Medium-chain fatty acid composition for improving immunity of calf and preparation method thereof

Abstract

The application belongs to the technical field of biological medicine, and particularly relates to a medium-chain fatty acid composition for improving immunity of calves and a preparation method thereof. The medium-chain fatty acid composition for improving immunity of calves according to the application comprises, in terms of weight fractions, 20-30 parts of lactose, 5-10 parts of medium-chain fatty acid, 1-3 parts of mangiferin derivative, 0.5-2 parts of wedelolactone and 0.2-1 part of vitamin C. The mangiferin derivative according to the application can relieve local inflammatory response of the intestinal tract, repair the intestinal mucosal barrier damaged by stress, and enhance the non-specific immune capacity of the body. The wedelolactone according to the application forms a double synergy with the lactose and the medium-chain fatty acid, greatly improves the utilization efficiency of energy and nutrients, and thus promotes the growth and development of the calf. In addition, the wedelolactone can also synergize with the mangiferin derivative, maintains the intestinal health of the calf in the early weaning period, and significantly weakens the weaning stress impact.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, and in particular relates to a medium-chain fatty acid composition for improving the immunity of calves and its preparation method. Background Technology

[0002] In modern beef and dairy cattle farming, calf weaning is a crucial stage. Early weaning not only effectively reduces calf rearing costs but also promotes the early development and maturation of their digestive system (especially the rumen), laying the foundation for the growth and development of replacement dairy cows and the full realization of the productive performance of adult cows. However, the intense stress response accompanying the weaning process can have multiple adverse effects on the calf's physiological functions and behavior, becoming a core pain point restricting farming efficiency.

[0003] At the physiological level, weaning stress triggers a massive release of stress hormones such as cortisol in calves. High levels of cortisol suppress the immune system, leading to a decrease in serum immunoglobulin levels and an increase in inflammatory markers in the liver and gastrointestinal tract after weaning, significantly weakening the body's ability to fight infection. More critically, early weaning damages the mechanical barrier structure of intestinal epithelial cells, abnormally increasing intestinal permeability. This synergistic effect of immunosuppression and barrier damage creates favorable conditions for the translocation and colonization of pathogenic microorganisms, ultimately resulting in a high incidence of intestinal diseases such as diarrhea in post-weaning calves, and in severe cases, even death, causing direct economic losses. Therefore, providing a composition to enhance calf immunity to alleviate weaning stress, improve immunity, and consolidate intestinal health is of urgent practical significance for overcoming current bottlenecks in healthy calf farming and ensuring farming efficiency. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, one objective of this invention is to provide a medium-chain fatty acid composition that enhances calf immunity. The mangiferin derivative of this invention can reduce the secretion of pro-inflammatory factors while upregulating the expression of anti-inflammatory factors, alleviating local intestinal inflammation, and repairing the stress-damaged intestinal mucosal barrier; it also enhances the body's non-specific immunity, compensating for the decline in immune function caused by stress in weaning calves. The wedelia lactone of this invention forms a dual synergistic effect with lactose and medium-chain fatty acids, significantly improving the efficiency of energy and nutrient utilization, thereby promoting calf growth and development. Furthermore, the wedelia lactone and mangiferin derivative of this invention can work synergistically to precisely protect the intestinal health of calves in the pre-weaning period and significantly reduce the impact of weaning stress.

[0005] The second objective of this invention is to provide a method for preparing a medium-chain fatty acid composition that enhances the immunity of calves.

[0006] One of the objectives of this invention is achieved through the following technical solution: A medium-chain fatty acid composition for enhancing calf immunity, comprising, by weight: 20-30 parts lactose, 5-10 parts medium-chain fatty acids, 1-3 parts mangiferin derivative, 0.5-2 parts wedelia lactone, and 0.2-1 parts vitamin C; The chemical structural formula of the mangiferin derivative is as follows: .

[0007] Furthermore, the preparation method of the mangiferin derivative is as follows: (1) Succinic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were dissolved in N,N-dimethylformamide, 4-dimethylaminopyridine was added and stirred to activate the mixture, and then artemisininol was added. The mixture was reacted at room temperature to obtain intermediate 1. (2) Dissolve azide-modified mangiferin and intermediate 1 in a tetrahydrofuran / water / tert-butanol solution, add copper sulfate and sodium ascorbate, and react at room temperature to obtain mangiferin derivative.

