CN115349577A

CN115349577A - Feed additive containing organic acid and medium-chain fatty acid and application thereof

Info

Publication number: CN115349577A
Application number: CN202211006922.4A
Authority: CN
Inventors: 魏宏逵; 彭健; 王俊
Original assignee: Huazhong Agricultural University
Current assignee: Huazhong Agricultural University
Priority date: 2022-08-22
Filing date: 2022-08-22
Publication date: 2022-11-18

Abstract

The invention discloses a feed additive containing organic acid and medium-chain fatty acid and application thereof, belonging to the technical field of feed additives. The additive is composed of organic acids and medium-chain fatty acids, wherein the medium-chain fatty acids comprise one or more of caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid and lauric acid, and the organic acids comprise one or more of acetic acid, propionic acid, lactic acid, citric acid, malic acid and benzoic acid; the mass ratio of the medium-chain fatty acid to the organic acid is 1:0.5-10. According to the invention, different MCFAs and OAs are treated with different strains, medium-chain fatty acid (caprylic acid or pelargonic acid) and organic acid (citric acid) with better antibacterial activity are screened out, and then the medium-chain fatty acid and the organic acid are combined according to a proper proportion, so that the medium-chain fatty acid and the organic acid play a stronger synergistic effect, and thus, the medium-chain fatty acid and the organic acid can play a stronger antibacterial effect on the basis of reducing the dosage of the medium-chain fatty acid and the organic acid.

Description

Feed additive containing organic acid and medium-chain fatty acid and application thereof

Technical Field

The invention relates to the technical field of feed additives, in particular to a feed additive containing organic acid and medium-chain fatty acid and application thereof.

Background

The diarrhea of the weaned pigs is a typical multifactorial disease generated under the intensive pig-raising production condition and is one of the important causes of morbidity and mortality of the weaned pigs. The causes of diarrhea of weaned piglets comprise various factors such as feed factors, pathogenic microorganism infection, virus invasion, parasite invasion, adverse environment and the like, and flora disturbance is the main cause of the diarrhea of the piglets. Intestinal flora disorders are mainly manifested by an increase in pathogenic bacteria such as escherichia coli (e.coli), salmonella (Salmonella), shigella (s.flexneri), and a decrease in probiotics such as lactic acid bacteria (Lactobacillus). On the one hand, pathogenic bacteria are increased, and toxin secretion stimulates the phosphorylation of intestinal water-salt metabolic pathways such as CFTR, so that water and electrolyte are greatly secreted into the intestinal cavity, and finally piglet diarrhea is caused. On the other hand, the study of Qiao et al (2013) reports that the number of Escherichia coli in the intestinal tract is positively correlated with the content of Reactive Oxygen Species (ROS), and the content of lactic acid bacteria in the intestinal tract is negatively correlated with the content of Reactive Oxygen Species (ROS). When piglets are weaned, intestinal flora is disordered, so that the number of escherichia coli in the intestinal tract is increased, the content of lactic acid bacteria is reduced, and the content of ROS in the intestinal tract is increased. ROS can not only directly damage the barrier function of the intestinal tract, but also indirectly damage the barrier function of the intestinal tract by stimulating the expression of inflammatory factors of the intestinal tract to cause excessive inflammatory reaction. Finally increasing the death rate of the piglets and reducing the growth performance of the piglets. To prevent diarrhea in piglets, it has been common to supplement animal feed with low doses of medicinal antimicrobial substances (e.g. antibiotics) or therapeutic doses of antibiotics over the last decades (Prescott, 1997). However, with the use of antibiotics in large quantities and in non-standard conditions, negative effects such as the generation of drug-resistant strains and the antibiotic residues in food are gradually shown, which destroy the ecological balance of the normal flora of the organism, cause the immunity of livestock to be reduced, and cause serious problems of biological safety and food safety of livestock. These effects may lead to the loss of action of the final means of treating bacterial diseases (antibiotics), which requires either an increase in their dosage or the development of new, stronger antibiotics. Thus, the european union has completely banned the use of antibiotics as antimicrobial growth promoters in 2006, and these facts indicate the need to develop antimicrobial agents with antimicrobial properties as antibiotic substitutes.

