Feed additive, pig feed and application thereof

Abstract

The invention belongs to the technical field of animal husbandry breeding, and particularly relates to a feed additive, a pig feed and application thereof. The feed additive comprises hydroxytyrosol and theaflavin in a mass ratio of (0.5-2): 1. According to the present invention, the hydroxytyrosol and the theaflavin are adopted as the active components, and the hydroxytyrosol and the theaflavin are added into the feed to feed the pigs at different growth stages, such that the growth requirements of the pigs at the whole stage can be met, the frequent adjustment of the feed composition is not required, the breeding continuity and the adaptability of the pigs to the feed are easily achieved, and the significant economic benefits are provided.

Description

Technical Field

[0001] The invention relates to the technical field of animal husbandry, and in particular to a feed additive and pig feed and applications thereof. Background Art

[0002] At present, the breeding industry is developing rapidly in the direction of scale and standardization. How to improve the production efficiency of pigs is an important goal of the current pig farming industry. The key to restricting the production efficiency of pigs lies in the production and reproduction performance of sows and the growth performance of weaned piglets. Usually, the nutritional components of ordinary pig feed are not enough to ensure the physical health of sows and the normal development of piglets in the body, resulting in low production and reproduction capacity of sows, low lactation capacity, small number of live piglets and low birth weight of piglets. At the same time, after weaning, the nutrients for growth and development of suckling pigs change, causing great changes in physiology, reduced resistance and immunity, and easily leading to diarrhea, slow growth and other problems in piglets. It is necessary to configure nutritionally reasonable feed for feeding. The application of feed additives is an effective way to alleviate these adverse effects. Feed additives refer to a raw material or a mixture of several raw materials added to the basic feed mixture or part of the feed for some special needs.

[0003] At present, pig feed additives are mainly added with trace minerals, vitamins and hormones, and there are still some shortcomings. Different feed additives are often needed at different stages of pig growth, but too frequent changes in feed formulas lead to sudden changes in taste, which is not conducive to the sustainability of breeding. Therefore, developing a feed additive that can meet the growth and production needs of pigs at different physiological stages to adapt to the nutritional needs of sows and piglets is of great significance for the healthy and sustainable development of the pig farming industry. Summary of the invention

[0004] In view of the above technical problems in the prior art, the present invention provides a feed additive and a pig feed containing the feed additive. The present invention uses hydroxytyrosol and theaflavins as active ingredients of the feed additive, and adds them to feed to feed pigs at different growth stages, which can meet the growth needs of pigs at all stages, without the need to frequently adjust the feed composition, which is beneficial to the sustainability of breeding and the adaptability of pigs to feed, and has significant economic benefits. Therefore, the present invention further provides the use of the feed additive and the pig feed in pig breeding.

[0005] To achieve the above object, the present invention is specifically implemented through the following technical solutions:

[0006] The first aspect of the present invention provides a feed additive, comprising hydroxytyrosol and theaflavin in a mass ratio of 0.5-2:1.

[0007] Furthermore, the feed additive comprises hydroxytyrosol and theaflavin in a mass ratio of 1:1.

[0008] A second aspect of the present invention provides a pig feed, comprising the feed additive and basic feed as described above.

[0009] Furthermore, the feed additive accounts for 0.005%-0.04% (wt) of the total mass of the basic feed. Still further, the feed additive accounts for 0.02% (wt) of the total mass of the basic feed.

[0010] The third aspect of the present invention provides the use of the feed additive or pig feed as described above in improving the production performance of sows.

[0011] Further, improving the production performance of sows includes at least one of the following (1)-(2):

[0012] (1) Increase the weight of lactating piglets;

[0013] (2) Increasing the content of milk protein, milk fat, lactose and immunoglobulin in sow colostrum, wherein the immunoglobulin includes one or more of IgG, IgA and IgM.

[0014] A fourth aspect of the present invention provides use of the feed additive or pig feed as described above in improving the growth performance of weaned piglets.

[0015] Further, improving the growth performance of weaned piglets includes at least one of the following (1)-(5):

[0016] (1) Increase the feed intake of weaned piglets;

[0017] (2) Improve the daily weight gain of weaned piglets;

[0018] (3) Reduce the feed-to-weight ratio of weaned piglets;

[0019] (4) Reduce the diarrhea rate and diarrhea index of weaned piglets;

[0020] (5) Improve the intestinal flora of weaned piglets, including increasing the number of Lactobacillus, Bifidobacterium and Bacillus and reducing the number of Escherichia coli.