[0008] Further, in step (1), the ratio of succinic acid, artemisininol, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 4-dimethylaminopyridine and N,N-dimethylformamide is 5 mmol: 10-12 mmol: 12-15 mmol: 12-15 mmol: 20-50 mL.

[0009] Further, in step (2), the ratio of intermediate 1, azide mangiferin, copper sulfate, sodium ascorbate and tetrahydrofuran / water / tert-butanol solution is 1 mmol: 2-3 mmol: 0.4-0.5 mmol: 0.8-0.9 mmol: 25-50 mL; the tetrahydrofuran / water / tert-butanol solution is prepared by tetrahydrofuran, water and tert-butanol in a volume ratio of 3:1:1.

[0010] Further, the stirring activation time in step (1) is 30-45 min, and the room temperature reaction time is 12-24 h; the room temperature reaction time in step (2) is 24-36 h.

[0011] Further, the preparation method of the azidated mangiferin is as follows: mangiferin is added to anhydrous pyridine, and methanesulfonyl chloride is added dropwise. After stirring overnight at room temperature, the mixture is concentrated under vacuum to obtain a crude product. Then, the crude product is redissolved in dimethylformamide, NaN3 is added, and the mixture is reacted at 60-65℃ for 3-8 hours to obtain azidated mangiferin.

[0012] Furthermore, the ratio of mangiferin, methanesulfonyl chloride, NaN3, anhydrous pyridine, and dimethylformamide is 205 mg: 35-40 μL: 62-65 mg: 5-8 mL: 10-15 mL.

[0013] Furthermore, the medium-chain fatty acid is prepared by mixing decanoic acid and lauric acid in a mass ratio of 1:(2-4).

[0014] The second objective of this invention is achieved by the following technical solution: A method for preparing a medium-chain fatty acid composition to enhance calf immunity includes the following steps: mixing lactose, medium-chain fatty acids, mangiferin derivative, wedelia lactone and vitamin C in the prescribed amounts until homogeneous, thereby obtaining the composition.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention first synthesizes intermediate 1 using succinic acid and artemisinin as raw materials, and further obtains mangiferin derivatives by click reaction of intermediate 1 with azidomangiferin. This derivative can alleviate weaning stress in calves, enhance immunity, and improve intestinal health. The specific mechanism of action is as follows: ① The ester bonds in the mangiferin derivative can be hydrolyzed and broken under the specific catalysis of esterases in the calf's intestine, releasing succinic acid (succinic acid). Succinic acid plays a dual role: Firstly, by inhibiting the activation of the NF-κB inflammatory signaling pathway, it reduces the secretion of pro-inflammatory factors (TNF-α, IL-6) while upregulating the expression of anti-inflammatory factors (IL-10), alleviating local intestinal inflammation and repairing the stress-damaged intestinal mucosal barrier; it also enhances the body's non-specific immunity, compensating for the decline in immune function caused by stress in weaning calves. Furthermore, succinic acid can also serve as an auxiliary energy substrate for intestinal epithelial cells, synergistically providing energy for mucosal cell repair and reducing inflammatory responses in conjunction with lactose breakdown products (glucose, galactose). ② The triazole group generated by the click reaction in mangiferin derivatives has a specific spatial structure and electronic effect, which can inhibit the production of harmful metabolites such as biogenic amines. This not only reduces intestinal mucosal irritation but also indirectly inhibits the metabolic activity of harmful bacteria. It works synergistically with the antibacterial effect of mangiferin derivatives to maintain intestinal environmental stability, creating favorable conditions for the proliferation of beneficial bacteria and the production of short-chain fatty acids, thus maintaining intestinal health. Furthermore, the combined action of the mangiferin core and the triazole group can disrupt the cell membrane integrity of pathogenic bacteria, achieving selective antibacterial activity.

