phosphorus losses, and greenhouse gas (GHG) emissions. We provide a comprehensive analysis of the driving forces around this transition and its national and global consequences. The number of livestock units (LUs) tripled in China in less than 30 years, mainly through the growth of landless industrial livestock production systems and the increase in monogastric livestock (from 62 to 74% of total LUs). Changes were fueled through increases in demand as well as, supply of new breeds, new technology, and government support. Production of animal source protein increased 4.9 times, nitrogen use efficiency at herd level tripled, and average feed use and GHG emissions per gram protein produced decreased by a factor of 2 between 1980 and 2010. In the same period, animal feed imports have increased 49 times, total ammonia and GHG emissions to the atmosphere doubled, and nitrogen losses to watercourses tripled. As a consequence, China's livestock transition has significant global impact. Forecasts for 2050, using the Shared Socio-economic Pathways scenarios, indicate major further changes in livestock production and impacts. On the basis of these possible trajectories, we suggest an alternative transition, which should be implemented by government, processing industries, consumers, and retailers. This new transition is targeted to increase production efficiency and environmental performance at system level, with coupling of crop-livestock production, whole chain manure management, and spatial planning as major components.

Strategies for Producing and Incorporating Conjugated Linoleic Acid–Rich Oils in Foods

Conjugated linoleic acid (CLA) is in ruminant-derived foods and is known to combat obesity-related diseases. However, CLA levels in a healthy diet are too low to produce a clinical effect. Therefore, CLA has been produced by linoleic isomerization through fermentation and chemical catalysis. Many of these techniques are not practical for food production, but a recent development has enabled production of CLA-rich triglyceride vegetable oils from high linoleic acid oils by a minor modification of conventional food-oil processing techniques. These oils were used to produce common lipid-based food, such as margarine, shortenings, and salad dressings, whose quality was enhanced by the presence of CLA-rich oil and provided a significant CLA source. Meat and egg CLA content and subsequent food quality can also be increased by addition of dietary CLA. However, consumer awareness of CLA benefits needs to increase prior to commercial-scale production of CLA-rich oil.

Effect of dietary pomegranate seed oil on laying hen performance and physicochemical properties of eggs

The objective of the study was to determine the effects of pomegranate seed oil, used as a source of punicic acid (CLnA) in the diets of laying hens, on the physicochemical properties of eggs. Forty Isa Brown laying hens (26weeks old) were equally subjected to 4 dietary treatments (n=10) and fed a commercial layer diet supplying 2.5% sunflower oil (control) or three levels (0.5, 1.0 and 1.5%) of punicic acid in the diets. After 12weeks of feeding the hens, eggs collection began. Sixty eggs - randomly selected from each group - were analysed for physicochemical properties. Eggs naturally enriched with CLnA preserve their composition and conventional properties in most of the analysed parameters (including chemical composition, physical as well as organoleptic properties). Dietary CLnA had positive impact on the colour of the eggs' yolk, whereas the hardness of hard-boiled egg yolks was not affected. Additionally, increasing dietary CLnA led to an increase not only the CLnA concentrations, but also CLA in egg-yolk lipids.

Effects of conjugated linoleic acid on the performance of laying hens, lipid composition of egg yolk, egg flavor, and serum components

OBJECTIVE

This experiment investigated the effects of dietary supplementation with conjugated linoleic acid (CLA) on the serum components, laying hen productivity, lipid composition of egg yolk, egg flavor and egg quality.

METHODS

Healthy 28-week-old Hy-Line white laying hens (n = 480) were divided randomly into 4 groups, 6 replicates/group, 20 birds/replicate. The 30-day experimental diets included 0% (control), 0.4%, 0.8%, and 1.6% CLA. Some serum indices of the birds, and egg production, quality, fatty acid composition, egg quality were measured.

RESULTS

The dietary supplementation with 0.4%, 0.8%, and 1.6% CLA did not significantly affect the laying rate and feed intake, as well as calcium ion and phosphorus ion concentration in serum (p>0.05). However, the CLA had significantly increased the strength of eggshell, decreased the odor, flavor, and taste of egg yolk, deepened the color of egg yolk, increased saturated fatty acids and polyunsaturated fatty acids, and reduced the monounsaturated fatty acids (p<0.05). On the other hand, the dietary supplementation with 1.6% CLA had significant effects on feed/gain, and improved serum hormones. Dietary supplementation with 0.4% and 0.8% CLA can significantly enhance the activity of alkaline phosphates.

CONCLUSION

CLA has no effect on production performance, but does enhance the lipid content of the egg yolk and the strength of the eggshell.