[0021] The fifth aspect of the present invention provides the use of the feed additive or pig feed as described above in improving the antibody level of piglets after immunization with a vaccine.

[0022] Furthermore, improving the antibody level of piglets after immunization includes at least one of the following (1)-(2):

[0023] (1) Increase serum antibody levels after vaccination with inactivated circovirus type 2 vaccine;

[0024] (2) Improve the antibody positivity rate after vaccination with inactivated circovirus type 2 vaccine.

[0025] The advantages and positive effects of the present invention are:

[0026] The present invention uses hydroxytyrosol and theaflavins as active ingredients, adds them to feed to feed pigs at different growth stages, can meet the growth needs of pigs at all stages, does not need to frequently adjust the feed composition, is conducive to the sustainability of breeding and the adaptability of pigs to feed, and has significant economic benefits. When used for sow breeding during pregnancy, it can improve the production and reproduction performance of sows, improve the nutritional components and immunoglobulin content of lactating sows, is conducive to sows providing enough nutritional energy to suckling pigs and improving the immunity and anti-infection ability of suckling pigs, and significantly promotes the growth and development of suckling piglets. When used for weaned piglet breeding, it can greatly alleviate the diarrhea of ​​suckling pigs after weaning, improve intestinal health, increase the food intake of weaned piglets and improve the utilization rate of feed, and significantly enhance the growth and development ability of weaned piglets. In addition, when used for the breeding of lactating piglets and weaned piglets, it can also enhance the immune response of piglets to vaccines, and improve the serum antibody content and positive rate. DETAILED DESCRIPTION

[0027] Based on the information contained in the present invention, it is easy for those skilled in the art to make various changes to the precise description of the present invention without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present invention is not limited to the defined processes, properties or components, because these embodiments and other descriptions are only for the purpose of illustrating specific aspects of the present invention. In fact, various changes that a person skilled in the art or related fields can obviously make to the embodiments of the present invention are covered within the scope of the appended claims.

[0028] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers and other numerical values ​​used in the present invention to express the amount, percentage, etc. should be understood as modified by the word "approximately" in all cases. The term "approximately" has its usual meaning, which is used to indicate that a value includes the inherent variation of the error of the device or method used to determine the value, or contains a value close to the value, such as within 10% of the value (or range of values). Therefore, unless otherwise specified, the numerical parameters listed in the specification and the attached claims are approximate values, which may be changed according to the different ideal properties attempted to be obtained. In addition, it should be noted that the meaning of the terms "including", "comprising", "containing", "having" and the like is non-restrictive, that is, other steps and other ingredients that do not affect the results can be added.

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] An embodiment of the present invention provides a feed additive, comprising hydroxytyrosol and theaflavin in a mass ratio of 0.5-2:1.

[0031] The present invention uses hydroxytyrosol and theaflavins as active ingredients, and adds them to feed to feed pigs at different growth stages. Specifically, adding the feed additive of the present invention to the feed of pregnant sows can improve the production and reproduction performance of sows, increase the content of nutrients (such as milk protein, milk fat, lactose) and immunoglobulins (such as IgG, IgA and IgM) in the lactation of lactating sows, and is conducive to providing sufficient nutritional energy to suckling pigs and improving the immunity and anti-infection ability of suckling pigs, and significantly promotes the growth and development of suckling piglets. Compared with the control group, the weight of the suckling pigs in the group fed with the feed additive of the present invention at weaning can be increased by 12.27%. In addition, the feed additive of the present invention is added to the feed of weaned piglets, the diarrhea situation after weaning of suckling piglets can be greatly alleviated, the reproduction of probiotics such as its intestinal lactobacillus, bifidobacterium and the growth of pathogenic bacteria such as Escherichia coli are promoted, and the intestinal health is improved, and the weaned piglets food intake is increased and the utilization rate of feed is improved, and the feed-to-weight ratio can be as low as 1.59 ± 0.03, which is conducive to accelerating the growth of piglets, and the average daily weight gain of piglets can reach 384.15 ± 8.68 grams, significantly enhancing the growth and development ability of weaned piglets. In addition, the feed additive of the present invention is used for the feeding of suckling piglets and weaned piglets, and the immune response of piglets to vaccines can be enhanced. After inoculation of circovirus type 2 inactivated vaccine, its serum antibody content and positive rate are significantly improved compared with the control group. In a word, the feed additive of the present invention can meet the growth demand of pigs in all stages, and there is no need to frequently adjust the feed composition, which is conducive to the sustainability of breeding and the adaptability of pigs to feed, and has significant economic benefits.

