CN114794309A

CN114794309A - Feed additive containing acidifying agent and preparation method and application thereof

Info

Publication number: CN114794309A
Application number: CN202210618684.6A
Authority: CN
Inventors: 殷军; 欧锦强
Original assignee: Jiangsu Wing Biotech Co ltd
Current assignee: Jiangsu Wing Biotech Co ltd
Priority date: 2022-06-01
Filing date: 2022-06-01
Publication date: 2022-07-29
Anticipated expiration: 2042-06-01
Also published as: CN114794309B

Abstract

The application relates to the technical field of feed additives, in particular to a feed additive containing an acidifier and a preparation method and application thereof. The feed additive containing the acidifying agent comprises a core body and a slow-release coating layer arranged outside the core body, wherein the core body and the slow-release coating layer are compounded into a whole through irradiation treatment; the core body comprises the following components in parts by weight: 50-80 parts of an acidifier, 20-30 parts of polycaprolactone and 30-40 parts of a disintegrant; the slow release coating layer comprises the following components in parts by weight: 60-80 parts of polyhydroxybutyrate, 20-30 parts of polyethylene glycol, 5-15 parts of an acidifier and 5-10 parts of trehalose. The feed additive has good slow release effect in gastric juice and intestinal tract, is helpful for improving biological immunity, has small dosage in feed formula and good acidification effect on gastric juice and intestinal tract, and can effectively improve the use convenience of the acidifier in feed.

Description

Feed additive containing acidifying agent and preparation method and application thereof

Technical Field

The application relates to the technical field of feed additives, in particular to a feed additive containing an acidifier and a preparation method and application thereof.

Background

In pet feeding, antibiotics are widely added into pet feed due to the characteristics of effectively preventing infection of pathogenic bacteria in the intestinal tract of pets and promoting healthy growth of pets. However, the abuse of antibiotics has become a major risk for affecting the health of pets, and the reduction and even replacement of antibiotics in pet feed is of great significance to the health of pets at present. Researches show that the pH value in the intestinal tract of animals has great significance for inhibiting pathogenic bacteria, so that the acidifying agent used in the feed industry for changing the pH value in the intestinal tract of animals and improving the immunity has become a common method.

At present, the commonly used acidifier enters the body of the pet along with the feed, most of the acidifier is decomposed, digested and absorbed in gastric juice, and only a small part of the acidifier can enter the intestinal tract to play a role in acidifying the intestinal tract. In order to acidify the intestinal tract, the feed is often added with a quantity of acidifier which is several times more than the actual required quantity, but the excessive acidifier can greatly improve the acidity of the feed and destroy other nutritional ingredients in the feed.

Disclosure of Invention

The feed additive has good slow-release effect in gastric juice and intestinal tracts, is beneficial to improving the biological immunity, has a small dosage in a feed formula, has excellent acidification effect on the gastric juice and the intestinal tracts, and can effectively improve the use convenience of the acidifier in the feed.

In a first aspect, the application provides an acidulant-containing feed additive, which comprises a core body and a slow-release coating layer arranged outside the core body, wherein the core body and the slow-release coating layer are compounded into a whole through irradiation treatment;

the core body comprises the following components in parts by weight: 50-80 parts of an acidifying agent, 20-30 parts of polycaprolactone and 30-40 parts of a disintegrating agent; the slow release coating layer comprises the following components in parts by weight: 60-80 parts of polyhydroxybutyrate, 20-30 parts of polyethylene glycol, 5-15 parts of an acidifier and 5-10 parts of trehalose.

In the core body of this application, utilize polycaprolactone to adhere acidifying agent and disintegrant together, polycaprolactone has good biocompatibility, it can regard as the braced frame of acidifying agent and disintegrant, make acidifying agent and disintegrant adhere to and exist certain molecular gap on braced frame, recycle the disintegrant as the carrier, not only can cooperate with polycaprolactone to accelerate the acidifying agent to take place to disintegrate, can also reduce the addition of other carrier components and increase the coating amount, feed additive's manufacturing cost has been reduced to a certain extent.