Medium Chain Fatty Acids (MCFAs) can destroy the cell wall and cell membrane of pathogenic bacteria, cause the release of cell contents, and can be dissociated into H in cytoplasm ⁺ And anions that lower the intracytoplasmic pH, thereby inactivating intracytoplasmic enzymes, resulting in the death of pathogenic bacteria. Organic Acids (OAs) are capable of passing through the cell membrane and dissociating in the cytoplasm to lower intracellular pH, thereby inactivating intracellular enzymes and causing the death of pathogenic bacteria. However, because MCFAs has an irritating odor, they affect the taste when added in a large amount in the feed, and they do not exert a good bactericidal action when added in a small amount, and OAs inhibit the secretion of gastric acid when added in a large amount in the feed, thereby limiting their use as bactericides. The plant essential oil contains natural substances for sterilization, bacteriostasis and mildew prevention, can improve the immunity and disease resistance of cultured animals, and has special aromatic smell and obvious food calling effect, so that the plant essential oil is mostly compounded with MCFAs and/or Oas to be used as an antibiotic substitute in the prior research. However, plant essential oils are volatile, easily oxidized and allergenic, and when applied to antimicrobial agents, not only are costs increased, but there is also a risk of sensitization.

Based on the technical problems, the invention aims to provide a medium-chain fatty acid and organic acid combination with a specific range and higher antibacterial activity, so that the combination can exert stronger antibacterial effect while reducing the dosage.

Disclosure of Invention

The invention aims to provide a feed additive containing organic acid and medium-chain fatty acid and application thereof, aiming at solving the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a feed additive containing organic acid and medium-chain fatty acid, wherein the mass ratio of the medium-chain fatty acid to the organic acid is 1:0.5-10;

the medium chain fatty acids include one or more of caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid and lauric acid, and the organic acids include one or more of acetic acid, propionic acid, lactic acid, citric acid, malic acid and benzoic acid.

Further, the medium-chain fatty acid is caprylic acid or pelargonic acid, and the organic acid is citric acid.

Further, the mass ratio of the medium-chain fatty acid to the organic acid is 4:5.

the invention also provides an application of the feed additive, which is applied to any one of the following applications:

(1) Use in promoting animal production;

(2) The application in preparing the medicine for preventing and treating the intestinal pathogenic bacteria infection diseases;

(3) The application in regulating and controlling the microbial ecosystem of the gastrointestinal tract.

Further, the feed additive exerts effects of promoting animal production, preventing and treating infectious diseases or regulating and controlling gastrointestinal microbial ecosystem by inhibiting and killing pathogenic bacteria.

Further, the pathogenic bacteria include enterotoxigenic escherichia coli, shigella, salmonella, and clostridium perfringens.

Further, the promotion of animal production includes increasing animal body weight, and decreasing feed-meat ratio and diarrhea rate.

The invention also provides a feed for promoting animal production, which is characterized in that the feed is obtained by adding the feed additive into basic ration by 0.01-0.1% by weight.

The invention discloses the following technical effects:

according to the invention, different MCFAs and OAs are treated with different strains, medium-chain fatty acid (caprylic acid or pelargonic acid) and organic acid (citric acid) with better antibacterial activity are screened out, and then the medium-chain fatty acid and the organic acid are combined according to a proper proportion, so that the medium-chain fatty acid and the organic acid play a stronger synergistic effect, and thus, the medium-chain fatty acid and the organic acid can play a stronger antibacterial effect on the basis of reducing the dosage of the medium-chain fatty acid and the organic acid.

According to the invention, the feed additive containing the medium-chain fatty acid and the organic acid is fed to the mice infected with pathogenic bacteria, and the result shows that the feed additive has the functions of promoting the growth of the infected mice and relieving the probability of diarrhea after infection; the additive is used for feeding weaned piglets, can obviously improve the growth performance of the piglets, and reduce the diarrhea rate and the diarrhea index, and is beneficial to preventing the weaned diarrhea of the piglets. Therefore, the fatty acid and organic acid combined feed additive with compatibility and antibacterial activity in a specific range can play a strong role in synergism and antibiosis, reduce animal diarrhea, and effectively prevent and treat diseases caused by animal infection pathogenic bacteria, and meanwhile, the raw materials used in the invention are safe, nontoxic, low in price, and low in use cost, and have a remarkable bactericidal effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of the experimental treatment of example 4;

FIG. 2 is a statistical chart of diarrhea rate and diarrhea index of each group of piglets in example 4; left panel: the rate of diarrhea; right drawing: the index of diarrhea.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. It is intended that the specification and examples be considered as exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including but not limited to.