[0016] 2. This invention also incorporates wedelia lactone for synergistic enhancement: ① Wedelia lactone forms a dual synergistic effect with lactose and medium-chain fatty acids, significantly improving energy and nutrient utilization efficiency, thereby promoting the growth and development of calves. On the one hand, wedelia lactone can improve local intestinal circulation, accelerate the transport and delivery of glucose, galactose, and other nutrients to damaged mucosal sites, providing sufficient nutrition for beneficial bacteria colonization while also strengthening the basic role of lactose in promoting beneficial bacteria proliferation; on the other hand, wedelia lactone can also promote the transport and distribution of absorbed medium-chain fatty acids in the body, enabling them to reach energy-demanding sites such as muscles and immune organs more quickly, further enhancing the rapid energy supply and stress relief effects of medium-chain fatty acids, and comprehensively improving energy utilization efficiency. ② Wedelia lactone and mangiferin derivatives work synergistically to precisely protect the intestinal health of calves before weaning and significantly reduce the impact of weaning stress: Wedelia lactone can strengthen the tightness of the connection between intestinal epithelial cells and consolidate the intestinal mechanical barrier defense capability; mangiferin derivatives can inhibit harmful bacteria and reduce the inducing factors of mucosal inflammation, and the released succinic acid can relieve local intestinal inflammation and assist in mucosal repair. The combined effect of the two not only reduces the damage of inflammation to the intestinal barrier, but also improves the intestinal barrier's anti-stress capability from the root, effectively resisting the intestinal barrier damage caused by weaning stress and reducing the risk of systemic inflammation and diarrhea. Detailed Implementation

[0017] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0018] Example 1 A medium-chain fatty acid composition for enhancing calf immunity comprises, by weight: 25 parts lactose, 8 parts medium-chain fatty acids, 2 parts mangiferin derivative, 1 part wedelia lactone, and 0.8 parts vitamin C; The medium-chain fatty acid is prepared by mixing decanoic acid and lauric acid in a mass ratio of 1:3.

[0019] The preparation method of the mangiferin derivative is as follows: (1) Succinic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were dissolved in N,N-dimethylformamide, and 4-dimethylaminopyridine was added and stirred for 40 min to activate the mixture. Then, artemisininol was added, wherein the ratio of succinic acid, artemisininol, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 4-dimethylaminopyridine and N,N-dimethylformamide was 5 mmol: 11 mmol: 13 mmol: 13 mmol: 40 mL. The reaction was then carried out at room temperature for 20 h. The reaction was terminated by adding deionized water, extracted with dichloromethane, washed with saturated brine, dried over anhydrous MgSO4, filtered, evaporated under reduced pressure, and purified by column chromatography to obtain intermediate 1. 1 HNMR: (C 28 H 30 O4, 400MHz, DMSO- d6 ) δ: 1.33-1.37 (d, 6H), 2.06-2.10 (m, 2H), 2.31-2.35 (m, 2H), 2.64 (s, 4H), 3 .22-3.26 (m, 4H), 4.78-4.82 (m, 2H), 7.14-7.18 (m, 4H), 7.20-7.27 (m, 6H). MS (ESI) m / z=430.21 [M].

[0020] (2) Mangiferin was added to anhydrous pyridine at a ratio of 205 mg to 7 mL. Methylsulfonyl chloride was added dropwise, and the mixture was stirred overnight at room temperature. The mixture was then concentrated under vacuum to obtain a crude product. The crude product was then redissolved in dimethylformamide, and NaN3 was added. The ratio of mangiferin, methylsulfonyl chloride, NaN3, and dimethylformamide was 205 mg: 40 μL: 64 mg: 13 mL. After reacting at 65 °C for 5 h, the mixture was purified by column chromatography to obtain azidomangiferin. The azidomangiferin... 1 HNMR: (C 19 H 17 O 10 N3, 400MHz, DMSO- d6 ) δ: 1.28-1.32 (m, H), 1.58-1.62 (m, H), 3.58-3.62 (m, 2H), 3.68-3.72 (m, H), 4.06-4.10 (m, H), 4.37 (s, H) , 4.51 (s, 2H), 4.86-4.90 (d, H), 6.15 (s, H), 6.39 (s, H), 6.88 (s, H), 9.48 (s, 2H), 9.68 (s, H), 12.04 (s, H). MS (ESI) m / z=447.09 [M].

