Method for improving the quality of Silkie chicken eggs, Silkie chicken eggs with enhanced antioxidant activity, Silkie chicken feed, and method for producing the same.

Abstract

To provide a method for improving the quality of silky eggs, and to provide silky eggs with enhanced antioxidant activity.SOLUTION: Provided is a method for improving the quality of silky eggs, characterized by orally feeding a feed containing 8.5 mg / kg or more of carotenoids derived from Capsicum annuum and / or 24.4 mg / kg or more of carotenoids derived from Tagetes petals to a silky for at least 7 days or more. According to the present method, a silky egg with enhanced antioxidant activity is provided, the egg yolk of which has an antioxidant activity that is more than twice as high as that of a regular chicken egg. The present invention also provides a feed for silkies and a method for producing the same.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a method for improving the quality of Silkie chicken eggs and to Silkie chicken eggs with enhanced antioxidant activity. [Background technology]

[0002] Laying hens often have paprika or marigold, which are rich in carotenoids, added to their feed to differentiate the color of their egg yolks. Lutein, zeaxanthin, and astaxanthin, found in these foods, are carotenoids that have recently attracted attention not only for their coloring effect on egg yolks but also for their antioxidant properties.

[0003] On the other hand, the Silkie chicken is believed to have been introduced to Japan from China in the early Edo period, and according to the Chinese herbal medicine text "Bencao Gangmu," the eggs and meat of the Silkie chicken are described as having medicinal properties. In fact, in China and Korea, the Silkie chicken has long been highly valued as an ingredient in medicinal cuisine.

[0004] The applicant in this case, the Tokyo Metropolitan Agriculture, Forestry and Fisheries Promotion Foundation, has been working on improving the Silkie chicken breed for some time and has created a high-egg-laying Silkie chicken called "Tokyo Ukokkei," which increases the egg-laying rate from the usual 50 to 80 eggs per year to about 200 eggs per year.

[0005] Furthermore, the applicant, the Tokyo Metropolitan Agriculture, Forestry and Fisheries Promotion Foundation, has revealed that the metabolism of Silkie chickens differs from that of ordinary chickens (see Non-Patent Document 1). In addition, the Foundation holds a patent for a method of suppressing the production of lipid peroxides in the meat of Silkie chickens by feeding them Angelica keiskei (see Patent Document 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Kojima S, et al., Food Science and Technology Research, 20: 621-628. 2014.

Patent Document

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] As described above, it is well known that dietary carotenoids improve egg yolk color, but the effects on other qualities of chicken eggs (e.g., antioxidant function) have not been fully investigated.

[0009] In addition, in black-boned chickens with different metabolism compared to general chickens, the effects of dietary carotenoids on egg quality are unclear. In order to further expand the utilization of black-boned chicken eggs, the development of black-boned chicken eggs with higher added value has been demanded.

[0010] An object of the present invention is to provide a method for improving the egg quality of black-boned chickens. Another object of the present invention is to provide black-boned chicken eggs with enhanced antioxidant activity.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above problems, the present inventors surprisingly found that by orally administering carotenoids to black-boned chickens, more carotenoids (especially lutein and zeaxanthin) migrate into black-boned chicken eggs compared to general chicken eggs. It was also found that the antioxidant activity of black-boned chicken eggs is enhanced more than that of general chicken eggs by oral administration of carotenoids. Based on these findings, the present inventors completed the present invention.

[0012] In other words, the present invention provides a method for improving the quality of Silkie chicken eggs, characterized by orally feeding Silkie chickens a feed containing 8.5 mg / kg or more of paprika-derived carotenoids and / or 24.4 mg / kg or more of marigold petal-derived carotenoids for at least 7 days.

[0013] Here, "quality improvement" includes increasing the carotenoid content of egg yolks and / or enhancing the antioxidant activity (particularly singlet oxygen scavenging activity) of egg yolks.

[0014] Therefore, the method for improving the quality of Silkie chicken eggs according to the present invention may also be a method for increasing the carotenoid content of Silkie chicken eggs. Alternatively, the method for improving the quality of Silkie chicken eggs according to the present invention may also be a method for increasing the antioxidant activity (particularly singlet oxygen scavenging activity) of Silkie chicken eggs.

[0015] According to the method for enhancing the carotenoid content of Silkie chicken eggs, it is possible to obtain Silkie chicken eggs in which the zeaxanthin content in the yolk is 1 mg / 100g or more, and / or the lutein content is 4 mg / 100g or more.

[0016] According to the method for enhancing the antioxidant activity of Silkie chicken eggs, it is possible to obtain Silkie chicken eggs with yolk antioxidant activity more than twice as high as that of regular chicken eggs.

[0017] Also, the Silkie chicken can be called "Tokyo Ukokkei".

[0018] The present invention provides Silkie chicken eggs with enhanced antioxidant activity, characterized in that the egg yolk has more than twice the antioxidant activity of ordinary chicken eggs.

[0019] Here, "antioxidant activity" may also refer to singlet oxygen scavenging activity.

[0020] The Silkie chicken eggs may further contain zeaxanthin in the yolk at a rate of 1 mg / 100g or more, and / or lutein at a rate of 4 mg / 100g or more.

[0021] The present invention provides a feed for Silkie chickens, characterized by containing 8.5 mg / kg or more of carotenoids derived from paprika and / or 24.4 mg / kg or more of carotenoids derived from marigold petals.

[0022] The present invention also provides a method for producing feed for Silkie chickens, characterized by incorporating 8.5 mg / kg or more of paprika-derived carotenoids and / or 24.4 mg / kg or more of marigold petal-derived carotenoids into the feed.

[0023] In this case, the feed for Silkie chickens may be intended to enhance the antioxidant activity of the egg yolk. [Effects of the Invention]

[0024] The present invention provides a method for improving the quality of Silkie chicken eggs. Specifically, by feeding Silkie chickens a diet containing a predetermined proportion of carotenoids derived from paprika and / or marigold petals, carotenoids (especially lutein and zeaxanthin) can be efficiently transferred to the eggs compared to ordinary chickens. In this way, the antioxidant function of the carotenoids accumulated in the eggs makes it possible to obtain Silkie chicken eggs with antioxidant activity (especially singlet oxygen scavenging activity) that is more than twice as high as that of ordinary chicken eggs.

