Method for increasing content of glutathione in egg yolk

Abstract

The invention relates to a method for increasing the content of glutathione in egg yolk. According to the present invention, by using the effect that cysteine can combine glutamic acid and glycine in animal bodies so as to synthesize glutathione, the artificially synthesized N-acetylcysteine is added to the laying fowl feed, and the laying fowls are fed for 4 weeks, such that the glutathione content in the egg yolk is significantly increased, and can be up to 1.44 times of the glutathione content in the egg yolk of the common poultry egg, such that the glutathione content in the egg yolk can be significantly improved; and the nutritional value and the economic value of the poultry eggs are improved.

Description

Technical Field

[0001] The invention relates to the field of egg-laying poultry feed, in particular to a method for increasing the glutathione content in egg yolks of poultry. Background Art

[0002] Glutathione (GSH) is a tripeptide composed of glutamic acid, cysteine ​​and glycine. As an antioxidant, it participates in the redox reaction in cells and has antioxidant and integrated detoxification effects. However, factors such as aging and disease can cause a decrease in glutathione levels in animals, impair liver function, lead to toxin accumulation, and cause cell and organ damage.

[0003] Glutathione can be synthesized by three amino acids through endogenous pathways in the human body, or it can be obtained through exogenous food intake. For example, asparagus, avocado, okra, etc. are rich in glutathione. Studies have found that a diet supplemented with 9% egg white increases the content of glutathione in heart tissue, which has effective antioxidant and mild anti-inflammatory effects. Egg white is mainly composed of water (about 90%) and protein (such as ovalbumin, ovotransferrin, etc.), with a low glutathione content, and its antioxidant function actually depends more on other components. Although glutathione has a powerful effect, it also has the disadvantages of being easily oxidized and having poor stability. Due to the cooking process of food and the degradation of glutathione by γ-glutamyl transpeptidase in the intestine, the absorption and utilization of oral glutathione is low. Therefore, it is more efficient to directly ingest glutathione precursors such as cysteine, and let it combine with glutamate and glycine in the body to form glutathione.

[0004] N-Acetylcysteine ​​(NAC) is found in allium plants such as shallots and garlic. It is an N-acetyl derivative of cysteine ​​and has antioxidant, anti-inflammatory and lipid metabolism regulating effects. Chemically, N-acetylcysteine ​​is similar to cysteine, but the presence of acetyl groups reduces the reactivity of thiols compared to cysteine. Therefore, N-acetylcysteine ​​is less toxic, less susceptible to oxidation and dimerization, and more soluble in water, making it a better source of cysteine ​​than parenteral cysteine ​​itself. There are also studies that use specific fluorescent probes designed through substitution-rearrangement mechanisms to distinguish cysteine ​​from other thiols. After using this probe, it was found that N-acetylcysteine ​​is superior to cysteine ​​to supplement intracellular cysteine. It has been found that supplementing N-acetylcysteine ​​can effectively increase glutathione levels in whole blood.

[0005] Studies have found that adding an appropriate dose of N-acetylcysteine ​​to laying fowl feed can increase the content of glutathione in serum and the activity of antioxidant enzymes such as glutathione peroxidase, thereby improving the overall antioxidant performance of laying fowl; at the same time, adding N-acetylcysteine ​​can also improve indicators such as egg protein height and Haugh units, making the protein more viscous, more active protein, and higher freshness of the eggs, thereby extending the shelf life of the eggs, delaying the occurrence of adverse consequences such as the decrease in vitamin and unsaturated fatty acid content, destruction and loss of nutrients in long-term stored eggs due to oxidation, and stabilizing the breeding profits of poultry egg companies.

[0006] However, as mentioned above, the glutathione content of egg white is generally low, and there is no research report directly showing that the ingestion of cysteine ​​by laying poultry can promote the synthesis of glutathione and increase its deposition in the yolk, the main nutrient carrier of eggs. Therefore, it is particularly urgent to seek a simple and effective method to increase the glutathione content in egg yolk and improve the antioxidant properties of eggs, so as to achieve the purpose of improving the nutritional value of eggs and the added value of related products; this has important application value and production practice significance for improving the economic benefits of laying hen farming and promoting the healthy development of the poultry industry. Summary of the invention

[0007] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for increasing the glutathione content in egg yolks. The method uses the method of feed nutrition regulation to utilize the effect of ingested N-acetylcysteine ​​and glycine and glutamate in the body of laying fowl to synthesize glutathione, so as to achieve the purpose of increasing the glutathione content in egg yolks and improving the antioxidant properties of eggs; the method can improve the nutritional value and added value of eggs, and help to improve the economic benefits of laying fowl breeding.

[0008] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0009] A method for increasing the glutathione content in egg yolks of poultry, characterized in that the method comprises: adding N-acetylcysteine ​​to laying poultry feed, and using the laying poultry feed to feed laying poultry.