[0021] (3) Azide-modified mangiferin and intermediate 1 were dissolved in a tetrahydrofuran / water / tert-butanol solution (v / v / v, 3:1:1), and copper sulfate and sodium ascorbate were added. The ratio of intermediate 1, azide-modified mangiferin, copper sulfate, sodium ascorbate, and tetrahydrofuran / water / tert-butanol solution was 1 mmol: 2.5 mmol: 0.45 mmol: 0.85 mmol: 40 mL. After reacting at room temperature for 30 h, the reaction was quenched with water, extracted with ethyl acetate, and the organic phase was concentrated and purified by column chromatography to obtain the mangiferin derivative. The mangiferin derivative... 1 HNMR: (C 66 H 64 O 24 N6, 400MHz, DMSO- d6 ) δ: 1.33-1.37 (d, 6H), 2.62-2.67 (m, 6H), 2.88-2.92 (m, 2H), 3.58-3.62 (m, 4H) , 3.68-3.73 (m, 4H), 3.81 (s, 4H), 3.94-3.98 (m, 2H), 4.06-4.10 (m, 2H), 4.37 (s , 2H), 4.51 (s, 4H), 4.86-4.90 (d, 2H), 5.13-5.17 (m, 2H), 6.15 (s, 2H), 6.39 (s, 2H), 6.88 (s, 2H), 7.18-7.30 (m, 10H), 9.48 (s, 4H), 9.68 (s, 2H), 12.04 (s, 2H). MS (ESI) m / z=1324.40 [M].

[0022] A method for preparing a medium-chain fatty acid composition to enhance calf immunity includes the following steps: mixing lactose, medium-chain fatty acids, mangiferin derivative, wedelia lactone and vitamin C in the prescribed amounts until homogeneous, thereby obtaining the composition.

[0023] Example 2 A medium-chain fatty acid composition for enhancing calf immunity comprises, by weight: 20 parts lactose, 5 parts medium-chain fatty acids, 1 part mangiferin derivative, 0.5 parts wedelia lactone, and 0.2 parts vitamin C; The medium-chain fatty acid is prepared by mixing decanoic acid and lauric acid in a mass ratio of 1:2.

[0024] The preparation method of the mangiferin derivative is as follows: (1) Succinic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were dissolved in N,N-dimethylformamide, and 4-dimethylaminopyridine was added and stirred for 30 min to activate the mixture. Then, artemisininol was added, wherein the ratio of succinic acid, artemisininol, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 4-dimethylaminopyridine and N,N-dimethylformamide was 5 mmol: 10 mmol: 12 mmol: 12 mmol: 20 mL. The reaction was then carried out at room temperature for 12 h. The reaction was terminated by adding deionized water, extracted with dichloromethane, washed with saturated brine, dried over anhydrous MgSO4, filtered, evaporated under reduced pressure, and purified by column chromatography to obtain intermediate 1. 1 The HNMR and MS (ESI) characterization results are the same as in Example 1.

[0025] (2) Mangiferin was added to anhydrous pyridine in a ratio of 205 mg to 5 mL. Methylsulfonyl chloride was added dropwise and stirred overnight at room temperature. The crude product was then concentrated under vacuum. The crude product was then redissolved in dimethylformamide and NaN3 was added. The ratio of mangiferin, methylsulfonyl chloride, NaN3 and dimethylformamide was 205 mg to 35 μL to 62 mg to 10 mL. After reacting at 60 °C for 8 h, the product was purified by column chromatography to obtain azide-modified mangiferin. (3) Azide-modified mangiferin and intermediate 1 were dissolved in a tetrahydrofuran / water / tert-butanol solution (v / v / v, 3:1:1), and copper sulfate and sodium ascorbate were added. The ratio of intermediate 1, azide-modified mangiferin, copper sulfate, sodium ascorbate, and tetrahydrofuran / water / tert-butanol solution was 1 mmol: 2 mmol: 0.4 mmol: 0.8 mmol: 25 mL. After reacting at room temperature for 24 h, the reaction was quenched with water, extracted with ethyl acetate, and the organic phase was concentrated and purified by column chromatography to obtain the mangiferin derivative. 1 The HNMR and MS (ESI) characterization results are the same as in Example 1.