[0032] Preferably, the feed additive comprises hydroxytyrosol and theaflavin in a mass ratio of 1:1.

[0033] More preferably, the feed additive consists of hydroxytyrosol and theaflavins in a mass ratio of 1:1.

[0034] Yet another embodiment of the present invention provides a pig feed, comprising the feed additive and basic feed as described above.

[0035] The advantages of the pig feed over the prior art are the same as the advantages of the feed additive over the prior art as described above, and will not be repeated here.

[0036] Optionally, the feed additive accounts for 0.005%-0.04% (wt) of the total mass of the basic feed. Preferably, the feed additive accounts for 0.02% (wt) of the total mass of the basic feed.

[0037] Another embodiment of the present invention provides the use of the feed additive or pig feed as described above in at least one of the following (a)-(c):

[0038] (a) Improve the production performance of sows;

[0039] (b) Improve the growth performance of weaned piglets;

[0040] (c) Improve the antibody level of piglets after vaccination.

[0041] Optionally, at least one of the following (1)-(2) is used to improve the production performance of sows: (1) increasing the body weight of lactating piglets; (2) increasing the content of milk protein, milk fat, lactose and immunoglobulins in the colostrum of sows, wherein the immunoglobulins include one or more of IgG, IgA and IgM.

[0042] Optionally, at least one of the following (1)-(5) is used to improve the growth performance of weaned piglets: (1) increasing the feed intake of weaned piglets; (2) increasing the daily weight gain of weaned piglets; (3) reducing the feed-to-weight ratio of weaned piglets; (4) reducing the diarrhea rate and diarrhea index of weaned piglets; (5) improving the intestinal flora of weaned piglets, including increasing the number of probiotics and reducing the number of pathogenic bacteria, the probiotics including one or more of lactobacilli, bifidobacteria and bacilli, and the pathogenic bacteria including Escherichia coli.

[0043] Optionally, improving the antibody level of piglets after vaccination includes at least one of the following (1)-(2): (1) improving the serum antibody content after vaccination with inactivated circovirus type 2 vaccine; (2) improving the antibody positivity rate after vaccination with inactivated circovirus type 2 vaccine.

[0044] The present invention is further described below in conjunction with specific examples. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0045] In the following examples, hydroxytyrosol and theaflavins were commercially available, wherein hydroxytyrosol was purchased from Anhui Zhonghong Bioengineering Co., Ltd., with a content of ≥99%, and theaflavins were purchased from Hubei Haijia Biotechnology Co., Ltd., with a CAS number of 4670-05-7 and a content of ≥99%. The remaining reagents were purchased from Sinopharm Reagents unless otherwise specified.

[0046] Example

[0047] 1. Effects of feed additives on sow production performance (gestation + lactation)

[0048] Forty sows of Changda (Landrace (sire) × Large White (mother)) with similar due date and parity were selected and randomly divided into four groups, with two replicates in each group and five pigs in each replicate. The groups were set as control group (fed with basal diet), hydroxytyrosol group (0.02% hydroxytyrosol added to basal diet), theaflavin group (0.02% theaflavin added to basal diet) and compound group (0.01% hydroxytyrosol and 0.01% theaflavin added to basal diet). The basal diets for pregnant sows and lactating sows were provided by Jingzhou Haida Feed Co., Ltd. The names of the basal diets for pregnancy and lactation were 886 and 887, respectively.

[0049] After mating, the sows enter the pre-feeding period, during which additives are fed according to the grouping situation for 7 days; then they enter the formal feeding stage until weaning, which is the test period. During the entire feeding period, pregnant sows have free access to water, and feed is added at 7:00 and 14:00 every day. In the early stage of pregnancy, they are fed 2.4kg / head per day, in the late stage of pregnancy, they are fed 3.5kg / head per day, and in the lactation period, they are fed 6kg / head per day. One week before the sows are due to give birth, the delivery room is thoroughly disinfected and sterilized to ensure that the delivery bed and incubator are clean, and the temperature and humidity are adjusted.