In the slow-release coating layer, polyhydroxybutyrate has good biocompatibility with animals, polyhydroxybutyrate is used as a coating main material, and compared with other coating materials, the slow-release coating layer can still provide a good support frame for an acidifier in an intestinal tract, so that the acidifier is slowly released in the intestinal tract delivery and can play an acidification role for a long time. Polyethylene glycol is used as a coating auxiliary material, and the acidifier and the trehalose can be stably adhered in the polyhydroxybutyrate under the action of the polyethylene glycol to form a stable and uniform sustained-release coating layer.

In addition, if the structure of the sustained-release coating layer is easy to crack and disintegrate, the acidifying agent in the core body inside the sustained-release coating layer loses coating and is rapidly dispersed, so that the sustained release of the acidifying agent cannot be realized; if the structure of the slow-release coating layer is too firm, the acidifier in the core body inside the slow-release coating layer is difficult to effectively release, so that the utilization rate of the acidifier is easily reduced. Therefore, the structure of the sustained-release coating layer should not be too fragile or too firm to achieve sustained release of the acidifying agent. This application adopts irradiation treatment, can make polycaprolactone and polyhydroxybutyrate take place the cross-linking, make the core body and sustained-release coating layer take place to bond in handing-over department, effectively improve the fragility of polyhydroxybutyrate of handing-over department, thereby improved shell structure's stability to a certain extent, make sustained-release coating layer take place to disintegrate at the disintegrant in-process that has a slow fracture, and sustained-release coating layer still can keep good braced frame before totally disintegrating not, from this can realize the slowly-releasing of acidifying agent better.

After the feed additive enters an animal body, the acidifier and the trehalose in the slow-release coating layer have good water solubility, but the release speed of the acidifier is slowed down due to the fact that the acidifier is embedded in the polyhydroxybutyrate, so that the situation that the acidifier is excessively and quickly released to damage gastric mucosa can be avoided, the trehalose can further protect the gastric mucosa, the biological immunity is improved, and the gastric environment is gradually improved. The core body can better keep stability in gastric juice under the coating of the slow-release coating layer, and enough acidifier is reserved for the intestinal tract to improve the intestinal tract acidification effect.

After the slow-release coating layer is soaked in gastric juice and conveyed to an intestinal tract, even pores and cracks are left after the acidifier and the trehalose on the slow-release coating layer are exhausted, so that water in the intestinal tract can conveniently enter the core body, the disintegrant still maintains a supporting frame after absorbing water, and the acidifier in the core body can only be slowly extruded out of the slow-release coating layer through the pores and the cracks by the disintegrant. In the conveying process, polyhydroxybutyrate and polycaprolactone can also be used as carbon sources of a microbial system in an animal body, so that the balance of intestinal flora is promoted, and the biological immunity is improved. Even if the intestinal flora cannot digest the frame formed by the polyhydroxybutyrate and the polycaprolactone in time, the intestinal flora can be converted into excrement to be discharged out of the animal body and further degraded by in-vitro microorganisms, and the intestinal flora has good environmental friendliness.

In conclusion, the feed additive disclosed by the application can enable the acidifier of the slow-release coating layer to enter gastric juice to improve the gastric environment, and enable the acidifier of the core body to enter the intestinal tract to improve the intestinal environment, so that the feed additive has a good slow-release effect in the gastric juice and the intestinal tract, is beneficial to improving the biological immunity, is small in dosage in a feed formula, has a good acidification effect on the gastric juice and the intestinal tract, and can effectively improve the use convenience of the acidifier in the feed.

Preferably, the weight ratio of the core body to the sustained release coating layer is (6-8) to (1-3).

By adopting the technical scheme, if the dosage of the slow-release coating layer is too much, the acidifier in the core body is difficult to effectively release, and the weight ratio is preferably used in the application.

Preferably, the acidulant is a mixture of one or more of citric acid, fumaric acid, lactic acid, malic acid, sorbic acid, formic acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid and hydrochloric acid.

Preferably, the acidifier comprises the following components in parts by weight: 10-20 parts of citric acid, 10-20 parts of fumaric acid, 8-15 parts of sorbic acid, 1-5 parts of propionic acid and 1-5 parts of hydrochloric acid.