[0025] According to the present invention, it is possible to provide Silkie chicken eggs with enhanced antioxidant activity. Ingesting Silkie chicken eggs with high antioxidant function is expected to suppress lipid oxidation in the body and reduce the production of lipid peroxides, which have adverse effects on health. Furthermore, due to their high antioxidant function, they are expected to be effective in maintaining or improving health by eliminating reactive oxygen species, which have been linked to cancer and accelerated aging. [Brief explanation of the drawing]

[0026] [Figure 1]This graph shows the total carotenoid content in egg yolks (Test Example 1). Data are expressed as mean ± SE (n=3). There is a significant difference between different signs within the same graph (P<0.05) in a-c. Cont = basal feed; PA = basal feed with 30 mg / kg of paprika-derived carotenoids added; MA = basal feed with 60 mg / kg of marigold petal-derived carotenoids added; AX = basal feed with 28 mg / kg of Paracoccus cell powder-derived carotenoids added. RR = Rhode Island Red; SF = Silkie chicken. [Figure 2] This graph shows the content of (A) zeaxanthin, (B) lutein, and (C) astaxanthin in egg yolk (Test Example 1). Data are expressed as mean ± SE (n=5). There is a significant difference between a-c with different signs within the same graph (P<0.05). Cont = basal feed; PA = basal feed with 30 mg / kg of paprika-derived carotenoids added; MA = basal feed with 60 mg / kg of marigold petal-derived carotenoids added; AX = basal feed with 28 mg / kg of Paracoccus cell powder-derived carotenoids added. RR = Rhode Island Red; SF = Silkie chicken. [Figure 3] This graph shows the singlet oxygen scavenging activity (50% inhibitory concentration; IC50) by egg yolk (Test Example 1). Data are expressed as mean ± SE (n=3). There is a significant difference between the same graph with different signs in a-c (P<0.05). Cont = basal feed; PA = basal feed with 30 mg / kg of paprika-derived carotenoids added; MA = basal feed with 60 mg / kg of marigold petal-derived carotenoids added; AX = basal feed with 28 mg / kg of Paracoccus cell powder-derived carotenoids added. RR = Rhode Island Red; SF = Silkie chicken. [Figure 4]This graph shows the change in egg yolk color over time for (A) Rhode Island Red and (B) Silkie chickens (Test Example 1). The data is expressed as the mean value (n=12). Cont = base feed; PA = base feed with 30 mg / kg of carotenoids derived from paprika extract added; MA = base feed with 60 mg / kg of carotenoids derived from marigold petal extract added; AX = base feed with 28 mg / kg of carotenoids derived from Paracoccus cell powder added. [Figure 5] This graph shows the content of (A) zeaxanthin, (B) lutein, and (C) astaxanthin in egg yolk (Test Example 2). Data are expressed as mean ± SE (n=4). There is a significant difference between a-c with different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; PA = 60 mg / kg of paprika-derived carotenoids added; MA = 120 mg / kg of marigold petal-derived carotenoids added; AX = 56 mg / kg of Paracoccus cell powder-derived carotenoids added. [Figure 6] This graph shows the singlet oxygen scavenging activity (50% inhibitory concentration; IC50) by egg yolk (Test Example 2). Data are expressed as mean ± SE (n=3). There is a significant difference between the same graph with different signs in a-d (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; PA = 60 mg / kg of paprika-derived carotenoids added; MA = 120 mg / kg of marigold petal-derived carotenoids added; AX = 56 mg / kg of Paracoccus cell powder-derived carotenoids added. [Figure 7]This graph shows the content of (A) lutein, (B) zeaxanthin, and (C) astaxanthin in egg yolk (Test Example 3). Data are expressed as mean ± SE (n=5). There is a significant difference between a-c with different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = basal feed; MA+PA = basal feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 15 mg / kg of carotenoids derived from paprika; MA+AX = basal feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 14 mg / kg of carotenoids derived from Paracoccus bacteria powder. [Figure 8] This graph shows the singlet oxygen scavenging activity (50% inhibitory concentration; IC50) by egg yolk (Test Example 3). Data are expressed as mean ± SE (n=3). There is a significant difference between the same graph with different signs in a-c (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = basal feed; MA+PA = basal feed supplemented with 30 mg / kg of carotenoids derived from marigold petals + 15 mg / kg of carotenoids derived from paprika; MA+AX = basal feed supplemented with 30 mg / kg of carotenoids derived from marigold petals + 14 mg / kg of carotenoids derived from Paracoccus bacteria powder. [Modes for carrying out the invention]

[0027] The embodiment will be described in detail below.

[0028] The method for improving the quality of Silkie chicken eggs according to this embodiment is characterized by orally administering carotenoids derived from paprika and / or carotenoids derived from marigold petals to Silkie chickens for at least 7 days.

[0029] The "Silkie chicken" is a breed of chicken. However, unlike common chickens, Silkie chickens have distinctive physical characteristics such as having more toes on their feet and downy feathers, as well as being black in color, from their skin and meat to their bones.

[0030] As a specific example of a Silkie chicken, one can cite "Tokyo Ukokkei," a high-egg-laying Silkie chicken breed developed by the applicant, the Tokyo Metropolitan Agriculture, Forestry and Fisheries Promotion Foundation. This "Tokyo Ukokkei" is a breed with excellent egg-laying ability.

[0031] Silkie chickens used are female silkie chickens specifically raised for egg production. Generally, egg-laying hens reach sexual maturity and begin laying eggs around 5 months after hatching (5 months of age), and are used for egg production for about 1 to 1.5 years thereafter. Therefore, female silkie chickens that are 5 months to 2 years old are preferably used.

[0032] "Paprika-derived carotenoids" refers to carotenoids contained in the fruit of paprika, a plant belonging to the nightshade family. The form in which carotenoids are given is not particularly limited as long as there are no problems with feeding them to Silkie chickens, and may be in the form of dried and crushed paprika powder or paprika extract.

[0033] "Paprika extract" refers to a product obtained by extracting carotenoids, including zeaxanthin, from paprika fruit, and the extraction method is not limited. Furthermore, paprika extract may also be a paprika extract product obtained by saponification after extracting carotenoids with an organic solvent.

[0034] Furthermore, powdered compound feed prepared by mixing paprika powder or paprika extract with multiple feed ingredients can also be used as "paprika-derived carotenoids." Specific examples of such compound feeds include RunRed (registered trademark) (Elanco Japan Co., Ltd.), ColorUp (Kokin Chemical Co., Ltd.), ChiliRed 10, Pixafil Red HY-C15 (Yamato Chemical Co., Ltd.), and CapsaRed (Asuka Animal Health Co., Ltd.).

