Patent Application
20230255239
This patent application claims the benefit and priority of Chinese Patent Application No. 202210132097.6, filed with the China National Intellectual Property Administration on Feb. 14, 2022, the disclosure of which is incorporated by reference herein in its entirety as part of the present application.
The present disclosure belongs to the field of aquatic animal nutritional feeds, and particularly relates to a feed additive for improving intestinal structure of Larimichthys crocea, a feed and use.
L. crocea belongs to the genus Larimichthys of the family Sciaenidae of the order Perciformes of the class Osteichthyes. L. crocea is mainly distributed in the Southeast China Sea area. Its meat is delicious and has certain medicinal value. It is a unique marine economic fish in China. According to the 2021 China Fishery Statistical Yearbook, the aquaculture production of L. crocea exceeded 250,000 tons, making it the largest marine economic fish in China.
With the rapid development of China's aquaculture industry in recent years, the demand for high-quality fat source for fish feed, fish oil, is expanding, and the supply-demand relationship of fish oil is gradually unbalanced. Seeking for alternatives to fish oil has become a hotspot in the marine fish aquaculture feed industry. Vegetable oils such as soybean oil and palm oil are widely used in the aquaculture of marine fish like L. crocea due to their low prices, wide sources and rich fatty acid content. However, it is found in actual production that the use of a high proportion of vegetable oil often leads to adverse effects including damage to the intestinal barrier of fish, reduction of intestinal villi, changes in intestinal structure and decrease of antioxidant capacity, which damages the health of fish and restricts the development of intensive mariculture. Therefore, it is urgent to find specific regulatory means to solve the problem of intestinal damage caused by replacement of high proportion of vegetable oil.
Glyceryl monolaurate is a monoglyceride derivative of lauric acid, which is widely used in aquaculture because of its excellent antibacterial and antiviral abilities and growth-promoting function. According to previous findings, adding a certain proportion of glyceryl monolaurate in the breeding feed of Lateolabrax maculatus can reduce abdominal fat deposition; using glyceryl monolaurate in the breeding of white shrimp can improve digestive enzyme activity and non-specific immune response and promote growth. However, it is not clear whether glyceryl monolaurate has an alleviating effect on intestinal structure repair and intestinal damage in aquatic animals.
The problem to be solved by the present disclosure is to provide a feed additive for improving intestinal structure of L. crocea, a feed and use. By adding a specific proportion of glyceryl monolaurate in the feed, intestinal barrier damage, reduced intestinal villi, and decreased antioxidant activity in L. crocea can be changed, which is expected to solve the technical barriers in the process of oil source substitution in the aquaculture industry.
The present disclosure is achieved by the following technical solutions:
A feed additive for improving intestinal structure of L. crocea is provided, and the feed additive includes glyceryl monolaurate.
The present disclosure further provides a feed containing the feed additive, and a mass percentage of the glyceryl monolaurate in the feed is 0.04%.
The present disclosure further provides use of the feed in improving the intestinal structure of the L. crocea, and the use lasts for at least 70 days.
Compared with the prior art, the present disclosure has the following beneficial effects:
1) The feed additive and the feed provided by the present disclosure can effectively improve intestinal morphological change, reduced intestinal villi, and intestinal barrier damage caused by replacement of fish oil with soybean oil.
2) The feed additive and the feed provided by the present disclosure can effectively relieve damage of intestinal antioxidant activity caused by replacement of fish oil with soybean oil (increased antioxidant enzyme activity and decreased malondialdehyde (MDA) content).
3) The glyceryl monolaurate provided by the present disclosure is a nutrient required by fish, has no toxic and side effects, and has no influence on food safety.
In order to illustrate the specific implementations of the present disclosure or the technical solutions in the prior art more clearly, the accompanying drawings that need to be used in the description of the specific implementations or the prior art will be briefly described below. Apparently, the accompanying drawings in the following description are some implementations of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.
The technical features of the present disclosure will be further explained below through the examples, but the protection scope of the present disclosure is not limited in any form by the examples.
1. Experimental Design and Experimental Feed Formula
Based on the soybean oil diet formula for L. crocea used in the laboratory in previous years, glycerol monolaurate with different mass percentages of 0.02%, 0.04%, and 0.08% (namely 200 mg/kg, 400 mg/kg, and 800 mg/kg) were supplemented, respectively. In addition, a conventional fish oil feed group was used as a negative control group. The feed formula is shown in Table 1.
1White fish meal (74% CP and 12.6% EE); premium krill meal (53.18% CP and 13% EE); dehulled soybean meal (46.68% CP and 0.33% EE); and strong flour (19.66% CP and 0.98% EE).
2Compound vitamin premix (mg/kg diet) (retinyl acetate, 3; vitamin D, 35; alpha-tocopherol, 240; vitamin K, 240; vitamin B1, 25; vitamin B2, 45; pyridoxine hydrochloride, 20; vitamin B12, 10; pantothenic acid, 60; folic acid, 20; nicotinic acid, 200; biotin, 60; inositol, 800; and MCC, 13473)
3Compound mineral premix (mg/kg diet) (magnesium sulfate, 1200; copper sulfate, 10; ferrous sulfate, 80; zinc sulfate, 50; manganese sulfate, 45; cobalt chloride, 50; sodium selenite, 20; calcium iodate, 60; and zeolite powder, 13485;)
4Glycine and betaine.
5Glycerol monolaurate: 92% pure.
2. Experimental Fish and Aquaculture Management
In this experiment, a total of 540 experimental L. crocea juveniles with an initial body weight of 13 g were selected, and the fry were purchased from Ningde Fufa Fisheries Co., Ltd., Fujian Province. The fry were randomly divided into three groups with three replicates of 60 fish fry, and the aquaculture period was 10 weeks. After the formal experiment started, the fry were fed heavily at 5:00 a.m. and 17:00 p.m. every day, the surface debris was cleaned up, and dead fish were removed at irregular intervals. During the experiment, the water temperature was maintained at 19.3-22.8° C., the salinity was at 25.6-29.9‰, and the dissolved oxygen level was 6.1-7.0 mg/L.
3. Collection and Analysis of Experimental Samples
At the end of the aquaculture experiment, sampling was performed 24 h after fasting. After the experimental fish was anesthetized, the intestines were quickly dissected out and stored in liquid nitrogen for subsequent analysis of intestinal barrier-related gene expression and antioxidant enzyme activity. Another three juveniles were taken to obtain the hindgut, which was rinsed with phosphate-buffered saline (PBS) and then fixed in paraformaldehyde for paraffin section preparation. Intestinal antioxidant enzyme activity and MDA content were detected by commercial kits.
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| Number | Date | Country | Kind |
|---|---|---|---|
| 202210132097.6 | Feb 2022 | CN | national |