Preferably, the acidifier comprises the following components in parts by weight: the weight ratio of the citric acid, the fumaric acid, the sorbic acid, the propionic acid and the hydrochloric acid is 5:5:2:1: 1.

By adopting the technical scheme, the acidifier can select organic acid, inorganic acid or mixed acid compounded by the organic acid and the inorganic acid, wherein the citric acid, the fumaric acid, the lactic acid, the malic acid, the sorbic acid, the formic acid, the acetic acid and the propionic acid are organic acids, and the phosphoric acid, the sulfuric acid and the hydrochloric acid are inorganic acids, and are commonly used acidifiers in animal feeds, so that the acidifier is wide in source and excellent in acidification effect. In the present application, further preferred acidulants comprise the following components in parts by weight: 10-20 parts of citric acid, 10-20 parts of fumaric acid, 8-15 parts of sorbic acid, 1-5 parts of propionic acid and 1-5 parts of hydrochloric acid, which cover organic acid and inorganic acid, can effectively improve the average daily gain of animals in the feed additive system of the application, and indirectly shows that the feed additive system can effectively improve the acidification effect of gastric juice and intestinal tracts so as to better absorb nutrition and improve the biological immunity of the animals. Tests show that the acidulant is further preferably prepared by mixing citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid in a weight ratio of 5:5:2:1: 1.

Preferably, the disintegrant is one or more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, cross-linked polyvinylpyrrolidone and cross-linked sodium carboxymethyl cellulose.

By adopting the technical scheme, the sodium carboxymethyl starch, the low-substituted hydroxypropyl cellulose, the cross-linked polyvinylpyrrolidone and the cross-linked sodium carboxymethyl cellulose have good water absorption and can provide a good loading effect for the acidifying agent.

In a second aspect, the present application provides a method for preparing an acidulant-containing feed additive, comprising the steps of: preparation of core body material: heating polycaprolactone to be molten, adding an acidifying agent, adding a disintegrating agent after uniformly stirring, continuously stirring until the materials are uniformly dispersed, quickly cooling, and grinding into powder to obtain a core body material;

preparing a slow-release coating solution: dissolving polyhydroxybutyrate in chloroform to obtain a polyhydroxybutyrate-chloroform solution, dissolving polyethylene glycol, an acidifier and trehalose in ethanol to form a mixed solution, and uniformly mixing the polyhydroxybutyrate-chloroform solution and the mixed solution to obtain a slow-release coating solution;

coating and granulating: adding the core body material into the slow-release coating liquid for coating, preparing coating powder by a spray granulation method, and then performing irradiation treatment to prepare the feed additive.

When the slow-release coating solution is prepared, the polyhydroxybutyrate is dissolved by using chloroform, the polyethylene glycol, the acidifier and the trehalose are dissolved by using ethanol, and the chloroform and the ethanol are mutually dissolved to realize uniform mixing of all components to form a uniform and stable slow-release coating solution; this application is for realizing the cladding, when preparing the core body material, earlier polycaprolactone heat and melt, be convenient for stir and make acidifier adhesion on the disintegrant in the acidifier, polycaprolactone wherein acts together with the disintegrant, can reduce the acidifier in the core body and dissolve in the ethanol of slowly-releasing coating liquid, the feed additive that from this can form has intact nucleocapsid structure in order to guarantee its good slowly-releasing action, make acidifier in slowly-releasing coating layer and the core body have a concentration difference simultaneously, the acidifier in the casing of being convenient for slowly releases. The spray granulation method is beneficial to rapid volatilization of chloroform and ethanol in the slow-release coating liquid in the granulation process, effectively reduces the residual quantity of the chloroform and the residual quantity of the ethanol in the feed additive, and ensures the safety of the feed additive.

Preferably, the core body material and the slow release coating liquid are coated by homogenizing or ultrasonic treatment.

By adopting the technical scheme, the sustained-release coating liquid can be promoted to be uniformly dispersed around the core body material by homogenizing and ultrasonic treatment to coat the core body material, so that the feed additive with uniform coating is obtained.

Preferably, when the core body material and the slow-release coating liquid are coated, air suction treatment is continuously performed.