Example 1 treatment of different strains with different MCFAs and OAs

Experiments were performed with enterotoxigenic escherichia coli, shigella flexneri, salmonella typhimurium and clostridium perfringens, and MCFAs and OAs antibacterial activity was determined using caproic acid (C6), heptanoic acid (C7), caprylic acid (C8), nonanoic acid (C9), capric acid (C10), undecanoic acid (C11), lauric acid (C12), acetic acid, propionic acid, lactic acid, citric acid, malic acid, benzoic acid alone.

1. Test materials

1.1 test bacteria

Enterotoxigenic Escherichia coli (C83715), shigella flexneri (ATCC 12022), salmonella typhimurium (ATCC 14028), clostridium perfringens (CMCC 64701).

1.2 test reagents

Caproic acid (C6), heptanoic acid (C7), caprylic acid (C8), nonanoic acid (C9), capric acid (C10), undecanoic acid (C11), lauric acid (C12), acetic acid, propionic acid, lactic acid, citric acid, malic acid, benzoic acid, of analytical grade, available from sigma; 98% ethanol was purchased from chemical reagents of national drug group, ltd; TSB (Tryptic Soy Broth) medium powder and agarose (Agar) were purchased from OXOID; the water used in the test was double distilled water.

1.3 instruments

HZQ-F160 shaking incubator, HSP-250 biochemical incubator and clean bench were purchased from Beijing Dong Union Harr apparatus manufacturing Co., ltd. The Infinite M200 PRO visible light photometer is available from Nature technologies, inc.

1.4 reagent preparation

Caproic acid (C6), heptanoic acid (C7), octanoic acid (C8), nonanoic acid (C9), decanoic acid (C10), undecanoic acid (C11), lauric acid (C12) were dissolved in 98% ethanol at a concentration of 1M, sterilized by filtration, and stored at-20 ℃. Dissolving acetic acid, propionic acid, lactic acid, citric acid, malic acid, and benzoic acid in sterile double distilled water at concentration of 1M, filtering, sterilizing, and storing at-20 deg.C. TSB liquid medium (1L): 30g of TSB medium powder is weighed and added with 1L of double distilled water to sterilize for 30min at 121 ℃. TSB solid medium (1L): 30g of TSB medium powder and 15g of agarose are weighed, 1L of double distilled water is added, the mixture is sterilized at 121 ℃ for 30min, and the mixture is poured into a flat plate for later use.

2. Experimental design and results

2.1 MIC and MBC of MCFAs and OAs against pathogenic bacteria

Hexanoic acid (C6), heptanoic acid (C7), octanoic acid (C8), nonanoic acid (C9), single agent treatment concentration of 10,9,8,7,6,5,4,3,2,1mM; capric acid (C10), undecanoic acid (C11), lauric acid (C12) single agent treatment concentrations of 20, 15, 10,5,2.5,1.25mM; the single-agent treatment concentration of acetic acid, propionic acid, lactic acid, citric acid, malic acid and benzoic acid is 100, 50, 25 and 12.5mM. Additional blanks were set, with 4 replicates per treatment.

(1) Adding 5ml of 1 × 10 glass tube ⁶ CFU/ml TSB medium for each test strain.

(2) MCFAs and OAs were added to each tube to the final concentration as designed.

(3) And the TSB culture medium and the test bacteria are used as positive controls, the TSB culture medium and the 2% ethanol and the test bacteria are used as controls, and the TSB culture medium is used as a negative control.

(4) After incubation at 37 ℃ for 24h at 200rpm, 200ul of each concentration was pipetted into a 96-well plate and the Optical Density (OD) was read at 620 nm.

(5) Calculating the inhibition ratio f _a ，f _a ＝[(a-b)-(d-c)](a-b), wherein a is TSB culture medium + test bacteria absorbance value, b is TSB culture medium absorbance value, c is MCFAs or OAs + TSB absorbance value, and d is MCFAs or OAs + TSB + test bacteria absorbance value.

(6)f _a The MIC value is determined by the concentration of MCFAs or OAs corresponding to more than or equal to 95 percent.

(7) The cultured bacterial liquid is coated on a TSA plate, and after the bacterial liquid is cultured in a constant-temperature incubator at 37 ℃ for 24 hours, the concentration corresponding to the bacterial colony which does not grow is determined as MBC.

The Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) for different MCFAs and OAs against different pathogenic bacteria are given in Table 1,2,3,4.

TABLE 1 MIC of different MCFAs against different pathogenic bacteria

TABLE 2 MBC of different MCFAs against different pathogenic bacteria

TABLE 3 MIC of different OAs against different pathogenic bacteria

TABLE 4 MBC of different OAs against different pathogenic bacteria

As can be seen from Table 1,2, caproic acid (C6), enanthic acid (C7), caprylic acid (C8) and pelargonic acid (C9) have good antibacterial effects on gram-negative bacteria enterotoxigenic Escherichia coli, shigella flexneri and Salmonella typhimurium, but have no significant antibacterial effects on gram-positive bacteria Clostridium perfringens. Capric acid (C10), undecanoic acid (C11) and lauric acid (C12) have good antibacterial effect on gram-positive bacteria clostridium perfringens, but have no remarkable antibacterial effect on gram-negative bacteria enterotoxigenic escherichia coli, shigella flexneri and salmonella typhimurium. In general, medium chain fatty acids have greater antibacterial activity against caprylic and pelargonic acids.

As shown in Table 3,4, acetic acid, propionic acid, lactic acid, citric acid, malic acid and benzoic acid have antibacterial effects on gram-negative bacteria enterotoxigenic Escherichia coli, shigella flexneri, salmonella typhimurium and gram-positive bacteria Clostridium perfringens, wherein the citric acid and the benzoic acid have the strongest antibacterial activity.

Example 2 octanoic acid (C8) and citric acid complexes treatment of different strains

The test was performed with enterotoxigenic escherichia coli, shigella flexneri and salmonella typhimurium. The optimum ratio of caprylic acid (C8) to citric acid was determined using the weekly-tex index method.

1. Test materials

1.1 test bacteria

Enterotoxigenic Escherichia coli (C83715), shigella flexneri (ATCC 12022), salmonella typhimurium (ATCC 14028).

1.2 test reagents

Caprylic acid (C8), citric acid, analytical grade, from sigma; 98% ethanol was purchased from chemical reagents of national drug group, ltd; TSB (Tryptic Soy Broth) media powders were purchased from OXOID, inc.; the water used in the test was double distilled water.

1.3 instruments

The same as in example 1.

1.4 reagent preparation

Octanoic acid (C8), citric acid was formulated as in example 1.

2. Experimental design and results

Octanoic acid at a concentration of 7,3.5,1.75,0.875,0.4375,0.2187mM was checkerboard designed with citric acid at a concentration of 12.5,6.25,3.125,1.56,0.78, 0.39mM. Additional blanks were set, and each treatment was repeated 4 times.

(2) Caprylic acid or citric acid or a bactericidal composition was added to each tube to a final concentration designed.

(5) Calculating the inhibition ratio f _a ，f _a ＝[(a-b)-(d-c)]And (a-b), wherein a is the light absorption value of the TSB culture medium and the test bacteria, b is the light absorption value of the TSB culture medium, c is the light absorption value of the caprylic acid and the TSB, and d is the light absorption value of the caprylic acid and the TSB plus the test bacteria.

(6)f _a Concentrations of caprylic acid or citric acid corresponding to > 95% were determined as MIC values.

According to the concentration logarithm value and the inhibition rate of each substance, a regression curve is made, the MIC of each substance is calculated, whether the synergistic antibacterial effect exists is judged according to a Chou-Talalay index method, and a Combination Index (CI) after two single agents are mixed is calculated (namely CI >1 is antagonistic action, CI =1 is additive action, and CI <1 is synergistic action). The test results are shown in tables 5-7 below. The calculation results have been converted to mass concentrations.

TABLE 5 measurement of the Combined antibacterial Effect of caprylic acid and citric acid on Escherichia coli

TABLE 6 measurement of the Combined antibacterial Effect of caprylic acid and citric acid on Shigella

TABLE 7 measurement of the Combined antibacterial Effect of caprylic acid and citric acid on Salmonella

As seen from the test results of tables 5-7: the combination of caprylic acid and citric acid has obvious synergistic effect on escherichia coli (e.coli), salmonella (Salmonella), shigella (s.flexneri). For e.coli (e.coli), synergy was most evident when the mass ratio of caprylic acid to citric acid was 4. For shigella (s. Flexneri), synergy is most significant when the mass ratio of caprylic acid to citric acid is 1. For Salmonella (Salmonella), when the mass ratio of caprylic acid to citric acid is 4: and 5, the synergistic effect is most obvious. Preferably, the mass ratio of the caprylic acid to the citric acid is 4:5.

example 3 pelargonic acid (C9) and citric acid Complex treatment of different strains

The test was performed with enterotoxigenic escherichia coli, shigella flexneri and salmonella typhimurium. The optimum ratio of pelargonic (C9) to citric acid was determined using the week-to-tex index method.

