CN114794309B

CN114794309B - Feed additive containing acidulant and preparation method and application thereof

Info

Publication number: CN114794309B
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: 2023-07-28
Anticipated expiration: 2042-06-01
Also published as: CN114794309A

Abstract

The application relates to the technical field of feed additives, in particular to a feed additive containing an acidulant and a preparation method and application thereof. The feed additive containing the acidulant comprises a nucleus body and a slow-release coating layer arranged on the outer side of the nucleus body, wherein the nucleus body and the slow-release coating layer are combined into a whole through irradiation treatment; the nucleus comprises the following components in parts by weight: 50-80 parts of acidulant, 20-30 parts of polycaprolactone and 30-40 parts of 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 acidulant and 5-10 parts of trehalose. The feed additive has good slow release effect in gastric juice and intestinal tracts, is beneficial to improving biological immunity, has small dosage in a feed formula, has good acidification effect on gastric juice and intestinal tracts, and can effectively improve the use convenience of the acidulant in feeds.

Description

Feed additive containing acidulant 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 acidulant and a preparation method and application thereof.

Background

In pet feeding, antibiotics are widely added into pet feeds because of the characteristics of effectively preventing infection of intestinal pathogenic bacteria of pets and promoting healthy growth of pets. However, the abuse of antibiotics has become an important hidden trouble affecting the health of pets, and the reduction of antibiotics in pet feeds, even substitution of antibiotics in pet feeds, is significant for the health of pets. Studies have shown that pH in the animal intestinal tract is important for the inhibition of pathogenic bacteria, and therefore, the use of acidulants to alter pH in the animal intestinal tract to enhance immunity has become a common approach in the feed industry.

The conventional acidulant enters the body of the pet along with the feed, most of the acidulant is decomposed, digested and absorbed in gastric juice, and only a small part of the acidulant can enter intestinal tracts to acidify the intestinal tracts. In order to achieve the aim of acidifying the intestinal tract, the feed is often added with a few times more acidulant than the actual needed amount, but the excessive acidulant can greatly improve the acidity of the feed and destroy other nutritional ingredients in the feed.

Disclosure of Invention

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

In a first aspect, the present application provides a feed additive comprising an acidulant, comprising a core and a slow release coating layer disposed on the outer side of the core, wherein the core and the slow release coating layer are combined into a whole by irradiation treatment;

the nucleus comprises the following components in parts by weight: 50-80 parts of acidulant, 20-30 parts of polycaprolactone and 30-40 parts of 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 acidulant and 5-10 parts of trehalose.

In the nuclear body, the acidulant and the disintegrating agent are adhered together by utilizing the polycaprolactone, the polycaprolactone has good biocompatibility and can be used as a supporting frame of the acidulant and the disintegrating agent, the acidulant and the disintegrating agent are adhered to the supporting frame and have a certain molecular gap, and the disintegrating agent is used as a carrier, so that the acidulant can be quickened by being matched with the polycaprolactone, the addition of other carrier components can be reduced, the coating amount is increased, and the production cost of the feed additive is reduced to a certain extent.

In the slow-release coating layer, polyhydroxybutyrate has good biocompatibility with animal bodies, and compared with other coating materials, polyhydroxybutyrate is used as a coating main material, and can still provide a good supporting frame for the acidulant in intestinal tracts, so that the acidulant can be slowly released in the intestinal tracts to exert the acidulation effect for a long time. Polyethylene glycol is used as a coating auxiliary material, and the acidulant and the trehalose can be stably adhered to polyhydroxybutyrate under the action of the polyethylene glycol to form a stable and uniform slow-release coating layer.