[0035] "Carotenoids derived from marigold petals" refers to carotenoids contained in the petals of marigolds, which are plants of the Asteraceae family. The form in which the carotenoids are administered is not particularly limited as long as it does not cause any problems when being given to Silkie chickens, and may be in the form of dried and crushed marigold petal powder or marigold petal extract.

[0036] "Marigold petal extract" refers to a product obtained by extracting carotenoids, including lutein, from marigold petals, and the extraction method is not limited. Furthermore, the marigold petal extract may also be a marigold petal extract product obtained by saponification after extracting carotenoids with an organic solvent.

[0037] Furthermore, powdered compound feed prepared by mixing marigold petal powder or marigold petal extract with multiple feed ingredients can also be used as "carotenoids derived from marigold petals." Specific examples of such compound feeds include Xan Yellow (registered trademark) (Elanco Japan Co., Ltd.), Color Up Yellow S (Kokin Chemical Co., Ltd.), and Dynefil S20 (Yamato Chemical Co., Ltd.). Zeaxanthin may also be included in marigold petal extract.

[0038] Typically, carotenoids derived from paprika and / or marigold petals are added to and mixed into the basal feed and administered orally. There are no special restrictions on the basal feed; any feed commonly used for raising egg-laying hens is acceptable, and commercially available compound feeds can be used as desired.

[0039] The amount of paprika-derived carotenoids in the basal feed can be 8.5 mg / kg or more, preferably 8.5 to 90 mg / kg, more preferably 15 to 60 mg / kg, and particularly preferably 30 to 60 mg / kg, as total carotenoids. Alternatively, the amount of paprika-derived carotenoids in the basal feed can be 0.714 mg / kg or more, preferably 0.714 to 7.56 mg / kg, more preferably 1.26 to 5.04 mg / kg, and particularly preferably 2.52 to 5.04 mg / kg, as zeaxanthin.

[0040] The amount of carotenoids derived from marigold petals in the basal feed can be 24.4 mg / kg or more, preferably 24.4 to 160 mg / kg, more preferably 30 to 120 mg / kg, and particularly preferably 60 to 120 mg / kg, as total carotenoids. Alternatively, the amount of marigold petal extract in the basal feed can be 14.52 mg / kg or more, preferably 14.52 to 95.2 mg / kg, more preferably 17.85 to 71.4 mg / kg, and particularly preferably 35.7 to 71.4 mg / kg, as lutein.

[0041] If the amount of paprika and / or marigold petal-derived carotenoids in the basal feed is below the above range, a sufficient improvement in egg quality cannot be obtained. On the other hand, if the amount of paprika and / or marigold petal-derived carotenoids in the basal feed exceeds the above range, not only is the advantage of Silkie chickens over general chickens lost, but the improvement in egg quality commensurate with the amount added is not obtained, making it uneconomical and therefore undesirable. Furthermore, paprika-derived carotenoids and marigold petal-derived carotenoids can be used in combination within the above range of amounts.

[0042] The period for administering carotenoids derived from paprika and / or marigold petals can be at least 7 days, preferably 10 days or more, and more preferably 14 days or more. If the administration period is too short, a sufficient effect on improving egg quality will not be obtained.

[0043] According to the above-described method for improving the quality of Silkie chicken eggs, the carotenoid content (especially lutein and zeaxanthin) in the egg yolk of Silkie chicken eggs can be increased, thereby providing Silkie chicken eggs with high antioxidant activity.

[0044] Therefore, according to this embodiment, a method for increasing the carotenoid content of Silkie chicken eggs is provided, characterized by orally administering paprika-derived carotenoids and / or marigold petal-derived carotenoids to Silkie chickens for at least 7 days.

[0045] According to the method for enhancing the carotenoid content of Silkie chicken eggs, Silkie chicken eggs can be obtained in which the zeaxanthin content in the egg yolk is 1 mg / 100g or more, preferably 1.2 mg / 100g or more of egg yolk, and / or the lutein content is 4 mg / 100g or more, preferably 5 mg / 100g or more of egg yolk. The carotenoid content can be measured by the method described in Example (Test Example 1).

[0046] Furthermore, according to this embodiment, a method for enhancing the antioxidant activity of Silkie chicken eggs is provided, characterized by orally administering paprika-derived carotenoids and / or marigold petal-derived carotenoids to Silkie chickens for at least 7 days.

[0047] In this specification, "antioxidant activity" specifically refers to the scavenging activity against reactive oxygen species, and preferably to singlet oxygen scavenging activity.

[0048] According to the method for enhancing the antioxidant activity of Silkie chicken eggs, it is possible to obtain Silkie chicken eggs with yolk antioxidant activity more than twice as high as that of ordinary chicken eggs. The antioxidant activity (singlet oxygen scavenging activity) of the yolk can be measured by the method described in Example (Test Example 1).

[0049] The Silkie chicken eggs of this embodiment have an enhanced carotenoid content (particularly lutein and zeaxanthin), resulting in improved egg yolk color. Furthermore, because the antioxidant activity of the Silkie chicken eggs of this embodiment is enhanced, consuming them is expected to have functional benefits such as suppressing the production of lipid peroxides in the body and eliminating reactive oxygen species.

[0050] Furthermore, according to this embodiment, a feed for Silkie chickens is provided that contains the carotenoids derived from paprika and / or the carotenoids derived from marigold petals in the aforementioned amounts. This feed for Silkie chickens can be produced by adding the carotenoids derived from paprika and / or the carotenoids derived from marigold petals to the feed in the aforementioned amounts. Here, "feed" is the same as the basic feed described above.

[0051] As mentioned above, orally feeding this feed to Silkie chickens can increase the carotenoid content of the egg yolk, thereby enhancing the antioxidant activity of the egg yolk, particularly its singlet oxygen scavenging activity. Therefore, this feed can be used to improve the quality of Silkie chicken eggs, to increase the carotenoid content in the egg yolk of Silkie chicken eggs, or to enhance the antioxidant activity of the egg yolk of Silkie chicken eggs. [Examples]

[0052] This embodiment will be specifically described below with reference to examples and comparative examples.

[0053] (Test Example 1) The effects of dietary carotenoids on egg yolk were investigated using laying hens. Forty 60-week-old Rhode Island Red chickens and 40 Silkie chickens ("Tokyo Ukokkei") were randomly divided into four groups, with two replicates of five chickens in each group. Each chicken was kept individually in an open-air cage for 28 days, and water and basal feed were provided freely.