1. Test materials

1.1 test bacteria

The same as in example 2.

1.2 test reagents

Pelargonic acid (C9), citric acid, analytical grade, from sigma; 98% ethanol was purchased from chemical reagents of national drug group, ltd; TSB (Tryptic Soy Broth) medium powder was purchased from OXOID; the water used in the test was double distilled water.

1.3 Instrument

The same as in example 1.

1.4 reagent preparation

Pelargonic acid (C9), citric acid was prepared as in example 1.

2. Experimental design and results

The chessboard design was performed with nonanoic acid at a concentration of 7,3.5,1.75,0.875,0.4375,0.2187mM and citric acid at a concentration of 12.5,6.25,3.125,1.56,0.78, 0.39mM. Additional blanks were set, with 4 replicates per treatment.

(1) Adding 5ml of a solution containing 1X 10 of sodium hydroxide into glass test tubes respectively ⁶ CFU/ml TSB medium for each test strain.

(2) Pelargonic or citric acids or bactericidal compositions were added to each tube to the final concentration designed.

(3) And the TSB culture medium + the test bacteria is used as a positive control, the TSB culture medium +2% ethanol + the test bacteria is used as a control, and the TSB culture medium is used as a negative control.

(5) Calculating the inhibition rate f _a ，f _a ＝[(a-b)-(d-c)]And (a-b), wherein a is the light absorption value of the TSB culture medium + the test bacteria, b is the light absorption value of the TSB culture medium, c is the light absorption value of pelargonic acid + TSB, and d is the light absorption value of pelargonic acid + TSB + the test bacteria.

(6)f _a The MIC value is determined by the concentration of pelargonic acid or citric acid which is more than or equal to 95 percent.

According to the concentration logarithm value and the inhibition rate of each substance, a regression curve is made, the MIC of each substance is calculated, whether the synergistic antibacterial effect exists is judged according to a Chou-Talalay index method, and a Combination Index (CI) after two single agents are mixed is calculated (namely CI >1 is antagonistic action, CI =1 is additive action, and CI <1 is synergistic action). The test results are shown in tables 8-10 below. The calculation results have been converted to mass concentrations.

TABLE 8 measurement of the Combined antibacterial Effect of pelargonic acid and citric acid on Escherichia coli

TABLE 9 Combined antibacterial Effect determination of pelargonic acid and citric acid on Shigella flexneri

TABLE 10 measurement of the Combined antibacterial Effect of nonanoic acid and citric acid on Salmonella typhimurium

As seen from the test results of tables 8-10: the combination of pelargonic acid and citric acid has obvious synergistic effect on escherichia coli (e.coli), salmonella (Salmonella) and shigella (s.flexneri). Coli (e.coli), when the mass ratio of nonanoic acid to citric acid is 1: when 10, the synergy is most obvious. For Salmonella (Salmonella), when the mass ratio of pelargonic acid to citric acid is 4: and when 5, the synergistic effect is most obvious. For shigella (s.flexneri), when the mass ratio of pelargonic acid to citric acid is 4: and 5, the synergistic effect is most obvious. Preferably, the mass ratio of the nonanoic acid to the citric acid is 4:5.

example 4

The feed additive containing the MCFAs and OAs compound is prepared by mixing the following raw materials: 44 parts of caprylic acid and 56 parts of citric acid. Adding into animal daily feed at a weight ratio of 0.01-0.1%. The other one is prepared by mixing the following raw materials: 44 parts of pelargonic acid and 56 parts of citric acid. Adding into animal daily feed at a weight ratio of 0.01-0.1%.

1. Test animal

ICR mice (about 3 weeks old) weighing about 10g were selected for 30 mice, randomly divided into 3 groups of 10 mice each, and fed in a single cage. The room temperature was at 21-22 deg.C for 12h light/dark cycle. The specific grouping is as in table 1.