In addition, if the structure of the slow-release coating layer is easy to crack and disintegrate, the acidulant in the inner core body of the slow-release coating layer can lose coating and rapidly disperse, and the slow release of the acidulant can not be realized; if the structure of the slow-release coating layer is too stable, the acidulant in the inner core is difficult to release effectively, and the utilization rate of the acidulant is easy to be reduced. Therefore, to achieve slow release of the acidulant, the structure of the slow release coating should not be too fragile or too stable. According to the preparation method, irradiation treatment is adopted, polycaprolactone and polyhydroxybutyrate can be crosslinked, the junction of the core body and the slow-release coating layer is bonded, the brittleness of polyhydroxybutyrate at the junction is effectively improved, the stability of a shell structure is improved to a certain extent, the slow-release coating layer is disintegrated in a slow disintegration process when the disintegrating agent is disintegrated, and a good supporting frame can be kept on the slow-release coating layer before the slow-release coating layer is not disintegrated completely, so that the slow release of the acidifier can be well realized.

After the feed additive enters an animal body, the acidulant and the trehalose in the slow-release coating layer have good water solubility, but the release speed of the feed additive is slowed down due to embedding in polyhydroxybutyrate, so that the damage to gastric mucosa caused by excessive and too fast release of the acidulant 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 wrapping of the slow-release coating layer, and the sufficient acidulant is reserved for the intestinal tract so as to improve the intestinal tract acidulation effect.

After the slow-release coating layer is soaked in gastric juice and conveyed to intestinal tracts, uniform pores and cracks are reserved after the acidifier and the trehalose on the slow-release coating layer are exhausted, so that moisture in the intestinal tracts can conveniently enter the nucleus body, the volume of the disintegrating agent expands after water absorption, and the supporting framework is still maintained because the polyhydroxy butyrate is still used, and the disintegrating agent can only slowly extrude the acidifier in the nucleus body out of the slow-release coating layer through the pores and the cracks. In the conveying process, the polyhydroxybutyrate and polycaprolactone can also be used as carbon sources of a microorganism system in an animal organism, so that the balance of intestinal flora is promoted, and the biological immunity is improved. Even if intestinal flora is not completely digested by frames formed by polyhydroxybutyrate and polycaprolactone, the intestinal flora can be converted into feces to be discharged out of the animal body, and the feces are further degraded by in-vitro microorganisms, so that the intestinal flora has good environmental friendliness.

In conclusion, the feed additive can enable the acidulant of the slow-release coating layer to enter gastric juice to improve stomach environment, and enable the acidulant of the nucleosome to enter intestinal canal to improve intestinal canal environment, so that the feed additive has good slow-release effect in gastric juice and intestinal canal, is beneficial to improving biological immunity, is small in dosage in a feed formula, has good acidulation effect on gastric juice and intestinal canal, and can effectively improve the use convenience of the acidulant in feed.

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

By adopting the technical scheme, if the dosage of the slow-release coating layer is too large, the acidulant in the nucleus body is difficult to release effectively, and the weight ratio is suitable.

Preferably, 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.

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

By adopting the technical scheme, the acidulant of the application can be organic acid, inorganic acid or mixed acid compounded by the organic acid and the inorganic acid, wherein citric acid, fumaric acid, lactic acid, malic acid, sorbic acid, formic acid, acetic acid and propionic acid are organic acids, phosphoric acid, sulfuric acid and hydrochloric acid are inorganic acids, and the acidulant is common in animal feed, and has wide sources and excellent acidulant effect. In the present application, a further preferred acidulant 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, 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 indicate 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. According to experiments, an acidulant prepared by mixing citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid in a weight ratio of 5:5:2:1:1 is further preferable.

Preferably, the disintegrating agent is one or a mixture of more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, crosslinked polyvinylpyrrolidone and crosslinked sodium carboxymethyl cellulose.

By adopting the technical scheme, the sodium carboxymethyl starch, the low-substituted hydroxypropyl cellulose, the crosslinked polyvinylpyrrolidone and the crosslinked sodium carboxymethyl cellulose all have good water absorption, and can provide good loading effect for the acidulant.