By adopting the technical scheme, volatile chloroform and ethanol can be removed in time through air exhaust treatment, so that polyhydroxybutyrate, polyethylene glycol, an acidifier and trehalose are stably coated outside the core to form the slow-release coating liquid.

In a third aspect, the present application provides a pet food comprising said feed additive.

In summary, the present application has the following beneficial effects:

1. the feed additive has good slow release effect in gastric juice and intestinal tracts, is beneficial to improving the biological immunity, has small dosage in the feed formula and excellent acidification effect on the gastric juice and the intestinal tracts, and can also effectively improve the use convenience of an acidifier in the feed.

2. Specific acidifier is selected for use in this application, and it is comparatively stable in the feed additive system of this application, can realize the slow-release effect better.

3. According to the method, the acidifying agent and the disintegrating agent are bonded into a core body material by polycaprolactone, the polyhydroxybutyrate is compatible with polyethylene glycol, the acidifying agent and trehalose by using chloroform and ethanol, the prepared slow-release coating liquid can coat the core body material well, and the chloroform and the ethanol are removed by a spray granulation method, so that the prepared feed additive coating is stable and uniform in structure, and the slow-release effect in gastric juice and intestinal tracts can be met.

Detailed Description

Source of raw materials

The raw materials involved in the embodiments of the present application are all commercially available products. Wherein, PHB is taken as an example to illustrate the polyhydroxybutyrate, which is purchased from Pasteur and has the mark of 1001 MD; the polyethylene glycol is exemplified by PEG-4000.

The present application will be described in further detail with reference to examples and comparative examples.

Examples

Example 1

A feed additive containing an acidifying agent comprises a core body and a slow-release coating layer arranged outside the core body, and the preparation method comprises the following steps:

firstly, preparation of core material

Weighing 156g of polycaprolactone, placing at 70 ℃ (allowing fluctuation in the temperature range of 60-80 ℃) and heating until the polycaprolactone is melted, adding 406g of acidifying agent, stirring uniformly, adding 188g of disintegrating agent, continuing stirring until the materials are uniformly dispersed, cooling at the speed of 10 ℃/s, grinding into powder, and sieving with a 100-mesh sieve to obtain a core body material for forming the shell;

wherein the acidulant is prepared by mixing citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid according to the weight ratio of 5:5:2:1: 1; the disintegrant may be one or a mixture of more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, cross-linked polyvinylpyrrolidone, and cross-linked sodium carboxymethyl cellulose, which is exemplified by sodium carboxymethyl starch in this embodiment;

② preparation of slow-release coating liquid

Dissolving 146g of PHB in 500mL of chloroform to prepare a PHB-chloroform solution, dissolving 61g of PEG-4000, 24g of acidifying agent and 19g of trehalose in 250mL of ethanol to form a mixed solution, wherein the proportion of the acidifying agent is the same as that of the acidifying agent in the core body material, the using amount of the chloroform and the ethanol can be increased or decreased according to the dissolving condition of the materials, and then putting the PHB-chloroform solution and the mixed solution into a coating tank to be uniformly mixed to prepare a slow-release coating solution for forming a slow-release coating layer;

(iii) coating and granulating

Adding the core body material into the slow-release coating liquid, stirring at a stirring speed of 350rpm for 10min at a mass ratio of 3:1, homogenizing for 2 times (30 s each time) during the period, continuously extracting gas in a coating tank during stirring, keeping the gas pressure in the coating tank at 0.5-0.8 atmospheric pressure, after coating, preparing coating powder by a spray granulation method, and irradiating the coating powder by electron beams with a radiation dose of 15kGy (allowed to fluctuate within the range of 12-18 kGy) to prepare the feed additive.

Examples 2 to 4

Examples 2-4 the amounts of the core body and the components of the sustained release coating layer were adjusted based on the procedure of example 1, as shown in table one below.

TABLE-dosage adjustment Table for examples 1-4 (unit g)

Comparative example

Comparative example 1

The feed additive of this comparative example was directly the acidulant of example 1.

Comparative example 2

This comparative example replaces the polycaprolactone in the core body with beeswax based on the components and method of example 1.

Comparative example 3

This comparative example replaces polyhydroxybutyrate with hydroxypropylmethylcellulose phthalate (HPMCP) based on the components and process of example 1.