[0054] • Control group (Cont): This group was fed only commercially available chicken feed (crude protein 17%, metabolizable energy 2800 kcal / kg, JA Higashi Nippon Kumiai Feed Co., Ltd.) as its basal feed. • Paprika extract group (PA): The basal feed was supplemented with a mixed feed containing powdered paprika extract (Runred®, Elanco Japan Co., Ltd.; carotenoid content: 5g / kg). The amount added was set to 30mg / kg of total carotenoids in the feed (2.5mg / kg of zeaxanthin). • Marigold Petal Extract Group (MA): The basal feed was supplemented with a mixed feed containing powdered marigold petal extract (Xan Yellow®, Elanco Japan Co., Ltd.; carotenoid content: 20 g / kg). The amount added was adjusted to provide 60 mg / kg of total carotenoids in the feed (36 mg / kg of lutein). • Paracoccus cell powder (AX): The basal feed was supplemented with a powdered astaxanthin-containing mixed feed (Panaferd®-P, ENEOS Corporation; carotenoid content: 35 g / kg) produced using Paracoccus bacteria. The amount added was set to 28 mg / kg of total carotenoids in the feed (16 mg / kg of astaxanthin).

[0055] Egg yolk, total carotenoid content in egg yolk, and singlet oxygen scavenging activity were measured using eggs from 22 to 28 days (4 weeks) after the start of the study.

[0056] (Method for measuring egg yolk color) Egg yolk color was measured using a spectrophotometer (CM-508b; Konica Minolta, Inc.) and its lightness (L) was measured on the CIELAB system. * Value), redness (a * Value), yellowness (b * The values ​​for yellowness and the ratio of redness to yellowness (a / b) were calculated. Egg yolk color was also measured using the Roche York Color Fan (RYCF) score.

[0057] (Method for measuring total carotenoid content and singlet oxygen scavenging activity) For the quantification of total carotenoids in egg yolk, eggs laid after a 4-week trial were used. After weighing the egg yolk, 15 mL of acetone was added to the yolk and stirred at room temperature (26 ± 2°C) for 15 minutes. The supernatant was collected, and 30 mL of dichloromethane-methanol (2:1, v / v) was added and the mixture was stirred at room temperature for 30 minutes to extract the carotenoids (this process was repeated three times). 100 mL of each extract was mixed with 100 mL of hexane and 100 mL of water, and the mixture was separated using a separatory funnel. The upper layer (yellow) was collected and dehydrated with anhydrous sodium sulfate, and the total carotenoid content was calculated using the optical density at λmax = 450-470 nm. For quantification, the following extinction coefficients and absorbances at 1% concentration were used: 2400 for the control group, 2072 for the PA group, 2500 for the MA group, and 2100 for the AX group (see Britton et al., Carotenoids Handbook, Birkhauser, 2004).

[0058] Next, to investigate the singlet oxygen scavenging activity, each extract obtained above was concentrated to dryness and subjected to silica gel column chromatography (Silica gel 60, Kanto Chemical Co., Ltd.; 10 mm id × 150 mm; solvent: hexane). Development was performed stepwise using hexane (50 mL), hexane-acetone 1:1 (40 mL), and acetone (50 mL). The eluents containing carotenoids in hexane-acetone (Fraction I) and acetone (Fraction II) were collected and concentrated to obtain a yellow oil.

[0059] Singlet oxygen scavenging activity was measured by the photo-oxidation reaction of linoleic acid using methylene blue as a sensitizer (see Kobayashi M and Sakamoto Y, Biotechnology Letters, 21: 265-269, 1999). To evaluate the carotenoid extract from egg yolk, 80 μL of 0.025 mM methylene blue-ethanol solution, 100 μL of 240 mM linoleic acid-ethanol solution, and 140 μL of ethanol with or without 40 μL of extract (total carotenoid solutions of 50 μM, 200 μM, and 400 μM in dichloromethane, resulting in final total carotenoid concentrations of 5 μM, 20 μM, and 40 μM, respectively) were placed in microglass vials (5.0 mL). The vials were tightly sealed with screw caps and septums, and the mixtures were irradiated in a cardboard box at 7000 lux at 22°C for 3 hours.

[0060] Next, the amount of conjugated linoleic acid produced was estimated by diluting 100 μL of the reaction mixture to 3.0 mL with ethanol and measuring the absorbance at 235 nm (see Hirayama et al., Lipids, 29: 149-150, 1994). The value for the case without carotenoid addition was determined, and the singlet oxygen scavenging activity was calculated based on this reference value. The activity was evaluated by the egg yolk concentration (μg / mL) that showed a 50% inhibitory effect on the production of conjugated linoleic acid from linoleic acid, and was expressed as the average of three experimental data. This indicates that a lower value indicates higher singlet oxygen scavenging activity.

[0061] (High-performance liquid chromatography (HPLC) analysis of carotenoids in egg yolk) The zeaxanthin, lutein, and astaxanthin content was analyzed using egg yolks laid after a 4-week trial. The analysis of zeaxanthin and lutein was performed as follows: First, each egg yolk sample (0.5 g) was mixed with 3% pyrogallol-ethanol solution (10 mL), 1% sodium chloride solution (0.5 mL), and 60% potassium hydroxide solution (1.0 mL), and the oils in the sample were saponified by stirring at 70°C for 30 minutes. Next, this mixture was cooled, and 1% sodium chloride solution (22.5 mL) and ethyl acetate-hexane (1:9, v / v; 15 mL) were added, followed by shaking for 5 minutes.

[0062] The upper layer of the solution was collected, and 15 mL of ethyl acetate-hexane (1:9, v / v) was added to the lower layer. The mixture was shaken for 5 minutes, and the upper layer was collected. This procedure was repeated twice. The extracted upper layers were mixed and concentrated to dryness to obtain a yellow oil. This yellow oil was dissolved in 10 mL of ethanol and filtered through a Millipore filter disc (Merck) with a pore size of 0.45 μm. 10 μL of the obtained solution was subjected to HPLC (1260 Infinity II LC system, Agilent) equipped with a photodiode array detector (1260 diode array detector HS, Agilent) for analyzing the carotenoid content. An Inertsil® ODS-3V column (GL Sciences; 4.6 mm id × 150 mm) was used, and the mixture was developed with 98% methanol at a flow rate of 0.5 mL / min at 40°C. Zeaxanthin and lutein were eluted with retention times (Rt) of 7.7 minutes and 6.8 minutes, respectively.