[0050] 1.1. Piglet growth performance index test

[0051] Within 12 hours after the sow farrowed, the weight of the piglets was weighed one by one, and the weight of the weaned piglets was recorded when the piglets were weaned on the 21st day of age. The results are shown in Table 1.

[0052] Table 1 Effects of adding different feed additives to the basic diet on the growth performance of piglets

[0053]

[0054] As can be seen from Table 1, compared with the control group, the addition of the feed additive of the present invention to the diet of sows during pregnancy had no significant effect on the weight of newborn piglets. However, in the group of adding hydroxytyrosol, theaflavin and the complex of the two to the diet of sows during lactation, the weight of piglets increased significantly when weaned, and the weight increased by 8.44%, 9.05% and 12.27% respectively compared with the control group without any feed additives. The weight gain effect of piglets using the feed additive of the two composites was significantly better than that of the two alone.

[0055] 1.2. Determination of related indicators of colostrum in sows after pregnancy

[0056] Determination of colostrum-related indicators: On the day of sow farrowing, colostrum was collected from the nipples of the front, middle and back three positions, 5 mL each, and the samples were stored at -20°C after collection. The content of milk fat, lactose, milk protein, immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) was determined by enzyme-linked immunosorbent assay. The enzyme-linked immunosorbent assay kits for the above six proteins were purchased from Nanjing Jiancheng Bioengineering Research Institute, and the item numbers were: A042-2-1, H405, A045-4-2, H106-1-2, H108-1-2 and H109-1-2.

[0057] Table 2 Effects of adding different feed additives to the basal diet on the composition of sow colostrum

[0058]

[0059]

[0060] As shown in Table 2, compared with the control group, the addition of hydroxytyrosol, theaflavin and the compound of the two to the diet of pregnant sows increased the content of milk protein, milk fat, lactose and immunoglobulin in the colostrum of sows to varying degrees. Compared with the hydroxytyrosol group and the theaflavin group, the hydroxytyrosol group had higher milk protein, milk fat and lactose content, and the theaflavin group had higher immunoglobulin content. The above indicators of the compound group were better than when the two were used alone.

[0061] In summary, the feed additive of the present invention can improve the production and reproduction performance of sows, increase the nutrient content and immunoglobulin content of lactating sows, help provide sufficient nutritional energy to suckling pigs and improve their immune ability, and improve the weight gain effect of suckling pigs and promote their growth.

[0062] 2. Effects of feed additives on growth performance of weaned piglets

[0063] The experiment was conducted in a large-scale breeding farm in Hubei Province. Forty healthy, disease-free, and similar-weight long-distance weaned piglets (Landrace × Large White) were selected and randomly divided into four groups, with two replicates in each group and five pigs in each replicate. The groups were set up as: control group (fed with basal diet), hydroxytyrosol group (0.02% hydroxytyrosol added to the basal diet), theaflavin group (0.02% theaflavin added to the basal diet) and compound group (0.01% hydroxytyrosol and 0.01% theaflavin added to the basal diet). The basal diet for weaned piglets was provided by Jingzhou Haida Co., Ltd. The name of the diet was 881. The amount of addition was 250g / head for piglets weighing 6-8kg, 500g / head for piglets weighing 8-12kg, and 800g / head for piglets weighing 12-20kg. The experimental pigs were arranged in the same pig house. Deworming and immunization were carried out according to the routine procedures and methods of the pig farm before the experiment, and they were free to eat and drink water during the period.

[0064] 2.1. Determination of growth performance related indicators of weaned piglets

[0065] On the first and 21st days of the experiment, the weight of each piglet was recorded. At the same time, the daily feed intake of the piglets was recorded, and the average daily weight gain, average daily feed intake and feed-to-weight ratio of the experimental piglets were calculated. The relevant results are shown in Table 3.

[0066] Table 3 Effects of adding different feed additives to the basic diet on the growth performance of weaned piglets

[0067]

[0068] As shown in Table 3, compared with the control group, the average daily weight gain of the experimental piglets in the hydroxytyrosol group, theaflavin group and the compound group increased by 22.37g, 21.49g and 33.55g, and the feed-to-weight ratio decreased by 0.09, 0.07 and 0.11, respectively. Adding hydroxytyrosol, theaflavin and their compound to the diet of weaned piglets can increase the feed intake of weaned piglets, increase daily weight gain and reduce feed-to-weight ratio, which is beneficial to improve the energy conversion rate of feed and promote the growth of piglets. Adding the compound of the two to the diet has a better effect.