[0026] A method for preparing a medium-chain fatty acid composition to enhance calf immunity includes the following steps: mixing lactose, medium-chain fatty acids, mangiferin derivative, wedelia lactone and vitamin C in the prescribed amounts until homogeneous, thereby obtaining the composition.

[0027] Example 3 A medium-chain fatty acid composition for enhancing calf immunity comprises, by weight: 30 parts lactose, 10 parts medium-chain fatty acids, 3 parts mangiferin derivative, 2 parts wedelia lactone, and 1 part vitamin C; The medium-chain fatty acid is prepared by mixing decanoic acid and lauric acid in a mass ratio of 1:4.

[0028] The preparation method of the mangiferin derivative is as follows: (1) Succinic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were dissolved in N,N-dimethylformamide, and 4-dimethylaminopyridine was added and stirred for 45 min to activate the mixture. Then, artemisininol was added, wherein the ratio of succinic acid, artemisininol, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 4-dimethylaminopyridine and N,N-dimethylformamide was 5 mmol: 12 mmol: 15 mmol: 15 mmol: 50 mL. The reaction was then carried out at room temperature for 24 h. The reaction was terminated by adding deionized water, extracted with dichloromethane, washed with saturated brine, dried over anhydrous MgSO4, filtered, evaporated under reduced pressure, and purified by column chromatography to obtain intermediate 1. 1 The HNMR and MS (ESI) characterization results are the same as in Example 1.

[0029] (2) Mangiferin was added to anhydrous pyridine in a ratio of 205 mg to 8 mL. Methylsulfonyl chloride was added dropwise and stirred overnight at room temperature. The crude product was then concentrated under vacuum. The crude product was then redissolved in dimethylformamide and NaN3 was added. The ratio of mangiferin, methylsulfonyl chloride, NaN3 and dimethylformamide was 205 mg to 40 μL to 65 mg to 15 mL. After reacting at 65 °C for 3 h, the product was purified by column chromatography to obtain azide-modified mangiferin. (3) Azide-modified mangiferin and intermediate 1 were dissolved in a tetrahydrofuran / water / tert-butanol solution (v / v / v, 3:1:1), and copper sulfate and sodium ascorbate were added. The ratio of intermediate 1, azide-modified mangiferin, copper sulfate, sodium ascorbate, and tetrahydrofuran / water / tert-butanol solution was 1 mmol:3 mmol:0.5 mmol:0.9 mmol:50 mL. After reacting at room temperature for 36 h, the reaction was quenched with water, extracted with ethyl acetate, and the organic phase was concentrated and purified by column chromatography to obtain the mangiferin derivative. 1 The HNMR and MS (ESI) characterization results are the same as in Example 1.

[0030] A method for preparing a medium-chain fatty acid composition to enhance calf immunity includes the following steps: mixing lactose, medium-chain fatty acids, mangiferin derivative, wedelia lactone and vitamin C in the prescribed amounts until homogeneous, thereby obtaining the composition.

[0031] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that mangiferin is used instead of mangiferin derivative; otherwise, they are the same as in Example 1.

[0032] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that wedelia lactone is omitted; otherwise, they are the same as in Example 1.

[0033] Experimental Example 1 1. Holstein calves, weighing 60-70 kg, were selected as experimental animals and randomly divided into 6 groups: Examples 1-3, Comparative Examples 1-2, and a control group, with 10 calves in each group. Examples 1-3 and Comparative Examples 1-2 were fed starter feed plus 0.5% of the medium-chain fatty acid composition obtained from Examples 1-3 and Comparative Examples 1-2 by weight of the starter feed. All calves had free access to water. The control group was fed starter feed and had free access to water. The experiment lasted 28 days. The starter feed composition for calves was as follows: corn 36.72%; soybean meal 24.5%; cottonseed meal 5.08%; soybean hulls 9.13%; wheat bran 5.06%; dried distillers' grains and their solubles 5%; corn germ meal 9.03%; limestone 2.25%; calcium dihydrogen phosphate 1.23%; and premix 2.0%. Each kilogram of premix contains: calcium 1.24g, iron 9.15mg, manganese 15.82mg, copper 8.60mg, zinc 28.98mg, selenium 0.80mg, iodine 0.80mg, cobalt 1.10mg, vitamin A 695IU and vitamin E 260IU, vitamin D 75.86IU.