[0010] On the basis of the above scheme,

[0011] The added amount of the N-acetylcysteine ​​is 0.01-0.5wt%.

[0012] On the basis of the above scheme,

[0013] The added amount of the N-acetylcysteine ​​is 0.05-0.2 wt %.

[0014] On the basis of the above scheme,

[0015] The added amount of the N-acetylcysteine ​​is 0.08-0.1 wt %.

[0016] The feeding scheme is that the laying hens are fed with common feed containing a certain weight percentage of N-acetylcysteine ​​as described in the above technical scheme, and are directly fed into the feed trough twice or more a day for 4 weeks. During the feeding process, the laying hens are free to eat and drink, and are routinely managed and immunized. The feeding management method and feed preparation of laying poultry suggested by the present invention can be determined according to relevant national laws and regulations and feeding standards.

[0017] A laying fowl feed, characterized in that the laying fowl feed contains 0.1wt% of N-acetylcysteine.

[0018] On the basis of the above scheme,

[0019] The laying fowl feed contains 0.01-0.5wt% of N-acetylcysteine.

[0020] On the basis of the above scheme,

[0021] The laying fowl feed contains 0.05-0.2wt% of N-acetylcysteine.

[0022] On the basis of the above scheme,

[0023] The laying fowl feed contains 0.08-0.1wt% of N-acetylcysteine.

[0024] The method for increasing the glutathione content in egg yolks of the present invention has the following beneficial effects:

[0025] 1. The new laying poultry feed of the present invention is used to feed laying poultry, which greatly increases the content of glutathione in the egg yolk, which can reach 1.44 times the content of glutathione in the egg yolk of ordinary poultry eggs (chicken eggs).

[0026] 2. To avoid the inactivation of glutathione after being digested by directly adding glutathione to the diet, the method of the present invention utilizes the principle of synthesizing glutathione by taking in N-acetylcysteine, glycine and glutamic acid, so as to increase the deposition amount of glutathione in eggs.

[0027] 3. Compared with directly adding cysteine ​​to the diet, N-acetylcysteine ​​is less toxic and less susceptible to oxidation and dimerization, making it a better source of cysteine.

[0028] 4. The novel laying poultry feed of the present invention is used to feed laying poultry, which improves the quality of eggs and also improves the antioxidant performance of laying poultry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention has the following accompanying drawings:

[0030] Figure 1 Comparison of egg white and yolk after four weeks of feeding for laying fowl: the NAC group was supplemented with 0.1wt% N-acetylcysteine, and the CON group was not supplemented with N-acetylcysteine. DETAILED DESCRIPTION

[0031] The present invention is described below by specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be understood as illustrative rather than limiting the scope of the present invention, and the essence and scope of the present invention are limited only by the claims. For those skilled in the art, various changes or modifications to the material composition and dosage in these embodiments, without departing from the essence and scope of the present invention, also belong to the protection scope of the present invention. The raw materials and reagents used in the present invention are all commercially available, such as N-acetylcysteine.

[0032] Example 1 Validation test of the method for increasing the glutathione content in egg yolk

[0033] (1) Animal and grouping

[0034] In this example, 192 laying hens in the late egg-laying period were selected for the experiment and randomly divided into a control group and an experimental group, with 4 replicates in each group and 24 laying hens in each replicate.

[0035] (2) Diet and feeding management

[0036] The control group was fed a basal diet (the formula and some nutrient content are shown in Tables 1 and 2, respectively), and the nutritional requirements of laying hens were proportioned according to the NRC and my country's chicken feeding standards; the experimental group added 1% N-acetylcysteine ​​to the basal diet; the laying hens in each group were caged and had free access to food and water during the experiment; each group was fed a basal diet for a pre-test of 1 week, and then began to feed the corresponding experimental diet, and the experimental period was 4 weeks.

[0037] Table 1 Basic diet formula

[0038]

[0039]

[0040] Note: 1) Trace element premix 1 provides per kilogram of feed: iron (ferrous sulfate) 20mg, manganese (manganese sulfate) 100mg, copper (copper sulfate) 8mg, zinc (zinc sulfate) 75mg, selenium (sodium strontite) 0.15mg, iodine (potassium iodide) 0.35mg. 2) Vitamin premix 1 provides per kilogram of feed: V A 12500IU,V B1 2mg, V B2 6mg, VB12 0.025mg, V D3 2500IU,V E 30IU,V K3 2.65mg, biotin 0.0325mg, folic acid 1.25mg, niacin 50mg, nicotinic acid 12mg.