Comparative example 4

This comparative example was based on the composition and method of example 1 and was not subjected to irradiation treatment.

Comparative example 5

In the comparative example, on the basis of the components and the method in the embodiment 1, the PHB in the slow-release coating layer is replaced by a mixture of the PHB and the polycaprolactone, and the weight ratio of the PHB to the polycaprolactone is 1: 1.

Comparative example 6

This comparative example replaces the disintegrant with zeolite powder based on the components and method of example 1.

Performance testing

(1) Test for moisture resistance

The feed additives prepared in examples 1 to 4 and comparative examples 1 to 6 were used as samples, and the water content (%) of the samples in an environment of 40 ℃ and 75% humidity was measured, and the test results are shown in the following Table II.

TABLE II Water content (unit:%) in examples 1 to 4 and comparative examples 1 to 6

Test group	Day 1	Day 7	Day 14	Day 28
					Example 1	3.02	3.10	3.21	3.35
Example 2	3.02	3.09	3.23	3.36
					Example 3	3.07	3.15	3.27	3.39
Example 4	3.05	3.12	3.24	3.35
					Comparative example 1	3.05	5.61	6.68	8.39
Comparative example 2	3.07	3.20	3.41	3.56
					Comparative example 3	3.07	3.15	3.23	3.44
Comparative example 4	3.06	3.18	3.39	3.52
					Comparative example 5	3.01	3.06	3.17	3.22
Comparative example 6	3.03	3.10	3.20	3.35

With reference to table two, examples 1 to 4 are feed additives prepared from different raw materials, and the feed additives are tested in an environment with a temperature of 40 ℃ and a humidity of 75% for 28 days, and the increased moisture content is lower and obviously reduced compared with that of the comparative document 1, so that the feed additives prepared by the method have better moisture resistance, are more convenient to transport and store, and are helpful for improving the convenience of the acidulant in the feed to a certain extent. In addition, the feed additives prepared in comparative examples 2 to 4 are more easily moisture-absorbed, and the feed additive prepared in comparative example 5 has better moisture-proof property, which may be caused by the fact that the feed additives prepared in comparative examples 2 to 4 are difficult to cross-link at the hinge of the sustained-release coating layer and the core body, and moisture is easily absorbed by the hydrophilic component in the sustained-release coating layer to cause moisture absorption; the feed additive prepared in the comparative example 5 directly and completely crosslinks the slow-release coating layer, so that the structure of the slow-release coating layer is more stable, and the difficulty of water absorption into the slow-release coating layer and water penetration into the core is increased. The feed additive of comparative example 6, in which the disintegrant was replaced, had little effect on the moisture resistance, and it was found that the sustained-release coating layer of the present application was sufficient to have a good coating effect on the core body component.

(2) Test of gastric fluid release and intestinal fluid release artificial gastric fluid: taking 16.4mL of dilute hydrochloric acid, adding about 800mL of water and 10g of pepsin, uniformly shaking, and adding water to dilute into 1000mL to obtain the compound preparation; the artificial intestinal juice is phosphate buffer (containing pancreatin) (pH6.8).

The feed additives prepared in examples 1 to 4 and comparative examples 1 to 6 were used as samples, and the samples were subjected to a gastric fluid release degree test and an intestinal fluid release degree test in this order using an artificial gastric fluid and an artificial intestinal fluid. Specifically, the dissolution rate (%) at different times is determined by adopting a third method of a method for determining the dissolution rate and the release rate of 0931 in the fourth part of the Chinese pharmacopoeia, and the test results are shown in the third table below.

TABLE III dissolution rates (unit:%) of examples 1 to 4 and comparative examples 1 to 6

In combination with table three, in the dissolution tests of examples 1 to 4, the dissolution rate and dissolution time of the acidulant are approximately linearly increased, and compared with comparative example 1, the acidulant in the feed additive of the present application can be slowly and orderly released, so that cytotoxicity is reduced, and meanwhile, the acidification time of the feed additive is effectively prolonged.