In a second aspect, the present application provides a method for preparing a feed additive comprising an acidulant, comprising the steps of: preparation of a core material: heating polycaprolactone until the polycaprolactone is melted, adding an acidulant, stirring uniformly, adding a disintegrating agent, continuously stirring until the materials are dispersed uniformly, rapidly cooling, and grinding into powder to obtain a nuclear material;

preparation of a slow-release coating liquid: dissolving polyhydroxybutyrate in chloroform to obtain polyhydroxybutyrate-chloroform solution, dissolving polyethylene glycol, an acidulant and trehalose in ethanol to form mixed solution, and uniformly mixing the polyhydroxybutyrate-chloroform solution with the mixed solution to obtain slow-release coating solution;

coating and granulating: and (3) adding the nuclear material into the slow-release coating liquid for coating, preparing coated powder by a spray granulation method, and then carrying out irradiation treatment to obtain the feed additive.

When the slow-release coating liquid is prepared, the polyhydroxybutyrate is dissolved by chloroform, the polyethylene glycol, the acidulant and the trehalose are dissolved by ethanol, and the components are uniformly mixed by mutual dissolution of the chloroform and the ethanol to form a uniform and stable slow-release coating liquid; in order to realize coating, when preparing a core material, polycaprolactone is heated and melted firstly, and is convenient to mix in an acidulant to enable the acidulant to be adhered to a disintegrating agent, wherein the polycaprolactone acts together with the disintegrating agent, so that the acidulant in a core body can be reduced from being dissolved in ethanol of a slow-release coating liquid, and therefore, the formed feed additive has a good core-shell structure to ensure excellent slow-release effect, and meanwhile, the slow-release coating layer and the acidulant in the core body have a concentration difference, so that the acidulant in the shell body is convenient to slowly release. The spray granulation method is favorable for the rapid volatilization of chloroform and ethanol in the slow-release coating liquid in the granulation process, so that the residual quantity of chloroform and the residual quantity of ethanol in the feed additive are effectively reduced, and the safety of the feed additive is ensured.

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

By adopting the technical scheme, the homogenization and ultrasonic treatment can promote the slow-release coating liquid to be uniformly dispersed around the core material to coat the core material, thereby obtaining the feed additive with uniform coating.

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

By adopting the technical scheme, the volatile chloroform and ethanol can be timely removed by air extraction treatment, so that the polyhydroxybutyrate, polyethylene glycol, an acidulant and trehalose are stably coated outside the nuclear body to form the slow-release coating liquid.

In a third aspect, the present application provides a pet food comprising the 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 biological immunity, has small dosage in a feed formula, has good acidification effect on gastric juice and intestinal tracts, and can effectively improve the use convenience of the acidulant in feeds.

2. The special acidulant is selected and used in the application, is stable in the feed additive system, and can better realize the slow release effect.

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

Detailed Description

Raw material source

The raw materials used in the embodiments of the present application are all commercially available products. Of these, polyhydroxybutyrate, illustrated by PHB, is available from Basoff under the designation 1001MD; polyethylene glycol is exemplified by PEG-4000.

The present application is described in further detail below in connection with examples and comparative examples.

Examples

Example 1

The feed additive containing the acidulant comprises a nucleus body and a slow-release coating layer arranged on the outer side of the nucleus body, and the preparation method comprises the following steps of:

(1) preparation of core materials

Weighing 156g of polycaprolactone, placing the polycaprolactone at 70 ℃ (allowing fluctuation in the temperature range of 60-80 ℃) to be heated to be molten, adding 406g of acidulant, stirring uniformly, adding 188g of disintegrating agent, continuing stirring until the materials are dispersed uniformly, cooling at the speed of 10 ℃/s, grinding into powder, and sieving with a 100-mesh screen to obtain a core material for forming a 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 disintegrating agent can be one or a mixture of more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, crosslinked polyvinylpyrrolidone and crosslinked sodium carboxymethyl cellulose, and the sodium carboxymethyl starch is taken as an example for illustration in the embodiment;

(2) preparation of slow-release coating liquid

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

(3) coating and granulating

Adding the nuclear 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, continuously extracting gas in a coating tank during stirring for 30s each time, keeping the gas pressure in the coating tank at 0.5-0.8 atm, preparing coated powder by spray granulation after coating, and carrying out electron beam irradiation treatment on the coated powder, wherein the radiation dose is 15kGy (allowed to fluctuate within a range of 12-18 kGy), thereby preparing the feed additive.