[0063] Astaxanthin analysis was performed as follows: 1.0 g of each egg yolk sample was dissolved in 1 mL of deionized water and 5 mL of acetone containing 1.2 mM butylated hydroxytoluene (BHT). 10 mL of acetone containing 1.2 mM BHT was added to the mixture, and after thorough stirring, the mixture was centrifuged at 3000 rpm for 10 minutes to collect the upper layer of the solution. Next, 5 mL of acetone containing 1.2 mM BHT was added to the lower layer and thoroughly stirred, and then 10 mL of acetone containing 1.2 mM BHT was added. The mixture was centrifuged at 3000 rpm for 10 minutes to collect the upper layer of the solution. The extracted upper layer was mixed, and 1.2 mM BHT-containing acetone was added to obtain 50 mL of solvent. This solvent was subjected to silica gel HPLC (COSMOSIL® Cholester, Nacalai Tesque; 4.6 mm id × 250 mm) at 35°C. A mixed solvent of acetone, deionized water, and tetrahydrofuran (770:215:15, v / v) was used as the mobile phase, and the sample was developed at a flow rate of 1.0 mL / min.

[0064] Astaxanthin was eluted at Rt values ​​of 13.9 min and 14.8 min. Carotenoid content was calculated using absorbance and calibration curves at 455 nm for zeaxanthin and lutein, and at 480 nm for astaxanthin.

[0065] (statistical analysis) Results were expressed as mean ± SE. Two-way ANOVA was performed on total carotenoid content in egg yolk, individual carotenoid content, egg yolk, and singlet oxygen scavenging activity to analyze the interaction between breed and feed. Tukey's method was used for multiple comparisons. All statistical analyses were performed using R software (http: / / www.R-project.org / ; Ihaka and Gentleman, 1996), with a significance level of P<0.05.

[0066] (result) Table 1 shows the values ​​for egg yolk. The feed showed a significant effect on all items (P<0.001). The breed was L * , b *And a significant effect was observed on the a / b value (P < 0.001). a * Regarding a and the a / b value, a significant interaction between breed and feed was observed. Furthermore, the addition of carotenoids increased the a * value and the RYCF score. That is, the a * value and the RYCF score of the treatment group were significantly higher than those of the control group (P < 0.05). Furthermore, the L * and b * values of silky fowl were higher than those of Rhode Island Red.

[0067]

Table 1

[0068] Figure 1 is a graph showing the total carotenoid content in egg yolk. Data are expressed as mean ± SE (n = 3). a~c There was a significant difference between different superscripts (P < 0.05). Cont = basal diet; PA = 30 mg / kg of carotenoids from paprika added to the basal diet; MA = 60 mg / kg of carotenoids from marigold flowers added to the basal diet; AX = 28 mg / kg of carotenoids from Paracoccus sp. powder added to the basal diet are represented respectively. RR = Rhode Island Red; SF = silky fowl are represented respectively.

[0069] The total carotenoid content in egg yolks was also higher in Silkie chickens than in Rhode Island Red chickens. Specifically, in Silkie chickens, the PA, MA, and AX groups accumulated significantly more carotenoids than the control group (P<0.05), but no significant difference was observed between the different treatment groups in Rhode Island Red eggs (Figure 1). Furthermore, eggs from the MA group of Silkie chickens contained more carotenoids than eggs from the PA and AX groups of Rhode Island Red chickens, and eggs from both control groups (P<0.05; Figure 1).

[0070] Figure 2 is a graph showing the content of (A) zeaxanthin, (B) lutein, and (C) astaxanthin in egg yolk. The data is expressed as mean ± SE (n=5). a~c There is a statistically significant difference between the different signs (P<0.05). Cont = basal feed; PA = basal feed supplemented with 30 mg / kg of paprika-derived carotenoids; MA = basal feed supplemented with 60 mg / kg of marigold petal-derived carotenoids; AX = basal feed supplemented with 28 mg / kg of Paracoccus cell powder-derived carotenoids. RR = Rhode Island Red; SF = Silkie chicken.

[0071] The zeaxanthin, lutein, and astaxanthin content in egg yolks increased in the PA, MA, and AX groups of both breeds, respectively (Figure 2). Zeaxanthin and lutein content in the PA and MA groups were significantly higher in Silkie chickens than in Rhode Island Red chickens (Figures 2(A) and (B); P<0.05). Conversely, no significant differences in astaxanthin content were observed between breeds.

[0072] Table 2 shows the effects of breed and feed on carotenoid content in egg yolk and singlet oxygen scavenging activity by egg yolk. The effect of feed was significant in total carotenoid content, zeaxanthin content, lutein content, astaxanthin content, and singlet oxygen scavenging activity (P<0.001). The effect of breed was significant in total carotenoid content, zeaxanthin content, lutein content, and singlet oxygen scavenging activity (P<0.001, P<0.01, P<0.001, and P<0.05, respectively). Furthermore, a significant interaction was shown between the effects of breed and feed on lutein content (P<0.01).

[0073] [Table 2] Breeds: Rhode Island Red, Silkie chicken. Feed = Basic feed, paprika extract, marigold petal extract, Paracoccus cell powder. *: P<0.05, **: P<0.01, ***: P<0.001, NS: No significant difference.

[0074] Figure 3 shows the singlet oxygen scavenging activity by egg yolk (50% inhibitory concentration; IC50). 50 This graph shows the data. The data is represented as mean ± SE (n=3). a~c There is a statistically significant difference between the different signs (P<0.05). Cont = basal feed; PA = basal feed supplemented with 30 mg / kg of paprika-derived carotenoids; MA = basal feed supplemented with 60 mg / kg of marigold petal-derived carotenoids; AX = basal feed supplemented with 28 mg / kg of Paracoccus cell powder-derived carotenoids. RR = Rhode Island Red; SF = Silkie chicken.

[0075] All treatment groups showed significantly different singlet oxygen scavenging activity compared to the Rhode Island Red control group (Figure 3; P<0.05). No significant differences were observed between treatment groups (Figure 3). The Silkie chicken AX group showed a significant difference compared to the control group (Figure 3; P<0.05).

[0076] Figure 4 is a graph showing the results of measuring egg yolk (RYCF score) every week. (A) shows the change in egg yolk over time for Rhode Island Red chickens, and (B) shows the change in egg yolk over time for Silkie chickens. The data is expressed as the mean value (n=12). Cont = basal feed; PA = basal feed supplemented with 30 mg / kg of paprika-derived carotenoids; MA = basal feed supplemented with 60 mg / kg of marigold petal-derived carotenoids; AX = basal feed supplemented with 28 mg / kg of Paracoccus cell powder-derived carotenoids.