Compared with comparative examples 2-4, the dissolution rate of the feed additive reaches over 90% after the feed additive is treated in the artificial intestinal juice for 6 hours, wherein the dissolution rate of example 3 is obviously higher than that of example 1. This is probably because when the polycaprolactone in the core body is replaced by a binder such as beeswax (comparative example 2) or the core body and the sustained-release coating layer are not subjected to radiation treatment (comparative example 4), polyhydroxybutyrate in the sustained-release coating layer is not crosslinked and is easily cracked and disintegrated, so that a stable support frame is difficult to provide for the core body, and the acidifying agent is released in advance; if polyhydroxybutyrate in the slow-release coating layer is replaced by other coating materials (comparative example 3), the polyhydroxybutyrate is dissolved when entering intestinal fluid, and the acidifier is released in a large amount, so that the slow-release effect is difficult to realize in the intestinal fluid. The slow-release coating layer of the comparative example 5 contains polyhydroxybutyrate and polycaprolactone at the same time, and the irradiation treatment can complete the crosslinking of the whole coating layer, so that the core-shell structure of the obtained feed additive is too firm, and the acidifying agent in the core body is difficult to completely release.

Therefore, Polyhydroxybutyrate (PHB) is used as a coating main material of the slow-release coating layer in the application, polycaprolactone in a core body is matched, only the junction of the slow-release coating layer and the core body is crosslinked after irradiation treatment, the stability of a core-shell structure can be increased to a certain extent, the slow-release coating layer can have a gradual cracking process in intestinal juice, the slow release of an acidifier in gastric juice and intestinal juice can be realized, and the high final dissolution rate (the dissolution rate of the artificial intestinal juice is 8 hours) of the acidifier is also ensured.

In addition, in comparative example 6, because no disintegrant is added, the acidifying agent in the core body lacks the power of outward extrusion, the dissolution rate is greatly reduced, a large amount of the acidifying agent is still not released after the artificial intestinal juice is treated for 8 hours, and the acidifying agent is easily discharged out of the body without being utilized, so that the bioavailability of the feed additive is low.

Therefore, the feed additive has the advantages of excellent acidification effect, long sustained-release period, high bioavailability and the like only by compounding the components of the core and the sustained-release coating layer into a whole after being matched with each other, and the dosage of the feed additive in a feed formula can be reduced.

(3) Experimental animal effect test

The test is 3 months to 4 months from 2022 years, 110 young mice with good health status and weight difference within 2g are selected and randomly divided into 11 groups, which correspond to examples 1 to 4, comparative examples 1 to 5 and blank control respectively, wherein the basic ration is commercial mouse ration, the feeding period is 20 days, the feeding conditions of each group are shown in the following table four, the feed conversion ratio (average daily food consumption/average daily gain) of each group of mice is determined, and the determination results are shown in the following table five.

Feeding condition table

Test group	Addition scheme
		1	9g basal diet +1g feed additive of example 1
2	9g basal diet +1g feed additive of example 2
		3	9g basal diet +1g feed additive of example 3
4	9g basal diet +1g feed additive of example 4
		5	9g basal diet +1g feed additive of comparative example 1
7	9g basal diet +1g feed additive of comparative example 2
		8	9g basal diet +1g feed additive of comparative example 3
9	9g basal diet +1g feed additive of comparative example 4
		10	9g basal diet +1g feed additive of comparative example 5
6	9g basal diet +1g feed additive of comparative example 6
		11	10g basal diet

Table five feed-meat ratios of mice of examples 1-4, comparative examples 1-6 and blank control

	Average daily gain/g/d	Average daily food intake/g/d	Meat ratio of materials
				Example 1	1.33	5.25	3.95
Example 2	1.25	5.06	4.05
				Example 3	1.29	5.13	3.98
Example 4	1.18	5.05	4.28
				Comparative example 1	0.95	5.27	5.55
Comparative example 2	1.14	5.25	4.61
				Comparative example 3	1.03	4.99	4.84
Comparative example 4	1.10	5.24	4.76
				Comparative example 5	0.97	5.02	5.18
Comparative example 6	0.91	5.11	5.62
				Blank control	0.78	4.72	6.05

By combining table four and table five, the feed additives of examples 1-4 of the present application (relative to the blank control group) can significantly increase the average daily food intake and average daily gain of mice, and significantly reduce the feed-meat ratio. The lower the feed meat ratio, the more the feed is converted into energy which is absorbed and utilized by the mice, so that the feed additive can promote the appetite of the animals and effectively improve the bioavailability of the feed. In comparative examples 1 to 6, although comparative example 1 had an average daily food intake similar to that of example 1, the average daily gain was low, and the meat of the meat was obtained at a higher meat/meat ratio than that of the present application; the average daily food intake and average daily gain weight of comparative examples 2 to 6 were lower than those of the present application, and the feed-meat ratio was also higher than that of the present application, so that the feed additive of the present application had a higher effect of promoting the improvement of the feed utilization.