[0041] Table 2 Content of some nutrients in the basic diet

[0042]

[0043]

[0044] (3) Sample collection and index determination

[0045] At the end of the 4th week of the experiment, 25 eggs were randomly selected from each group for egg quality determination, and 6 egg yolks were randomly selected from each group for determination of glutathione and malondialdehyde content, total antioxidant capacity, superoxide dismutase and catalase activity. The glutathione content of egg yolk was determined by microplate method.

[0046] (4) Experimental results

[0047] First, by Figure 1 It can be seen that the degree of yolk bulge in the NAC group was significantly higher than that in the control group. At the same time, the protein viscosity of the NAC group also showed a higher density and lower transparency than that of the chicken control group.

[0048] Second, adding 1% N-acetylcysteine ​​to laying hen diets had no significant effect on eggshell thickness, yolk color, yolk weight, and eggshell strength, but significantly increased albumen height and Haugh unit (P<0.05) (Table 3), indicating that it had a certain improvement effect on egg quality.

[0049] Table 3 Effect of dietary supplementation with 0.1% N-acetylcysteine ​​on egg quality

[0050]

[0051] Data in the same row without letters indicate no significant difference (P>0.05), and different lowercase letters indicate significant difference (P<0.05).

[0052] Third, by measuring the glutathione content in egg yolk and egg white, it was found that the glutathione content in the egg yolk of the control group was 5.216 μmol / g prot, while the glutathione content in the egg yolk of the experimental group was 7.539 μmol / g prot, an increase of 1.44 times. However, there was no significant difference in the glutathione content in the egg white between the two groups. Considering the production performance of laying hens, egg quality and glutathione content in egg yolk, adding 0.1% N-acetylcysteine ​​to conventional laying hen feed can significantly increase the glutathione content in egg yolk (P < 0.05), while the increase in glutathione content in egg white is not significant (Table 4).

[0053] Table 4 Effect of dietary supplementation with 0.1% N-acetylcysteine ​​on glutathione content in egg yolk and egg white

[0054]

[0055] Fourth, the test found that adding 0.1% N-acetylcysteine ​​to the laying hen diet significantly increased the total antioxidant capacity of egg yolk and the enzyme activity level of catalase (P < 0.05) (Table 5), and improved the overall antioxidant properties of eggs.

[0056] Table 5 Effect of dietary supplementation with 0.1% N-acetylcysteine ​​on the antioxidant properties of eggs

[0057]

[0058] Fifth, adding 1% N-acetylcysteine ​​to the laying hen feed had a significant effect on the antioxidant level of laying hen serum, significantly increasing the levels of CAT (P < 0.05) and GSH-PX (P < 0.05) in the laying hen serum, and significantly reducing the level of MDA (P < 0.05) (Table 6), thereby improving the overall antioxidant performance of laying hens.

[0059] Table 6 Effect of dietary supplementation with 0.1% N-acetylcysteine ​​on the antioxidant properties of eggs

[0060]

[0061] Sixth, adding 1% N-acetylcysteine ​​to the laying hen diet had no significant effect on the average egg production rate and feed-egg ratio from 1 to 4 weeks (P>0.05), but compared with the initial average egg weight, it increased the average egg weight from 1 to 4 weeks (Table 7), improving the overall egg-laying performance of laying hens.

[0062] Table 7 Effect of dietary supplementation with 0.1% N-acetylcysteine ​​on laying performance of laying hens

[0063]

[0064] Seventh, adding 1% N-acetylcysteine to the diet of breeding hens had no significant effect on the hatching rate of hatching eggs, but significantly increased the fertilization rate (P<0.05), and there was a tendency to increase the weight of newly hatched chicks (0.05<P<0.1), improving the hatching performance of the hatching eggs produced by breeding hens.

[0065] Table 8 Effects of adding 0.1% N-acetylcysteine to the diet of breeding hens on the hatching performance of hatching eggs

[0066]

[0067] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

[0068] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A method for increasing the glutathione content in egg yolk, characterized in that: The method comprises the following steps: adding N-acetylcysteine ​​to laying fowl feed, and using the laying fowl feed to feed laying fowl.

2. The method according to claim 1, characterized in that: The added amount of the N-acetylcysteine ​​is 0.01-0.5wt%.

3. The method according to claim 2, characterized in that: The added amount of the N-acetylcysteine ​​is 0.05-0.2 wt %.

4. The method according to claim 2, characterized in that: The added amount of the N-acetylcysteine ​​is 0.08-0.1 wt %.

5. A laying fowl feed, characterized in that: The laying fowl feed contains 0.01-0.5wt% of N-acetylcysteine.

6. A laying fowl feed as claimed in claim 5, characterized in that: The laying fowl feed contains 0.05-0.2wt% of N-acetylcysteine.

7. A laying fowl feed as claimed in claim 6, characterized in that: The laying fowl feed contains 0.08-0.1wt% of N-acetylcysteine.

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