[0077] In all treatment groups, egg yolk levels increased within one week of starting administration and then stabilized (Figure 4). A correlation is thought to exist between egg yolk levels and the amount of carotenoids (lutein, zeaxanthin, astaxanthin) in the egg yolk (Akiba Y, et al., Japanese poultry science, 37: 77-85. 2000; Islam KMS, et al., Journal of Poultry Science, 54: 271-277, 2017). Therefore, oral administration for at least 7 days is thought to exert a sufficient effect (enhancement of the amount transferred to the egg yolk and the antioxidant activity in the egg yolk).

[0078] (Consideration) This study investigated the effect of dietary carotenoids on egg quality in laying hens. Total carotenoid accumulation in the yolks of Silkie chickens was higher than that of Rhode Island Red chickens. This result suggests that dietary carotenoids are more likely to transfer to the yolks of Silkie chickens compared to those of Rhode Island Red chickens, a common laying hen. In particular, a significant interaction was observed between the effects of breed and feed on lutein content. This indicates that the combination of marigold petal extract-containing feed and Silkie chickens further promotes lutein accumulation in the yolks.

[0079] The supplementation of dietary carotenoids enhanced the singlet oxygen scavenging activity of egg yolks, and Silkie chickens accumulated more carotenoids in their egg yolks than the Rhode Island Red, a common laying hen. This was also observed in the control group. Furthermore, Paracoccus cell powder contains adonirubin and adonixanthin, which have high antioxidant capacity comparable to astaxanthin. Therefore, adonirubin and adonixanthin may also have influenced the singlet oxygen scavenging activity of the AX group.

[0080] RYCF score and a * The values ​​were significantly higher in the marigold petal extract group compared to the control group in both varieties (P<0.05). In the paprika extract group, the RYCF score and a * The values ​​and a / b values ​​were significantly higher (P<0.05), but L * The values ​​were lower in both varieties than in the control group. In both varieties, the RYCF score of the Paracoccus cell powder group was 14 or higher. In the Paracoccus cell powder group, a * The values ​​and a / b values ​​were also significantly higher, but L * The values ​​were lower than those of the control group. The RYCF score and a / b values ​​are used to evaluate the yolk color of the egg.

[0081] Therefore, these results indicate that dietary carotenoids have the effect of improving egg yolk color and enhancing the singlet oxygen scavenging activity of egg yolk. Furthermore, it was suggested that Silkie chickens are a particularly effective breed for improving egg quality using dietary carotenoids.

[0082] (Test Example 2) In this study, we investigated the effect of increasing the amount of dietary carotenoids given to laying hens on egg quality.

[0083] (method) Forty 55-week-old Silkie chickens (Tokyo Silkie) and 40 Rhode Island Red chickens (a common laying hen) were used in the experiment. The 40 chickens were randomly divided into four groups, with 5 chickens in each group for two replicates. The amount of carotenoids administered to each treatment group was twice that of Experiment 1.

[0084] • Control group (Cont): This group was fed only commercially available chicken feed (crude protein 17%, metabolizable energy 2800 kcal / kg, JA Higashi Nippon Kumiai Feed Co., Ltd.) as its basal feed. • Paprika extract group (PA): The basal feed was supplemented with a mixed feed containing powdered paprika extract (Runred®, Elanco Japan Co., Ltd.). The amount added was set to 60 mg / kg of total carotenoids in the feed (5.04 mg / kg of zeaxanthin). • Marigold Petal Extract Group (MA): The basal feed was supplemented with a mixed feed containing powdered marigold petal extract (Xan Yellow®, Elanco Japan Co., Ltd.). The amount added was set to 120 mg / kg of total carotenoids in the feed (71.40 mg / kg of lutein). • Paracoccus cell powder (AX): The basal feed was supplemented with a powdered astaxanthin-containing mixed feed (Panaferd®-P, ENEOS Corporation) produced using Paracoccus bacteria. The amount added was set to 56 mg / kg of total carotenoids in the feed (31.04 mg / kg of astaxanthin).

[0085] The test period was four weeks, and the rearing method was the same as in Test Example 1, except for the amount of carotenoid supplementation. The body weight of the test chickens was measured on the start and end of the test, and the amount of remaining feed was measured every seven days. The weight of all eggs laid during the test period was measured, and the egg quality was examined every seven days. The amounts of zeaxanthin, lutein, and astaxanthin in the egg yolk were measured by HPLC. Singlet oxygen scavenging activity was evaluated by the egg yolk concentration that showed a 50% inhibitory effect on the development of conjugated linoleic acid generated from linoleic acid. A lower value indicates higher singlet oxygen scavenging activity. The above measurement methods and statistical analysis were performed in the same manner as in Test Example 1.

[0086] (result) Table 3 shows the comparison results for egg yolk. Two-way ANOVA showed that the feed had an effect on all parameters in egg yolk. * Value (brightness), b* The effects of breed were observed in the values ​​(yellowness) and a / b (an objective indicator said to accurately reflect the color of the egg yolk). Furthermore, since an interaction was observed in a / b, it was suggested that there are not only differences in carotenoid accumulation among chicken breeds, but also effects due to the combination of breed and feed (interaction) (Table 3).

[0087] [Table 3] The data is expressed as mean ± SE (n=10). a~e Significant differences were observed between different signs in the same column (P<0.05), ***: P<0.001, NS: no significant difference. L * =brightness;a * = redness; b * =Yellowness; RYCF score = Roche York Color Fan score (1-15). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; PA = Paprika extract; MA = Marigold petal extract; AX = Paracoccus cell powder.

[0088] Figure 5 is a graph showing the content of (A) zeaxanthin, (B) lutein, and (C) astaxanthin in egg yolk. The data is expressed as mean ± SE (n=4). a~c There is a statistically significant difference between different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = basal feed; PA = basal feed supplemented with 60 mg / kg of paprika-derived carotenoids; MA = basal feed supplemented with 120 mg / kg of marigold petal-derived carotenoids; AX = basal feed supplemented with 56 mg / kg of Paracoccus cell powder-derived carotenoids.

[0089] In terms of carotenoid transfer to egg yolk, all three experimental groups showed greater transfer than the control group, and in two experimental groups (PA and MA), Silkie chickens showed greater transfer than Rhode Island Red (generic chicken). In the Silkie chicken PA group, the egg yolk contained 1 mg / 100g or more of zeaxanthin. In addition, the Silkie chicken MA group contained 4 mg / 100g or more of lutein (Figure 5).