[0069] 2.2. Determination of diarrhea-related indicators

[0070] The diarrhea of ​​the test pigs was observed daily, and the date and severity of diarrhea were recorded in time, and the diarrhea rate and diarrhea index were calculated. Among them, diarrhea rate = diarrhea piglets / (total number of pigs × number of days) × 100%; diarrhea index = sum of fecal scores / total number of test pigs, the higher the index, the more severe the diarrhea. Table 4 shows the diarrhea scoring standard. Table 5 shows the effect of the feed additive of the present invention on piglet diarrhea.

[0071] Table 4 Scoring criteria for diarrhea

[0072]

[0073] Table 5 Effects of adding different feed additives to the basic diet on diarrhea in weaned piglets

[0074]

[0075] As shown in Table 5, compared with the control group, the diarrhea rate and diarrhea index of piglets in the hydroxytyrosol group, theaflavin group and compound group were significantly reduced, and the compound group had a better effect in preventing diarrhea.

[0076] 2.3 Analysis of bacterial flora in the cecum and colon

[0077] On the 21st day of the experiment, fasting for 12h began at 8:00 pm. After anesthesia, all experimental pigs quickly opened the abdominal cavity, took cecum and colon chyme samples, put them into sterilized EP tubes, and stored them at -80 ° C for testing after quick freezing in liquid nitrogen. Take the OMEGA company's bacterial DNA extraction kit (item number D3350-01) and follow the instructions. According to the bacterial 16S rRNA gene sequence, specific primers were designed, with lactobacillus, bifidobacterium and bacillus as common probiotics and Escherichia coli as common pathogens. Taqman probes were used for real-time fluorescence quantitative PCR reactions to explore the effect of the feed additive of the present invention on the intestinal flora of weaned piglets. Primer and probe sequences are shown in Table 6, where F represents upstream primers, R represents downstream primers, and P represents probes.

[0078] Table 6 Real-time fluorescence quantitative PCR primers and probe sequences

[0079]

[0080]

[0081] Real-time fluorescence quantitative PCR detection was performed using SuperReal fluorescence quantitative premix reagent (Cat. No.: FP206-01) from Tiangen Biochemical Technology (Beijing) Co., Ltd. A two-step PCR was used, the reaction system is shown in Table 7, and the reaction procedure was: 95°C pre-denaturation for 15 min, followed by 95°C denaturation for 3 s, 60°C annealing / extension for 25 s, for a total of 40 cycles.

[0082] Table 7 Real-time fluorescence quantitative PCR reaction system for intestinal flora

[0083]

[0084] The Ct value was determined by real-time fluorescence quantitative PCR with each gram of content as the detection unit. The number of copies contained in each sample was calculated by the Ct value and the standard curve. The result was expressed as the common logarithm of the number of bacteria per gram of content, i.e., lg (number of copies / g). The results are shown in Table 8.

[0085] Table 8 Effects of adding different feed additives to the basal diet on the intestinal flora of weaned piglets

[0086]

[0087] As shown in Table 8, compared with the control group, the number of probiotics such as Lactobacillus and Bifidobacterium in the cecum and colon of weaned piglets in the hydroxytyrosol group, theaflavin group and the compound group increased to varying degrees, and the number of pathogenic bacteria such as Escherichia coli decreased. It can be seen that the addition of hydroxytyrosol, theaflavin and their compound to the diet is beneficial to maintaining intestinal health, and the compound group has a better effect.

[0088] In summary, the feed additive of the present invention can greatly alleviate the diarrhea of ​​suckling pigs after weaning, increase the food intake of weaned piglets and improve their feed utilization rate, and is beneficial to regulating their intestinal microecology, improving intestinal health, promoting the growth and reproduction of beneficial bacteria such as lactobacillus, inhibiting the number of pathogenic bacteria such as Escherichia coli, accelerating the growth of piglets, and enhancing the growth and development ability of weaned piglets.