TABLE 11 mouse challenge experiment groups

Serial number	Grouping	Number of
			1 (A group)	Basic ration and offensive toxin	10
2 (B group)	Basic ration + C9+ citric acid + counteracting toxic substance	10
			3 (C group)	Basal diet + C8+ citric acid + counteracting toxic substances	10

2. The experimental treatment flow is shown in FIG. 1.

3. Toxic materials removing process

3.1 feeding different daily rations on the 1 st day of the experiment for 7 days;

3.2 on the 7 th day of feeding (48 hours before using ETEC to orally challenge), changing the drinking water of the mice into the drinking water containing 5g/L streptomycin and 6.7 percent of fructose so as to eliminate the normal flora of the intestinal tracts of the mice;

3.3 preparation of bacteria: picking K88ac single colony in a fresh LB culture medium, and shaking the culture at 37 DEG CThe culture was carried out overnight. Inoculating 1/100 of fresh LB culture medium on the next day of virus challenge, culturing for 3.5 hr, centrifuging to obtain thallus precipitate, and re-suspending and concentrating with sterile normal saline to about 5 × 10 ⁹ CFU/mL for standby;

3.4 changing the drinking water into sterile water without streptomycin and fructose 12 hours before the toxin is attacked;

3.5 Per mouse 8 per day by oral gavage method gavage 0.2mL 5X 10 ⁹ CFU/mL K88ac fresh bacterial liquid, and normally drinking sterile water; continuously counteracting toxic substance for 7 days.

3.6 after the challenge, the mice were observed for 14 days to see the recovery condition.

4. Test indexes

4.1 growth Performance

The mice were weighed using an electronic balance on the first day of the experiment, 8 am at 00, and then daily at 8 am. Calculating the weight and daily gain of the mice.

4.2 mortality

Mice were observed daily to see if any mice died and the mortality of each group of mice was calculated.

4.3 diarrhea rate

Mice were observed for fecal material and for diarrhea. The diarrhea judgment standard is as follows: and (3) putting the filter paper under a mouse cage, observing whether the feces and the water are separated on the filter paper or not, and judging that the diarrhea exists if the feces and the water are separated. And recording the diarrhea number of the mice and calculating the diarrhea rate.

4.4 fecal moisture

Mouse feces were collected every 3 days for determination of water content of the mouse feces.

Collection time gradient: collected once a day before challenge and once every three days thereafter.

The collection time per day: collected every half hour from 8 am to 8 pm.

Measurement method: measuring the wet weight of the mouse feces immediately after collection, and then putting the feces into a 65 ℃ oven for drying for 12 hours to obtain

Dry weight. And calculating the water content of the excrement.

5. Test results

5.1 Effect of the addition of the additive of the present invention on the feed intake and body weight of mice

TABLE 12 ICR mouse growth Performance indices

Values are expressed as mean ± SEM. Different letters indicate significant differences (P < 0.05).

5.2 Effect of the addition of the additives of the present invention on the diarrhea Rate in mice

TABLE 13 ICR mice post challenge K88ac diarrhea Rate (%)

Note: and NS: diarrhea did not occur.

5.3 Effect of the addition of the additive of the invention on the moisture content of mouse feces

TABLE 14 moisture (%) change in feces after challenge of ICR mice with K88ac challenge

The combination of tables 12-14 shows that the addition of the feed additive of the invention in the feed has the effects of reducing the feed conversion ratio and diarrhea rate, reducing the water content of excrement after escherichia coli infection and promoting the growth of animals.

Example 5

A feed additive containing MCFAs and OAs complex. The health-care food is prepared by mixing the following raw materials: 44 parts of caprylic acid and 56 parts of citric acid. Adding into animal daily feed at a weight ratio of 0.01-0.1%. The other is formed by mixing the following raw materials: pelargonic acid 44 weight portions and citric acid 56 weight portions. Adding into animal daily feed at a weight ratio of 0.01-0.2%.