[0034] 2. Sample index determination (1) Average daily weight gain On day 28 of the experiment, the weight of the calves before morning feeding was measured, and the average daily weight gain of the calves was calculated.

[0035] (2) The effect of feed on calf diarrhea Calf feces were observed during morning feeding each day. Diarrhea was defined as a score ≥3 according to the scoring criteria (see Table 1). The number of calf diarrhea episodes during the experiment was recorded. The results are shown in Table 2.

[0036] (3) Intestinal microbiome detection Before morning feeding on day 28 of the experiment, fecal samples were collected from five healthy calves randomly selected from each group. Approximately 5g of fecal matter from the distal rectum of each calf was collected using a sterile fecal sampler. Genomic DNA was extracted using the cetyltrimethylammonium bromide (CTAB) method. The extracted DNA was amplified by PCR, and the amplified products were then mixed, cultured, and purified. Subsequently, end-repair, A-tailing, sequencing adapter addition, and purification steps were performed to construct the library. Finally, the prepared library was subjected to high-throughput sequencing to analyze and compare the differences in gut microbiota among the calves in each group. The results are detailed in Tables 3-4.

[0037] (4) Measurement of immune proteins and inflammatory factors On day 28, before morning feeding, fasting blood samples were collected from calves to detect the levels of immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) in their serum. The results are shown in Table 5. The levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) in calf serum were also detected. The results are shown in Table 6.

[0038] Table 1 Table 2 As shown in Table 2, the number of diarrheal episodes in Examples 1-3 of the present invention was lower than that in Comparative Examples 1-2, indicating that the medium-chain fatty acid composition of the present invention can effectively prevent diarrhea in calves during weaning. The number of diarrheal episodes in Comparative Examples 1 and 2 was significantly higher than that in Example 1, indicating that the lack of mangiferin derivatives or wedelia lactone significantly reduced the antidiarrheal effect.

[0039] The average daily weight gain of Examples 1-3 was better than that of Comparative Examples 1-2, with Example 1 being the best. The average daily weight gain of Comparative Examples 1 and 2 was lower than that of Example 1, indicating that mangiferin derivatives or wedelia lactones play a key and irreplaceable role in consolidating the intestinal physical barrier and improving nutrient transport efficiency, which will affect the growth and development of calves.

[0040] Table 3 Table 4 As shown in Tables 3 and 4, after treatment with the medium-chain fatty acid compositions obtained in Examples 1-3 of this invention, the levels of Firmicutes, Faecalibacterium, Prevotella, and other bacteria in the calf intestines decreased. Clostridia_UCG-014 The relative abundance of [unspecified organisms] increased, while the relative abundance of Bacteroidetes, Proteobacteria, Fusobacteria, and Bacteroidetes decreased. The effects of Comparative Examples 1 and 2 were not as good as those of Example 1. These results indicate that the medium-chain fatty acid composition of the present invention can reduce weaning stress in calves, promote the colonization of beneficial bacteria, optimize the intestinal flora structure, and stabilize the intestinal barrier.

[0041] Table 5 As shown in Table 5, the levels of the three immunoglobulins (IgA, IgM, and IgG) in Examples 1-3 of this invention were significantly higher than those in Comparative Examples 1-3. The levels of immunoglobulins in Comparative Examples 1 and 2 were significantly lower than those in Example 1. This indicates that the mangiferin derivative in the chain fatty acid composition of this invention can enhance the body's non-specific immunity and compensate for the decline in immune function caused by stress in weaned calves. Furthermore, the mangiferin derivative and wedelia lactone exhibit deep synergy, contributing to the improvement of calf immunity.