In summary, the feed additive of example 1 has good moisture resistance, good convenience in use, excellent sustained release effect in gastric juice and intestinal juice, and low feed-meat ratio, so that the feed additive of example 1 is a preferred example.

Examples 5 to 9

Examples 5-9 the weight ratio of the core body to the sustained release coating layer was adjusted based on the method and components of example 1, as shown in table six below.

TABLE sixty weight ratios of core body to sustained release coating layers of examples 1 and 5-9

	Weight ratio of
		Example 1	3:1
Example 5	9:1
		Example 6	8:1
Example 7	6:1
		Example 8	4:1
Example 9	2:1

The feed additives prepared in the above examples 5 to 9 were subjected to the above moisture absorption test, gastric fluid release test and intestinal fluid release test, and experimental animal effect test, and the test results thereof are shown in tables seven to nine.

TABLE seventhly Water contents (unit:%)

Test group	Day 1	Day 7	Day 14	Day 28
					Example 1	3.02	3.10	3.21	3.35
Example 5	3.04	3.21	3.33	3.46
					Example 6	3.02	3.18	3.29	3.43
Example 7	3.02	3.15	3.25	3.40
					Example 8	3.02	3.11	3.21	3.37
Example 9	3.02	3.08	3.15	3.34

TABLE VIII dissolution rates (unit:%) of examples 1, 5 and 9

TABLE nine mean values of weight gain in mice corresponding to examples 1, 5-9

	Average daily gain/g/d	Average daily food intake/g/d	Meat ratio of materials
				Example 1	1.33	5.25	3.95
Example 5	1.26	5.12	4.06
				Example 6	1.27	5.14	4.05
Example 7	1.30	5.19	3.99
				Example 8	1.33	5.21	3.92

With the combination of the seven tables to the nine tables, the feed additive can slow down the moisture absorption condition along with the increase of the proportion of the slow-release coating layer, and can reduce the dissolution efficiency of the acidifier in gastric juice and intestinal juice to a certain extent. In the experimental animal effect test, the average daily feed intake of animals is increased along with the increase of the proportion of the slow-release coating layer, but the average daily gain is reduced, probably because the slow-release coating layer with large proportion contains more acidifier to promote the appetite of the animals, but because the proportion of the core in the feed addition is correspondingly reduced, the acidifier entering the intestinal tract can be rapidly disintegrated, the intestinal juice is difficult to be continuously and stably acidified, and the meat ratio of the animals is higher. In the above embodiment, the overall effect of embodiment 1 is the most excellent, and therefore it is taken as a preferred embodiment.

Examples 10 to 14

Examples 10-14 were prepared by adjusting the ratio of the acidulant based on the ingredients and method of example 1, as shown in Table ten below.

TABLE Ten ingredient tables (unit: parts) of the acidulants of examples 1, 10-14

Examples	1	10	11	12	13	14
							Citric acid	15	10	20	15	15	3
Fumaric acid	15	10	20	15	15	15
							Sorbic acid	10	8	15	10	10	15
Propionic acid	3	1	5	/	3	10
							Malic acid	/	/	/	3	/	/
Hydrochloric acid	3	1	5	3	/	3
							Phosphoric acid	/	/	/	/	3	/

The feed additives prepared in the above examples 10 to 14 were subjected to the above moisture absorption test, the test of gastric juice release rate and intestinal juice release rate, and the test of the effect of the experimental animals, wherein the adjustment of the catalyst had little influence on the moisture absorption performance and dissolution rate, and no further development was made herein, and the results of the test of the effect of the experimental animals are shown in the following table eleven.