1. Test animals and groups

The test is carried out in a breeding field in the ovarian area of the Guigang in Guangxi in 2018, 5-2018, 6, and the three-way hybrid Du multiplied by long multiplied by large weaned piglet 400 with 21 +/-2 d and similar body weight (6.82 +/-1.00 Kg) is randomly divided into 4 groups according to the principle that the body weight and the sex are relatively consistent, the high zinc group and the low zinc group are repeated for 4 times, each group is repeated for 1 column, each column is 25 heads, and the male and female halves; the combination 1 and the combination 2 are combined into 5 repeats, wherein each repeat has 1 column, 20 heads in each column and halves of a male parent and a female parent; the test adopts single-factor test design, and the specific daily ration treatment is shown in table 15. Control group 1 was supplemented with 2250mg/kg zinc from ZnO, provided in basal diet; control group 2 added 1500mg/kg zinc in the basal diet, provided by basic zinc chloride; combination 1 group added 1500mg/kg zinc (provided by zinc chloride hydroxide) and 6000mg/kg coated octanoic acid and citric acid to the base ration and combination 2 group added 1500mg/kg zinc (provided by zinc chloride hydroxide) and 7000mg/kg coated octanoic acid and citric acid to the base ration. The test period was 2 weeks after weaning.

Table 15 test ration treatment

2. Feeding management and data recording

The breeding test is carried out in a semi-closed nursing house, the ground of the breeding fence is a cement ground, and ventilation is good. Feeding a small number of times every day, recording the feeding amount of the feed according to columns, freely drinking water, recording the residual amount of the feed in a trough at a ratio of 17. Ventilation and heat preservation measures are made, and other feeding management and immunization regulations are uniformly executed according to the regulations of the pig farm. Feeding the piglets with the feed 1-14 days after weaning. The sick pigs are found in time and treated and recorded in the feeding process, and the patients with severe symptoms are eliminated in time and the information of the ear numbers, the weight and the like of the patients is recorded. The piglets were weighed head by head at 0d, 7d and 14d post weaning. The dung discharge condition of the piglets is observed every day, the anus of the piglets is checked one by one, whether the dung is polluted or red and swollen is observed and recorded, the dung is scored according to the scoring standard of Kelly et al (1990), and the diarrhea rate and the diarrhea index of each group of piglets are calculated. The diarrhea rate reflects the incidence of the disease, and the diarrhea index reflects the severity of the diarrhea.

Diarrhea rate (%) = total diarrhea number of heads/total number of piglets tested × 100

Diarrhea index = ∑ (stool score)/total number of piglets tested

3. Test results

3.1 Effect on growth Performance of piglets

TABLE 16 piglet growth Performance

Note: the difference is very significant if the letters are not the same, P < 0.05 indicates that the difference is significant, P < 0.01 indicates that the difference is very significant, and 0.05 < P < 0.1 indicates that the trend of significant difference exists.

3.2 Effect on diarrhea rate and diarrhea index is shown in FIG. 2.

It can be seen from table 16 and fig. 2 that the addition of the feed additive of the present invention to the feed can improve the growth performance of piglets, and reduce the diarrhea rate and diarrhea index, which is beneficial to preventing weaned diarrhea of piglets.

The above-described embodiments are only intended to illustrate the preferred embodiments of the present invention, and not to limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A feed additive containing organic acid and medium-chain fatty acid is characterized in that the mass ratio of the medium-chain fatty acid to the organic acid is 1:0.5-10;

the medium-chain fatty acid comprises one or more of caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid and lauric acid, and the organic acid comprises one or more of acetic acid, propionic acid, lactic acid, citric acid, malic acid and benzoic acid.

2. The feed additive of claim 1 wherein the medium chain fatty acid is caprylic or pelargonic acid and the organic acid is citric acid.

3. The feed additive according to claim 1, wherein the mass ratio of the medium-chain fatty acid to the organic acid is 4:5.

4. use of a feed additive according to any one of claims 1-3 in any one of the following applications:

(1) Use in promoting animal production;

5. The use as claimed in claim 4, wherein the feed additive is effective in promoting animal production, preventing and treating infectious diseases or regulating gastrointestinal microbial ecosystem by inhibiting and killing pathogenic bacteria.

6. The use according to claim 5, wherein the pathogenic bacteria comprise enterotoxigenic Escherichia coli, shigella, salmonella, and Clostridium perfringens.

7. The use of claim 5, wherein promoting animal production comprises increasing animal body weight, and decreasing feed-meat ratio and diarrhea rate.

8. A feed for promoting animal production, which is obtained by adding the feed additive according to any one of claims 1 to 3 to a basal ration in an amount of 0.01 to 0.1% by weight.