[0090] Table 4 shows the effects of breed and feed on carotenoid content in egg yolk and singlet oxygen scavenging activity by egg yolk. Two-way ANOVA revealed no significant differences in total carotenoid content in egg yolk, similar to those observed in Test Example 1, suggesting an upper limit for carotenoid supplementation in feed. Differences in zeaxanthin and lutein were observed not only due to feed but also to breed. In particular, lutein showed an effect due to the combination of breed and feed (interaction), demonstrating a synergistic effect of carotenoid (lutein) supplementation in Silkie chickens. Furthermore, the observation of a combination of breed and feed (interaction) in singlet oxygen scavenging activity, in addition to the effect of feed and breed, also indicates the superiority of Silkie chickens (Table 4).

[0091] [Table 4] Breeds: Rhode Island Red, Silkie chicken. Feed = Basic feed, paprika extract, marigold petal extract, Paracoccus cell powder. †: P<0.1, *: P<0.05, **: P<0.01, ***: P<0.001, NS: No significant difference.

[0092] Figure 6 shows the singlet oxygen scavenging activity by egg yolk (50% inhibitory concentration; IC50). 50 This is a graph showing the mean ± SE. The data is represented as mean ± SE (n=3). a~dThere is a statistically significant difference between different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = basal feed; PA = basal feed supplemented with 60 mg / kg of paprika-derived carotenoids; MA = basal feed supplemented with 120 mg / kg of marigold petal-derived carotenoids; AX = basal feed supplemented with 56 mg / kg of Paracoccus cell powder-derived carotenoids.

[0093] The singlet oxygen scavenging activity of egg yolk was higher in the treated group than in the control group (Figure 6). This demonstrated that the added value of Silkie chicken eggs can be increased by supplementing with carotenoids.

[0094] Table 5 shows the egg-laying rate, egg weight, feed intake, and feed conversion ratio. For Silkie chickens, egg weight increased significantly in all treatment groups, and egg-laying rate and feed intake increased significantly in the PA group (P<0.05, Table 5).

[0095] [Table 5] The data is expressed as mean ± SE (n=10). a~c There is a significant difference between different signs in the same column (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; PA = Paprika extract; MA = Marigold petal extract; AX = Paracoccus cell powder.

[0096] (Consideration) Based on the results of this study (such as the transfer of zeaxanthin and lutein to egg yolk and the enhancement of singlet oxygen scavenging activity), it was found that the upper limit for carotenoid intake (the amount beyond which further increases in the concentration of carotenoids in the feed do not lead to parallel improvements in performance and the unique advantages of Silkie chickens are considered to decrease) is 60 mg / kg of total carotenoids from paprika (5.04 mg / kg as zeaxanthin), 120 mg / kg of total carotenoids from marigold petals (71.40 mg / kg as lutein), and 56 mg / kg of total carotenoids from Paracoccus cell powder (31.04 mg / kg as astaxanthin).

[0097] Furthermore, the daily intake of each carotenoid per chicken (the amount actually consumed by the chicken) was 0.32 mg (PA) for zeaxanthin, 4.21 mg (MA) for lutein, and 1.83 mg (AX) for astaxanthin in Silkie chickens. In Rhode Island Red chickens (general chickens), the intake was 0.57 mg (PA) for zeaxanthin, 7.98 mg (MA) for lutein, and 3.55 mg (AX) for astaxanthin.

[0098] (Test Example 3) This study investigated the effect of supplemental feeding of dietary carotenoids on egg quality in laying hens.

[0099] (method) Thirty 60-week-old Silkie chickens (Tokyo Silkie) and 30 Rhode Island Red laying hens were used in the experiment. The 30 chickens were randomly divided into the following three groups. The control group was fed only basal feed. In the test groups, two types each of marigold petal extract ((registered trademark), Elanco Japan Co., Ltd., MA), paprika extract (Lanred (registered trademark), Elanco Japan Co., Ltd., PA), and Paracoccus cell powder (Panaferd (registered trademark)-P, ENEOS Corporation, AX) were added to the basal feed to investigate the effects of concomitant carotenoid supplementation. The amount of MA, PA, and AX given was set to 0.5, with the amount of carotenoid supplementation in Test Example 1 set to 1.

[0100] • Control group (Cont): Only basal feed (commercially available chicken feed; crude protein 17%, metabolizable energy 2800 kcal / kg; JA Higashi Nippon Kumiai Feed Co., Ltd.) was given. • MA+PA group: Marigold petal extract was added to the basal feed at a concentration of 30 mg / kg as total carotenoids (17.85 mg / kg as lutein), and paprika extract was added at a concentration of 15 mg / kg as total carotenoids (1.26 mg / kg as zeaxanthin), and both were administered concurrently. • MA+AX group: Marigold petal extract was added to the basal feed at a total carotenoid concentration of 30 mg / kg (17.85 mg / kg as lutein), and astaxanthin-containing mixed feed produced using Paracoccus bacteria was added at a total carotenoid concentration of 14 mg / kg (7.76 mg / kg astaxanthin), and these were fed in combination.

[0101] The test period was four weeks, and the rearing method was the same as in Test Example 1, except for the amount of carotenoid supplementation. The body weight of the test chickens was measured on the start and end of the test, and the amount of remaining feed was measured every seven days. The weight of all eggs laid during the test period was measured, and the egg quality was examined every seven days. The amounts of zeaxanthin, lutein, and astaxanthin in the egg yolk were measured by HPLC. Singlet oxygen scavenging activity was evaluated by the egg yolk concentration that showed a 50% inhibitory effect on the development of conjugated linoleic acid generated from linoleic acid. A lower value indicates higher singlet oxygen scavenging activity. The above measurement methods and statistical analysis were performed in the same manner as in Test Example 1.

[0102] (result) Table 6 shows the comparison results for egg yolk. Two-way ANOVA showed that the effect of the feed was observed in all items. * Value (brightness), a * Value (redness) and b * The effects of breed were observed in the values. The effect of breed on egg yolk suggests differences in the ability of breeds to transfer carotenoids to egg yolk. No interaction effect on egg yolk was observed between breed and feed combinations in combined feeding (Table 6).

[0103] [Table 6] The data is expressed as mean ± SE (n=6). a~c Significant differences were observed between different signs in the same column (P<0.05): †: P<0.1, *: P<0.05, ***: P<0.001, NS: No significant difference. L * =brightness;a * = redness; b * =Yellowness; RYCF score = Roche York Color Fan score (1-15). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; PA = Paprika extract; MA = Marigold petal extract; AX = Paracoccus cell powder.