[0042] Table 6 As shown in Table 6, the levels of inflammatory factors (IL-6 and TNF-α) in Examples 1-3 of this invention were lower than those in Comparative Examples 1-2, while the level of IL-10 was significantly increased. This is because the mangiferin derivative in this invention can directionally release succinic acid, which reduces the secretion of pro-inflammatory factors (TNF-α, IL-6) by inhibiting the activation of the NF-κB inflammatory signaling pathway, while upregulating the expression of anti-inflammatory factor (IL-10), thereby alleviating the local inflammatory response in the intestine.

[0043] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A medium-chain fatty acid composition for enhancing calf immunity, characterized in that, The medium-chain fatty acid composition for enhancing calf immunity comprises, by weight: 20-30 parts lactose, 5-10 parts medium-chain fatty acids, 1-3 parts mangiferin derivative, 0.5-2 parts wedelia lactone, and 0.2-1 parts vitamin C; The chemical structural formula of the mangiferin derivative is as follows: 。 2. The medium-chain fatty acid composition for enhancing calf immunity according to claim 1, characterized in that, The preparation method of the mangiferin derivative is as follows: (1) Succinic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide were dissolved in N,N-dimethylformamide, 4-dimethylaminopyridine was added and stirred to activate the mixture, and then artemisininol was added. The mixture was reacted at room temperature to obtain intermediate 1. (2) Dissolve azide mangiferin and intermediate 1 in tetrahydrofuran / water / tert-butanol solution, add copper sulfate and sodium ascorbate, and react at room temperature to obtain mangiferin derivative; The chemical structural formula of intermediate 1 is as follows: ； The chemical structural formula of the azido-mangiferin is: 。 3. The medium-chain fatty acid composition for enhancing calf immunity according to claim 2, characterized in that, In step (1), the ratio of succinic acid, artemisininol, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 4-dimethylaminopyridine and N,N-dimethylformamide is 5 mmol: 10-12 mmol: 12-15 mmol: 12-15 mmol: 20-50 mL.

4. The medium-chain fatty acid composition for enhancing calf immunity according to claim 2, characterized in that, In step (2), the ratio of intermediate 1, azide mangiferin, copper sulfate, sodium ascorbate and tetrahydrofuran / water / tert-butanol solution is 1 mmol: 2-3 mmol: 0.4-0.5 mmol: 0.8-0.9 mmol: 25-50 mL; the tetrahydrofuran / water / tert-butanol solution is prepared by tetrahydrofuran, water and tert-butanol in a volume ratio of 3:1:

1.

5. The medium-chain fatty acid composition for enhancing calf immunity according to claim 2, characterized in that, The stirring activation time in step (1) is 30-45 min, and the room temperature reaction time is 12-24 h; the room temperature reaction time in step (2) is 24-36 h.

6. The medium-chain fatty acid composition for enhancing calf immunity according to claim 2, characterized in that, The preparation method of the azidated mangiferin is as follows: mangiferin is added to anhydrous pyridine, and methanesulfonyl chloride is added dropwise. After stirring overnight at room temperature, the crude product is concentrated under vacuum to obtain crude product. Then, the crude product is redissolved in dimethylformamide, NaN3 is added, and the reaction is carried out at 60-65℃ for 3-8 hours to obtain azidated mangiferin.

7. The medium-chain fatty acid composition for enhancing calf immunity according to claim 6, characterized in that, The ratio of mangiferin, methanesulfonyl chloride, NaN3, anhydrous pyridine, and dimethylformamide is 205 mg: 35-40 μL: 62-65 mg: 5-8 mL: 10-15 mL.

8. The medium-chain fatty acid composition for enhancing calf immunity according to claim 1, characterized in that, The medium-chain fatty acid is prepared by mixing decanoic acid and lauric acid in a mass ratio of 1:(2-4).

9. The method for preparing the medium-chain fatty acid composition for enhancing calf immunity according to any one of claims 1-8, characterized in that, The process includes the following steps: mixing the prescribed amounts of lactose, medium-chain fatty acids, mangiferin derivatives, wedelia lactone, and vitamin C evenly to obtain the final product.

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