Effect of trans, trans CLA egg enrichment from CLA-rich soy oil on yolk fatty acid composition, viscosity and physical properties

CLA egg accumulation studies using cis, trans (c,t) isomers have been effective, but they reported adverse egg quality. trans, trans (t,t) CLA isomers have shown superior nutritional effects in rodent studies, but reports of t,t CLA-rich yolks are limited. The objectives were to determine the effect of t,t CLA-rich soy oil in feed on egg yolk viscosity, and yolk quality during refrigerated storage. Yolk fatty acids, viscosity, weight, index, moisture, pH, and vitelline membrane strength (VMS) were determined at 0, 20, and 30 storage days. CLA had minimal effect on fatty acid profiles, relative to c,t reports. CLA-rich yolk viscosity was greater than controls, and CLA yolks maintained higher viscosities during storage. Yolk weight and index were not affected by t,t CLA-rich soy oil. Yolks with the greatest CLA concentrations had the greatest VMS after 20 days of storage, and yolks containing lower CLA levels maintained greater VMS throughout 30 days of storage, relative to controls.

Qualidade de ovos de codorna submetidos ou não a tratamento superficial da casca armazenados em diferentes ambientes

Com o objetivo de avaliar a qualidade de ovos de codornas japonesas tratados superficialmente, através de imersão em óleo mineral ou solução de própolis, foram conduzidos experimentos simultâneos em dois ambientes, sem refrigeração (Experimento 1) e com refrigeração (Experimento 2). Para cada experimento, foram selecionados 360 ovos íntegros distribuídos em delineamento inteiramente casualizado em esquema fatorial 3 x 5 (ovos não tratados; ovos imersos em solução de própolis e ovos imersos em óleo mineral, avaliados durante cinco tempos de armazenamento: 7; 14; 21; 28 e 35 dias), cada tratamento foi composto por seis repetições de quatro ovos cada. Os ovos apresentaram aumento da perda de peso, diminuição do peso específico e aumento do peso e do pH da gema, além de redução do pH do albúmen e de seu respectivo peso com o avançar do tempo de estocagem na ausência de refrigeração (Experimento 1), independente se receberam ou não tratamento na casca. Entretanto, o tratamento superficial com óleo mineral promoveu proteção contra essa perda progressiva de peso e diminuição do peso específico, tornando-as menos intensas com o avançar do período de estocagem sem refrigeração. No Experimento 2, a imersão dos ovos em óleo mineral conferiu menor perda de peso, maior peso específico, maior peso de gema e de albúmen durante o armazenamento sob refrigeração. A qualidade de ovos de codornas submetidos a tratamento superficial da casca por imersão em óleo mineral é preservada por até cinco semanas em diferentes ambientes, sem e com refrigeração.

Egg quality and yolk lipid composition of laying hens fed diets containing cashew nut meal

The objective of this study was to assess the effect of the addition of cashew nuts meal (0, 5, 10, 15, 20, and 25%) to laying hen diets on egg quality and yolk composition. The variables studied were: egg weight, specific gravity, Haugh Units, percentages of shell, albumen, and yolk, moisture, total solids, total lipids, fatty acids profile, and yolk cholesterol. The addition of up to 25% of cashew nuts meal to hen diets did not affect egg quality and freshness, moisture and total solids content. However, an increase in total lipid content and a decrease in yolk pigmentation was observed. Oleic acid level increased in the yolk, whereas palmitic, stearic, and linoleic acid levels decreased. The addition of cashew nuts meal increased the monounsaturated/saturated fatty acid ratio in the yolk and reduced the cholesterol content. Therefore, the use of cashew nuts meal in laying hen diets favorably modifies the fatty acid composition of egg yolk and contributes to a better acceptance of this food by consumers since it also reduces yolk cholesterol levels.

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.

Evidence that maternal conjugated linoleic acid negatively affects lipid uptake in late-stage chick embryos resulting in increased embryonic mortality

An experiment was performed to determine the effect of maternal dietary conjugated linoleic acid (CLA) on growth and composition of surviving chick embryos and residual yolk sacs during the last week of development when lipid utilization becomes prevalent. After 14 d on experimental diets, hatchability of non-cooled eggs obtained from CLA-fed hens (0.5% of the diet) was 10%, where 20% of surviving CLA embryos died after d 13 of incubation. Hatchability was 93% for controls and only 4.36% of mortality occurred after d 13 of incubation. Decline in yolk sac weight in control embryos (0.75 g/d) was significantly greater than that from viable CLA embryos (0.51 g/d). Growth rate (2.6 g/d) of surviving embryos from d 13 to 20 was reduced in CLA embryos in comparison to growth rate of controls (3.0 g/d). Relative proportion of lipid in residual yolk sacs in embryos from control-fed hens decreased from 26.72% (d 13) to 15.94% (d 19) during incubation, whereas little change was evident in residual yolk sac from CLA embryos on d 13 (21.52%) to d 19 (20.39%). Fatty acid analysis of residual yolk sac contents suggested that transport of fatty acids from the contents (liquid yolk) to the yolk sac membrane was not impaired in CLA embryos, as shown by a similar pattern in reduction of total fatty acids in residual yolk sac contents between treatment groups. Apart from 18:1n-9 (d 17), there were no consistent differences in the fatty acid content between embryos from hens fed the control diet or the CLA diet at any time point. Maternal CLA led to increased 18:0 and decreased 18:1n-9 in yolk lipid and embryonic tissues compared with controls across time. These findings could possibly suggest that CLA embryos had less capacity to use yolk lipids from the residual yolk sac during the last week of incubation.

