FEED ADDITIVE FOR IMPROVING INTESTINAL STRUCTURE OF LARIMICHTHYS CROCEA, FEED, AND USE

Abstract

The present disclosure relates to a feed additive for improving intestinal structure of Larimichthys crocea, a feed and use, and belongs to the field of aquatic animal nutritional feeds. 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 additive in improving the intestinal structure of the L. crocea, and the use lasts for at least 70 days. The feed provided by the present disclosure can effectively improve intestinal morphological change, reduced intestinal villi, reduced intestinal perimeter ratio, and intestinal barrier damage caused by replacement of fish oil with soybean oil; and damage of intestinal antioxidant activity caused by replacement of fish oil with soybean oil is relieved.

Claims

1. A feed additive for improving intestinal structure of Larimichthys crocea, wherein the feed additive comprises glyceryl monolaurate.

2. A feed comprising the feed additive according to claim 1, wherein a mass percentage of the glyceryl monolaurate in the feed is 0.04%.

3. A treatment method for improving intestinal structure of Larimichthys crocea by using the feed according to claim 2, wherein the treatment lasts for at least 70 days.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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.

[0016] FIG. 1A-E illustrate hematoxylin-eosin (H&E) staining results of intestinal morphology of L. crocea across groups in Example 1 of the present disclosure; FIG. 1A represents the fish oil group, FIG. 1B represents the soybean oil group, FIG. 1C represents the soybean oil group added with 0.02% (w/w) glycerol monolaurate, FIG. 1D represents the soybean oil group added with 0.04% (w/w) glyceryl monolaurate, and FIG. 1E represents the soybean oil groups added with 0.08% (w/w) glyceryl monolaurate;

[0017] FIG. 2 illustrates intestinal villus height, muscle layer thickness and perimeter ratio of L. crocea across groups in Example 1 of the present disclosure;

[0018] FIG. 3 illustrates the expression of genes related to the intestinal physical barrier of L. crocea across groups in Example 1 of the present disclosure; and

[0019] FIG. 4 illustrates the intestinal antioxidant enzyme activity and MDA content of L. crocea across groups in Example 1 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] 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.

Example 1. Feed Manufacturing and Aquaculture Management Using this Method

[0021] 1. Experimental Design and Experimental Feed Formula

[0022] 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.

TABLE-US-00001 TABLE 1 Formula and crude composition of experimental feed (% dry composition) Fish Soybean oil oil Addition Addition Addition group group group group group Feed composition (FO) (SO) (G0.02) (G0.04) (G0.08) White fish meal.sup.1 32 32 32 32 32 Premium krill 1 1 1 1 1 meal.sup.1 Dehulled soybean 25 25 25 25 25 meal.sup.1 Bread flour.sup.1 28.79 28.79 28.79 28.79 28.79 Fish oil 7 0 0 0 0 Soybean oil 0 7 7 7 7 Soyabean lecithin 2 2 2 2 2 Compound 0.2 0.2 0.2 0.2 0.2 vitamin premix.sup.2 Compound 1 1 1 1 1 mineral premix.sup.2 Monocalcium 2 2 2 2 2 phosphate Ascorbyl 0.05 0.05 0.05 0.05 0.05 phosphate Mould inhibitor 0.05 0.05 0.05 0.05 0.05 Choline chloride 0.2 0.2 0.2 0.2 0.2 Ethoxyquin 0.05 0.05 0.05 0.05 0.05 Feed attractant.sup.4 0.5 0.5 0.5 0.5 0.5 Glyceryl 0 0 0.02 0.04 0.08 monolaurate.sup.5 Microcrystalline 0.16 0.16 0.14 0.12 0.08 cellulose (MCC) Nutrient % Crude protein 42.16 42.96 42.53 42.98 42.17 (CP) Ether extract 12.59 12.52 12.30 12.64 12.60 (EE) .sup.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). .sup.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) .sup.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;) .sup.4Glycine and betaine. .sup.5Glycerol monolaurate: 92% pure.

[0023] 2. Experimental Fish and Aquaculture Management

[0024] 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.

[0025] 3. Collection and Analysis of Experimental Samples

[0026] 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.

[0027] As shown in FIG. 1A-E, compared with the fish oil group, the soybean oil group showed obvious damage to the intestinal structure, while the damage to the intestinal structure was alleviated and the number of intestinal villi increased in the addition group that used this method.

[0028] As shown in FIG. 2, the intestinal villus height and the intestinal perimeter ratio were significantly reduced in the soybean oil group, while the intestinal villus height was relatively improved in the addition group that used this method; the intestinal perimeter ratio in the 0.04% addition group was significantly higher than that in the soybean oil group.

[0029] As shown in FIG. 3, the expression of intestinal barrier-related genes was significantly downregulated in the soybean oil group, while the expression of intestinal barrier-related genes was relatively unregulated in the addition group that used this method; the expression of intestinal barrier-related genes in the 0.04% addition group was significantly higher than that of the soybean oil group.

[0030] As shown in FIG. 4, the intestinal antioxidant enzyme activity decreased significantly and the MDA content decreased in the soybean oil group, while the antioxidant activity was significantly improved in the addition group that used this method. Herein, the antioxidant activity of the 0.04% addition group was significantly higher than that of the soybean oil group.