[0089] 3. Effect of feed additives on antibody levels in piglets after immunization

[0090] The grown-up (Landrace × Large White) dual-purpose piglets were selected as experimental animals. Eight litters of piglets were selected, with 8-12 pigs in each litter, and randomly divided into four groups, with two replicates in each group and one litter in each replicate. The groups were set as: control group (fed with creep feed), hydroxytyrosol group (0.02% hydroxytyrosol was added to the creep feed), theaflavin group (0.02% theaflavin was added to the creep feed) and composite group (0.01% hydroxytyrosol and 0.01% theaflavin were added to the creep feed). The feeding experiment spanned the two stages of piglet growth and development, lactation and weaning, from 7 days old to 30 days old, and was specifically divided into two periods: the early stage of creep feed (7-22 days old, lactation) and the late stage of creep feed (22-30 days old, after weaning). The creep feed was provided by Jingzhou Haida Feed Co., Ltd., and the amount of creep feed added in the early stage was 100g / head, and the amount of creep feed added in the late stage was 250g / head.

[0091] The pigs were vaccinated with inactivated circovirus type 2 vaccine (produced by Shandong Huahong Bioengineering Co., Ltd., strain DBN-SX07) at 15 days of age. 14 days after vaccination, 12 pigs in each group were selected for blood sampling, and the antibody level after immunization with circovirus type 2 vaccine was detected using an ELISA kit (purchased from Chongqing Aolong Biological Products Co., Ltd.), and the OD value was calculated. 450 Determine the positive rate of circovirus type 2 antibody. Sample OD 450nm ≤0.3, judged as negative for circovirus type 2 antibody; sample OD 450nm>0.3, it was judged as positive for circovirus type 2 antibody. The antibody levels after circovirus type 2 inoculation are shown in Table 9.

[0092] Table 9 Effects of adding different feed additives to creep feed on the antibody levels of immunized piglets

[0093]

[0094] The above results show that compared with the blank group, the addition of 0.02% hydroxytyrosol or theaflavin in the creep feed slightly increased the content of circovirus type 2 antibodies, and the antibody positive rate increased by 16.7 and 8.4 percentage points respectively. In the combined group with hydroxytyrosol and theaflavin, the serum antibody content and positive rate increased significantly, with the antibody content increasing by 49.1% and the antibody positive rate increasing by 33.4 percentage points.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A feed additive, characterized in that: It comprises hydroxytyrosol and theaflavins in a mass ratio of 0.5-2:

1.

2. The feed additive according to claim 1, characterized in that It includes hydroxytyrosol and theaflavins in a mass ratio of 1:

1.

3. A pig feed, characterized in that: The method comprises the feed additive as described in any one of claims 1 to 2 and a basic feed.

4. The pig feed according to claim 3, characterized in that The feed additive accounts for 0.02% of the total mass of the basic feed.

5. Use of the feed additive according to any one of claims 1 to 2 or the pig feed according to any one of claims 3 to 4 in improving the production performance of sows.

6. The use of the feed additive or pig feed according to claim 5 in improving the production performance of sows, characterized in that: Improving the production performance of sows includes at least one of the following (1)-(2): (1) Increase the weight of lactating piglets; (2) Increasing the content of milk protein, milk fat, lactose and immunoglobulin in sow colostrum, wherein the immunoglobulin includes one or more of IgG, IgA and IgM.

7. Use of the feed additive according to any one of claims 1 to 2 or the pig feed according to any one of claims 3 to 4 in improving the growth performance of weaned piglets.

8. The use of the feed additive or pig feed according to claim 7 in improving the growth performance of weaned piglets, characterized in that: Improving the growth performance of weaned piglets includes at least one of the following (1)-(5): (1) Increase the feed intake of weaned piglets; (2) Improve the daily weight gain of weaned piglets; (3) Reduce the feed-to-weight ratio of weaned piglets; (4) Reduce the diarrhea rate and diarrhea index of weaned piglets; (5) Improve the intestinal flora of weaned piglets, including increasing the number of Lactobacillus, Bifidobacterium and Bacillus and reducing the number of Escherichia coli.

9. Use of the feed additive according to any one of claims 1 to 2 or the pig feed according to any one of claims 3 to 4 in improving the antibody level of piglets after vaccination.

10. The use of the feed additive or pig feed according to claim 9 in improving the antibody level of piglets after vaccination, characterized in that: Improving the antibody level of piglets after vaccination includes at least one of the following (1)-(2): (1) Increase serum antibody levels after vaccination with inactivated circovirus type 2 vaccine; (2) Improve the antibody positivity rate after vaccination with inactivated circovirus type 2 vaccine.

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