TABLE eleven mean values of body weight gain in mice corresponding to examples 1, 10-14

	Average daily gain/g/d	Average daily food intake/g/d	Meat ratio of materials
				Example 1	1.33	5.25	3.95
Example 10	1.21	5.17	4.27
				Example 11	1.26	5.19	4.12
Example 12	1.15	5.20	4.52
				Example 13	1.13	5.21	4.61
Example 14	1.12	5.15	4.60

In the feed additive of the present application, with reference to table eleven, the definition "acidulant" includes the following components in parts by weight: 10-20 parts of citric acid, 10-20 parts of fumaric acid, 8-15 parts of sorbic acid, 1-5 parts of propionic acid and 1-5 parts of hydrochloric acid, the feed additive covers organic acid and inorganic acid, can effectively improve the average daily weight gain of animals in the feed additive system, and indirectly shows that the feed additive can effectively improve the acidification effect of gastric juice and intestinal tracts so as to better absorb nutrition and improve the biological immunity of the animals. Further preferred is an acidulant comprising citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid in a weight ratio of 5:5:2:1:1 (example 1).

Example 15

This example replaces the homogenization of the coated plasmid with sonication for 20min based on the components and method of example 1. The performance of the prepared feed additive is similar to that of example 1, and the sustained-release coating liquid can be promoted to be uniformly dispersed around the core body material by adopting homogenization and ultrasonic treatment to coat the core body material, so that the feed additive with uniform coating is obtained.

In conclusion, the feed additive disclosed by the application has good slow-release effect in gastric juice and intestinal tracts, is beneficial to improving the biological immunity, is small in dosage in a feed formula, has excellent acidification effect on the gastric juice and the intestinal tracts, and can effectively improve the use convenience of an acidifier in the feed.

The specific embodiments are only for explaining the present application and are not limiting to the present application, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but all the embodiments are protected by patent law within the scope of the claims of the present application.

Claims

1. The feed additive containing the acidifying agent is characterized by comprising a core body and a slow-release coating layer arranged outside the core body, wherein the core body and the slow-release coating layer are compounded into a whole through irradiation treatment;

the core body comprises the following components in parts by weight: 50-80 parts of an acidifier, 20-30 parts of polycaprolactone and 30-40 parts of a disintegrant;

the slow release coating layer comprises the following components in parts by weight: 60-80 parts of polyhydroxybutyrate, 20-30 parts of polyethylene glycol, 5-15 parts of an acidifier and 5-10 parts of trehalose.

2. The feed additive of claim 1, wherein: the weight ratio of the core body to the slow-release coating layer is (6-8) to (1-3).

3. The feed additive of claim 1, wherein: the acidulant is one or more of citric acid, fumaric acid, lactic acid, malic acid, sorbic acid, formic acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid and hydrochloric acid.

4. The feed additive of claim 3, wherein: the acidifier comprises the following components in parts by weight: 10-20 parts of citric acid, 10-20 parts of fumaric acid, 8-15 parts of sorbic acid, 1-5 parts of propionic acid and 1-5 parts of hydrochloric acid.

5. The feed additive of claim 1, wherein: the acidifier comprises the following components in parts by weight: the weight ratio of the citric acid, the fumaric acid, the sorbic acid, the propionic acid and the hydrochloric acid is 5:5:2:1: 1.

6. The feed additive of claim 1, wherein: the disintegrating agent is one or more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, cross-linked polyvinylpyrrolidone and cross-linked sodium carboxymethyl cellulose.

7. A process for the preparation of a feed additive according to any one of claims 1 to 6, comprising the steps of:

preparation of core body material: heating polycaprolactone to be molten, adding an acidifier, adding a disintegrating agent after uniformly stirring, continuously stirring until the materials are uniformly dispersed, quickly cooling, and grinding into powder to obtain a core body material;

8. The method of claim 1, wherein: the core body material and the slow release coating liquid are coated by homogenizing or ultrasonic treatment.

9. The method of claim 1, wherein: and when the core body material and the slow-release coating liquid are coated, continuously performing air exhaust treatment.

10. A pet food, characterized in that: comprising a feed additive according to any one of claims 1 to 6.