[0104] Figure 7 is a graph showing the (A) lutein, (B) zeaxanthin, and (C) astaxanthin content in egg yolk. The data is expressed as mean ± SE (n=5). a~c There is a statistically significant difference between different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; MA+PA = Basic feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 15 mg / kg of carotenoids derived from paprika; MA+AX = Basic feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 14 mg / kg of carotenoids derived from Paracoccus bacteria powder.

[0105] In terms of the content of each carotenoid in egg yolk, Silkie chickens showed higher values ​​than general chickens, with the exception of astaxanthin. In all Silkie chicken treatment groups, the egg yolks contained at least 1 mg / 100g of zeaxanthin and at least 4 mg / 100g of lutein (Figure 7).

[0106] Table 7 shows the effects of breed and feed on carotenoid content in egg yolk and singlet oxygen scavenging activity by egg yolk. Two-way ANOVA revealed significant differences between breed and feed for all parameters. In particular, significant differences were observed in total carotenoid content by breed, similar to the results in Test Example 1 (P<0.01). Significant differences were also observed in zeaxanthin and lutein by breed (P<0.001). Furthermore, the significant difference observed in singlet oxygen scavenging activity by breed (P<0.001) also indicates the superiority of the Silkie chicken (Table 7).

[0107] [Table 7] Breeds: Rhode Island Red, Silkie chicken. Feed = Basic feed, marigold petal extract + paprika extract, marigold petal extract + Paracoccus bacteria powder. *: P<0.05, **: P<0.01, ***: P<0.001, NS: No significant difference.

[0108] Figure 8 shows the singlet oxygen scavenging activity by egg yolk (50% inhibitory concentration; IC50). 50 This is a graph showing the mean ± SE. The data is represented as mean ± SE (n=3). a~c There is a statistically significant difference between different signs within the same graph (P<0.05). RR = Rhode Island Red; SF = Silkie chicken. Cont = Basic feed; MA+PA = Basic feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 15 mg / kg of carotenoids derived from paprika; MA+AX = Basic feed supplemented with 30 mg / kg of carotenoids derived from marigold petals and 14 mg / kg of carotenoids derived from Paracoccus bacteria powder.

[0109] The singlet oxygen scavenging activity of egg yolk was increased in the treated group compared to the control group. Furthermore, the egg yolk of Silkie chickens showed higher reactive oxygen species scavenging activity compared to that of general chickens. In all Silkie chicken treated groups, IC50 was higher than that of the general chicken control group. 50 The value was less than half, and therefore the singlet oxygen scavenging activity of Silkie chicken eggs was more than twice that of regular chicken eggs (Figure 8).

[0110] (Consideration) In this study, the results of combined carotenoid feeding showed the same superiority of Silkie chickens as in Study 1, in terms of the transfer of carotenoids (lutein and zeaxanthin) to egg yolk and the singlet oxygen scavenging activity of egg yolk. Combined carotenoid feeding was performed by combining two of the following amounts in the feed: zeaxanthin at 1.26 mg / kg (PA), lutein at 17.85 mg / kg (MA), and astaxanthin at 7.76 mg / kg (AX). The daily intake of each carotenoid per chicken (the amount actually consumed by the chicken) was 1.08 mg of lutein and 0.08 mg of zeaxanthin for Silkie chickens in the MA+PA regimen, and 1.01 mg of lutein and 0.44 mg of astaxanthin for the MA+AX regimen. In Rhode Island Red (common chicken), MA+PA contained 1.82mg of lutein and 0.13mg of zeaxanthin, while MA+AX contained 1.90mg of lutein and 0.82mg of astaxanthin.

[0111] In this study, the amount of paprika-derived carotenoids added to the basal feed was 15 mg / kg, which was 1 / 2 and 1 / 4 of that in study examples 1 and 2, respectively. Nevertheless, the amount of zeaxanthin transferred to the egg yolk of Silkie chickens was 1.25 mg / 100g egg yolk, which was significantly higher than in both the Cont and general chicken study groups (Figure 7(B)). To achieve Silkie chicken eggs with a zeaxanthin content of 1.0 mg / 100g egg yolk or higher, it was estimated that the amount of paprika-derived carotenoids added to the basal feed should be less than that in this study, around 8.5 mg / kg or more.

[0112] Furthermore, regarding lutein, even though the amount of marigold petal-derived carotenoids added to the basal feed in this study was 30 mg / kg, which was 1 / 2 and 1 / 4 of that in study examples 1 and 2, respectively, the amount of lutein transferred to the egg yolk of Silkie chickens was 4.64 mg / 100g egg yolk, which was significantly higher than that of Cont (Figure 7(A)). It was estimated that in order to achieve Silkie chicken eggs with a lutein content of 4.0 mg / 100g egg yolk or higher, the amount of marigold petal-derived carotenoids added to the basal feed should be less than that in this study, around 24.4 mg / kg or more. [Industrial applicability]

[0113] This invention has shown that feeding laying hens a diet rich in carotenoids improves the color of the egg yolk and enhances its antioxidant activity. In particular, it was found that Silkie chickens accumulate more carotenoids (lutein and zeaxanthin) in their egg yolks than ordinary chickens. Therefore, Silkie chickens are considered a suitable breed for improving egg quality by adding carotenoids to their feed. Accordingly, this invention is expected to expand the use of Silkie chicken eggs and contribute to the food or health food industry.

Claims

1. A method for improving the quality of Silkie chicken eggs, characterized by orally feeding Silkie chickens a feed containing 8.5 mg / kg or more of paprika-derived carotenoids and / or 24.4 mg / kg or more of marigold petal-derived carotenoids for at least 7 days.

2. The method according to claim 1, which allows for obtaining a Silkie chicken egg having a zeaxanthin content of 1 mg / 100 g egg yolk or more, and / or a luten content of 4 mg / 100 g egg yolk or more.

3. The method according to claim 1 or 2, wherein the Silkie chicken is a Tokyo Silkie chicken.

4. A feed for Silkie chickens, characterized by containing 8.5 mg / kg or more of carotenoids derived from paprika and / or 24.4 mg / kg or more of carotenoids derived from marigold petals.

5. The feed according to claim 4, which is for enhancing the antioxidant activity of egg yolk.

6. A method for producing feed for Silkie chickens, characterized by incorporating 8.5 mg / kg or more of paprika-derived carotenoids and / or 24.4 mg / kg or more of marigold petal-derived carotenoids into the feed.

7. The manufacturing method according to claim 6, wherein the feed for Silkie chickens is for enhancing the antioxidant activity of egg yolks.

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