Examples 2 to 4

Examples 2-4 the amounts of the components of the core and the slow release coating were adjusted based on the procedure of example 1, see below.

Table-amount adjustment Table (unit g) of examples 1 to 4

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 nucleus with beeswax based on the composition and method of example 1.

Comparative example 3

This comparative example replaces polyhydroxybutyrate with hydroxypropyl methylcellulose phthalate (HPMCP) based on the components and methods of example 1.

Comparative example 4

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

Comparative example 5

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

Comparative example 6

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

Performance testing

(1) Moisture resistance test

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 placed in an environment at 40℃and 75% humidity was measured, and the test results were shown in Table II below.

Table II examples 1 to 4 and comparative examples 1 to 6 were given in terms of water content (unit:%)

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

In combination with Table II, examples 1-4 are feed additives prepared correspondingly from different component materials, and tested for 28 days in an environment with a temperature of 40 ℃ and a humidity of 75%, the increased moisture content is obviously reduced compared with that of comparative document 1, so that the feed additives prepared by the method have better moisture resistance and are more beneficial to transportation and storage, and the method is beneficial to improving the use convenience of the acidulant in feeds to a certain extent. In addition, the feed additives prepared in comparative examples 2 to 4 are more likely to absorb moisture, and the feed additive prepared in comparative example 5 has better moisture resistance, probably because the feed additives prepared in comparative examples 2 to 4 are difficult to crosslink at the hinge of the slow-release coating layer and the core body, and moisture is likely to be absorbed by hydrophilic components in the slow-release coating layer to cause moisture absorption; the feed additive prepared in comparative example 5 directly causes the slow-release coating layer to be completely crosslinked, so that the structure of the slow-release coating layer is firmer, and the difficulty of moisture absorption into the slow-release coating layer and infiltration into the nucleus body is increased. The feed additive of comparative example 6, in which the disintegrant was replaced, had little effect on moisture resistance, and it was found that the slow release coating layer of the present application was sufficient to provide good coating effect on the core components.

(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, shaking, and diluting with water to 1000 mL; the artificial intestinal juice is phosphate buffer (containing pancreatin) (pH 6.8).

The feed additives prepared in examples 1 to 4 and comparative examples 1 to 6 were used as samples, and gastric juice release and intestinal juice release tests were sequentially performed on the samples with artificial gastric juice and artificial intestinal juice. The dissolution rate (%) at different times is determined by a third method of the dissolution rate and release rate determination method of 0931 in the fourth part of Chinese pharmacopoeia, and the test results are shown in the following Table III.

Table III dissolution rates (unit:%)

In combination with Table III, in the dissolution test of examples 1 to 4, the dissolution rate and dissolution time of the acidulant are increased approximately linearly, and compared with comparative example 1, the acidulant in the feed additive of the application can be released slowly and orderly, 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 more than 90% after the feed additive is treated in artificial intestinal juice for 6 hours, wherein the dissolution rate of example 3 is obviously faster than that of example 1. This is probably because when polycaprolactone in the core is replaced with other binders such as beeswax (comparative example 2) or the core and the slow-release coating layer are not subjected to radiation treatment (comparative example 4), polyhydroxybutyrate in the slow-release coating layer is not crosslinked and is easy to crack and disintegrate, so that a stable supporting frame is difficult to provide for the core, and the acidifier is released in advance; if the polyhydroxybutyrate in the slow-release coating layer is replaced by other coating materials (comparative example 3), the polyhydroxybutyrate is dissolved once entering intestinal juice, and the acidulant is released in a large amount, so that the slow-release effect is difficult to realize in the intestinal juice. The slow release coating layer of comparative example 5 contains both polyhydroxybutyrate and polycaprolactone, and after irradiation treatment, the whole coating layer can be crosslinked, so that the core-shell structure of the obtained feed additive is too stable, and the acidulant in the core is difficult to completely release.