Evidence for conjugated linoleic acid-induced embryonic mortality that is independent of egg storage conditions and changes in egg relative fatty acids

Three experiments were performed to determine the effect of conjugated linoleic acid (CLA) on embryonic development in the absence of vitelline membrane disruption. In experiment 1, when eggs from control and CLA (0.5%)-fed hens were stored at 21 or 15 degrees C for 48 h, mineral movement between the yolk and albumen was not observed (with the exception of Mg and Na). Also, it was found that CLA-induced changes in yolk fatty acid content (e.g., increased saturated fatty acids and CLA) had begun to change after 5 d of feeding hens CLA, and no differences were detected in fatty acid composition after 14 d. In experiment 2, the hatchability of eggs incubated directly after oviposition or stored 24 h at 21 or 15 degrees C was determined from hens fed control or 0.5% CLA diets. Regardless of storage conditions, CLA reduced hatchability. These data showed that CLA elicits negative effects on hatchability independent of vitelline membrane disruption or egg storage condition. In experiment 3, eggs were collected from hens fed 0 or 1% CLA daily for 3 wk, stored at 21 degrees C for 24 h, and incubated. Not only did CLA decrease hatchability, the data showed as the days of CLA feeding increased, the days of survival during incubation decreased. Average days of embryonic survival during incubation for the CLA group diminished to 18.0, 13.4, and 6.3 d for wk 1, 2, and 3 of CLA feeding, respectively, and control remained at 20.6, 20.8, and 19.8 for the 3 wk. These studies suggested that without the disruption of the vitelline membrane, hatchability and embryonic days of survival were significantly reduced by maternal CLA feeding in comparison to control-fed hens. Evidence that embryos die earlier the longer the hens are fed CLA, even though no additional changes in the fatty acid content of eggs were found, suggested that factors other than storage and egg yolk fatty acid composition played a role in CLA-induced embryonic mortality.

Functional effects of eggs, naturally enriched with conjugated linoleic acid, on the blood lipid profile, development of atherosclerosis and composition of atherosclerotic plaque in apolipoprotein E and low-density lipoprotein receptor double-knockout mice (apoE/LDLR− / − )

The objective of this study was to evaluate potential anti-atherogenic properties of hen eggs enriched naturally with conjugated linoleic acid (CLA) isomers (cis-9,trans-11 andtrans-10,cis-12). Eighteen apoE and LDL receptor double-knockout mice (apoE/LDLR− / − ), at the age of 4 months with pre-established atherosclerosis, were randomly assigned to three experimental groups (n6) and fed AIN-93G-based diets for the next 2 months. The experimental diets were: AIN-93G+ CLA-free egg-yolk powder (control); AIN-93G+ CLA-free egg-yolk powder +0·1 % CLA (CLA-supplemented eggs); and AIN-93G+ CLA-enriched egg-yolk powder, providing 0·1 % CLA (CLA-enriched eggs). For assessment of anti-atherogenic properties of CLA-enriched or CLA-supplemented eggs the following criteria were used: (1) serum lipid profile; (2) development of atherosclerosis; and (3) composition of atherosclerotic plaque. CLA-enriched eggs, compared with CLA-supplemented eggs, reduced significantly (P < 0·05) total plasma cholesterol in the mice. At the same time, both CLA-supplemented eggs and CLA-enriched eggs tended to decrease the size of atherosclerotic plaque in aortic roots of mice. Most importantly, atherosclerotic plaques of mice fed CLA-enriched eggs showed significantly (P < 0·05) reduced number of atherogenic macrophages and increased area occupied by smooth muscle cells in atherosclerotic lesions. In conclusion, CLA-enriched eggs exerted an anti-inflammatory effect more effectively than CLA-supplemented eggs. This anti-inflammatory effect can be considered their major functional claim that warrants further exploitation.