Therefore, polyhydroxybutyrate (PHB) is used as a coating main material of the slow-release coating layer and is matched with polycaprolactone in the nucleus body, and only the junction of the slow-release coating layer and the nucleus body is crosslinked after irradiation treatment, so that the stability of a core-shell structure can be improved to a certain extent, the slow-release coating layer can have a gradual fragmentation process in intestinal juice, the slow release of an acidulant in gastric juice and intestinal juice can be realized, and the higher final dissolution rate (dissolution rate of artificial intestinal juice for 8 hours) of the acidulant is ensured.

In addition, in comparative example 6, since no disintegrant is added, the acidulant in the nucleus lacks the power of extruding outwards, the dissolution rate is greatly reduced, a large amount of acidulant is still unreleased after the artificial intestinal juice is treated for 8 hours, and the condition that the acidulant is discharged out of the body after being not utilized easily occurs, so that the bioavailability of the feed additive is lower.

Therefore, the components of the nucleus and the slow release coating layer in the feed additive are matched with each other and are combined into a whole, so that the feed additive has the advantages of excellent acidification effect, long slow release period, high bioavailability and the like, and the dosage in a feed formula can be reduced.

(3) Experimental animal effect test

The test is 2022 month 3-2022 month 4, 110 young mice with weight difference within 2g and good health state are selected and randomly divided into 11 groups, which correspond to examples 1-4, comparative examples 1-5 and blank control respectively, wherein the basic ration is commercial mouse grain, the feeding period is 20 days, the feeding conditions of each group are shown in the following table IV, the feed-meat ratio (average daily feed intake/average daily gain) of each group of mice is measured, and the measurement results are shown in the following table five.

Meter four feeding condition meter

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

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

	Average daily gain/g/d	Average daily feed intake/g/d	Feed to meat ratio
				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 the table four and the table five, the feed additives (compared with the blank control group) of the examples 1-4 can obviously improve average daily feed intake and average daily weight gain of mice, and the feed-meat ratio is obviously reduced. The lower the feed conversion ratio is, the more feed is converted into energy to be absorbed and utilized by mice, so that the feed additive can promote the appetite of animals and effectively improve the bioavailability of the feed. In comparative examples 1 to 6, although comparative example 1 had an average daily feed intake similar to that of example 1, the average daily gain thereof was lower, and thus meat was obtained with a feed ratio higher than that of the present application; the average daily feed intake and average daily weight gain of comparative examples 2-6 are lower than those of the present application, and the feed conversion ratio is also higher than that of the present application, so that the feed additive of the present application has higher promotion effect on improving the feed utilization rate.

In view of the above test results, the feed additive of example 1 has a good moisture resistance and good convenience of use, and in addition, the slow release effect in gastric juice and intestinal juice is more excellent, and the feed conversion ratio is lower, so that the present application takes example 1 as a preferred example.

Examples 5 to 9

Examples 5-9 the weight ratio of core to slow release coating was adjusted based on the method and composition of example 1, see table six below.

Table six weight ratio of core and sustained release coating 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 examples 5 to 9 were subjected to the above test for hygroscopicity, gastric fluid release and intestinal fluid release, and test for effect on experimental animals, and the results of the test were shown in tables seven to nine.

Table seven Water content (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 eight dissolution rates (unit:%)

Table nine examples 1, 5-9 mean weight gain for mice

In combination with tables seven to nine, the moisture absorption condition of the feed additive can be slowed down along with the increase of the proportion of the slow-release coating layer, and meanwhile, the dissolution efficiency of the acidulant in gastric juice and intestinal juice can be reduced to a certain extent. In the experimental animal effect test, as the duty ratio of the slow-release coating layer is increased, the average daily feed intake of animals is increased, but the average daily gain is reduced, which is probably due to the fact that more acidulant is contained in the slow-release coating layer with a large duty ratio to promote the animals to increase appetite, but the core duty ratio in the feed additive is correspondingly reduced, so that the acidulant entering the intestinal tract can be rapidly disintegrated, and the intestinal juice is difficult to be continuously and stably acidified, so that the feed meat of the animals is higher. Among the above embodiments, the overall effect of embodiment 1 is optimal, and thus it is considered as a preferred embodiment.

Examples 10 to 14

Examples 10-14 are based on the components and methods of example 1, with the proportions of acidulant being adjusted, as shown in Table ten below.

Table Ten examples 1, 10-14, formulation tables (units: parts) of acidulants

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	6	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 examples 10 to 14 were subjected to the above test of moisture absorption performance, gastric juice release and intestinal juice release, and test of experimental animal effect, wherein the effect of the catalyst adjustment on moisture absorption performance and dissolution rate was small, and the results of the test of experimental animal effect are shown in the following table eleven.

Table eleven examples 1, 10-14 average weight gain of mice

	Average daily gain/g/d	Average daily feed intake/g/d	Feed to meat ratio
				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 combination with table eleven, in the feed additive of the present application, the "acidulant" is defined as comprising the following components in parts by weight: when 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 are used, organic acid and inorganic acid are covered, the average daily gain of animals can be effectively improved in the feed additive system, and the effect of improving the acidification effect of gastric juice and intestinal tracts can be indirectly indicated to better absorb nutrition, so that the biological immunity of the animals is improved. Further preferred is an acidulant comprising 5:5:2:1:1 by weight of citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid (example 1).

Example 15

This example replaces the homogenization treatment of the coated plasmid of step (3) with sonication for 20min based on the composition and method of example 1. The performance of the prepared feed additive is similar to that of the feed additive in the embodiment 1, and the application can promote the slow-release coating liquid to be uniformly dispersed around the core material for coating by adopting homogenization and ultrasonic treatment, so that the feed additive with uniform coating is obtained.

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

The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.

Claims

1. The feed additive containing the acidulant is characterized by comprising a core body and a slow-release coating layer arranged on the outer side of the core body, wherein the weight ratio of the core body to the slow-release coating layer is (6-8): (1-3), and the core body and the slow-release coating layer are combined into a whole through irradiation treatment;

the nucleus comprises the following components in parts by weight: 50-80 parts of acidulant, 20-30 parts of polycaprolactone and 30-40 parts of 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 acidulant and 5-10 parts of trehalose;

the preparation method of the feed additive comprises the following steps:

preparation of a core material: heating polycaprolactone until the polycaprolactone is melted, adding an acidulant, wherein the acidulant is formed by mixing citric acid, fumaric acid, sorbic acid, propionic acid and hydrochloric acid according to the weight ratio of 5:5:2:1:1, adding a disintegrating agent after uniformly stirring, continuously stirring until the materials are uniformly dispersed, rapidly cooling, and grinding into powder to obtain a nuclear material; the disintegrating agent is one or more of sodium carboxymethyl starch, low-substituted hydroxypropyl cellulose, crosslinked polyvinylpyrrolidone and crosslinked sodium carboxymethyl cellulose;

preparation of a slow-release coating liquid: dissolving polyhydroxybutyrate in chloroform to obtain polyhydroxybutyrate-chloroform solution, dissolving polyethylene glycol, an acidulant and trehalose in ethanol to form mixed solution, and uniformly mixing the polyhydroxybutyrate-chloroform solution with the mixed solution to obtain slow-release coating solution; 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;

coating and granulating: and (3) adding the nuclear material into the slow-release coating liquid for coating, continuously carrying out air extraction treatment during coating, keeping the coating ambient air pressure to be 0.5-0.8 times of the standard atmospheric pressure, preparing coated powder by a spray granulation method, and then carrying out irradiation treatment to obtain the feed additive.

2. The feed additive according to claim 1, wherein: and homogenizing or ultrasonic treating the core material and the slow-release coating liquid.

3. A pet food, characterized in that: a feed additive comprising the composition of claim 1 or 2.