Effect of Dietary Supplementation with Conjugated Linoleic Acid, with Oleic, Linoleic, or Linolenic Acid, on Egg Quality Characteristics and Fat Accumulation in the Egg Yolk

The effects of conjugated linoleic acid (CLA) with other fatty acids on the fatty acid composition of egg yolk and on egg quality characteristics were studied in 5 groups: 1) CLA 0% (control), 2) CLA 2%, 3) CLA 2%+oleic acid (OA) 2% (CLA+OA), 4) CLA 2%+linoleic acid (LA) 2% (CLA+LA), and 5) CLA 2%+alpha-linolenic acid (LNA) 2% (CLA+LNA). Some parameters of egg quality such as shell thickness, shell strength, yolk color, yolk index, egg diameter, and Haugh units were aggravated when CLA was fed alone, but the quality was improved when CLA was combined with some other fatty acids. The egg production rate, which was decreased by feeding CLA alone, was improved by co-supplementation with LA or OA. An increase in CLA content was observed in all the dietary groups fed CLA for 2 wk. Feeding hens with CLA+LNA led to a linear increase in CLA content in the egg yolk after the fourth week of the feeding trial. Egg yolks from hens given CLA had considerably higher amounts of saturated fatty acids and lower amounts of monounsaturated fatty acids than egg yolks from the control group. The pattern of change in CLA concentration during the feeding trial was similar to the level of C18:0, which was inversely correlated with the level of C18:1. The unsaturated fatty acid co-supplementation strategy applied in this study offers insight into the mechanism of CLA accumulation in the egg yolk without apparent adverse effects on egg quality and egg production.

Effects of Conjugated Linoleic Acid Supplementation in Layer Diet on Fatty Acid Compositions of Egg Yolk and Layer Performances

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds. Conjugated linoleic acids have been reported to have a wide range of health-beneficial effects, including anticarcinogenic, antiatherogenic, antidiabetic, and immune stimulatory effects. The objective of this study was to investigate the incorporation of CLA into eggs. Three hundred 27-wk-old layers were allocated to 5 dietary treatments (0, 1, 2, 3, and 4% CLA) with 5 replicates. The results of the study showed that average daily feed intakes were similar in all treatment groups, although hens fed with 4% CLA tended to consume less feed than other hens. Body weight gain and mortality rate were not significantly different (P > 0.05). Hens fed 4% dietary CLA had reduced egg, yolk, and albumen weights (P < 0.05). Yolk color significantly decreased as dietary CLA increased (P < 0.01). Shell thickness and Haugh units were not influenced by the dietary CLA. Concentrations of CLA and saturated fatty acids in egg yolk lipids increased as dietary CLA increased (P < 0.01), whereas concentrations of monounsaturated fatty acids and polyunsaturated fatty acids decreased as dietary CLA increased (P < 0.01). It can be concluded from the present experiments that increasing the amount of CLA fed to hens will increase the amount of CLA in egg yolk and that this increase is accompanied by a reduction in the amount of yolk polyunsaturated fatty acids but an increase in yolk saturated fatty acids. Egg size, yolk weight, and Roche-fan determined yolk color significantly decreased at the highest level of CLA supplementation.

Effect of dietary conjugated linoleic acid on the fatty acid composition of egg yolk, plasma and liver as well as hepatic stearoyl-coenzyme A desaturase activity and gene expression in laying hens

A total of 216 Brown Dwarf laying hens (1.62 +/- 0.06 kg BW and 60 wk old) were fed 1 of 3 corn-soybean meal-based diets containing 0, 2.5, or 5.0% conjugated linoleic aicd (CLA) to explore its effects on the fatty acid composition of egg yolk, plasma, and liver as well as hepatic stearoyl-coenzyme A desaturase-1 (SCD-1) activity and its mRNA gene expression. Four hens were placed in wired-floored cages (45 x 40 x 45 cm) and 3 cages were grouped as 1 replicate, resulting in 6 replicates per treatment. The experimental diets were fed for 54 d, and then eggs were collected to determine the fatty acid composition of egg yolk. Four eggs were randomly selected from the total day's production for each replicate, and the contents were pooled prior to analysis. On d 56, one randomly chosen hen from each replicate (6 hens per replicate and a total of 18 hens) was bled via heart puncture and then killed in order to collect liver samples to measure the fatty acid profile of plasma and liver tissue as well as hepatic SCD-1 activity and its mRNA abundance. Dietary supplementation of CLA resulted in a significant deposition of CLA in egg yolk, plasma, and liver lipids (P < 0.01). As the dietary level of CLA increased, the concentration of saturated fatty acids in egg yolk, plasma, and liver also increased (P < 0.05). However, the concentration of monounsaturated fatty acids in these same tissues decreased (P < 0.01). Compared with the control, the activity of SCD-1 was reduced by feeding 2.5% CLA (P < 0.05) without a change in SCD-1 mRNA gene expression. However, feeding 5% CLA reduced both SCD-1 activity and mRNA abundance (P < 0.05). These results indicate that the conversion of saturated to monounsaturated fatty acids in egg yolk, plasma, and liver might be modulated directly at hepatic mRNA gene expression levels, or may be indirectly regulated at the downstream post-transcriptional levels.