WO2003077674A1

WO2003077674A1 - A feed additive of nanometer size, a process preparing the same and a feed containing the feed additive of nanometer size

Info

Publication number: WO2003077674A1
Application number: PCT/CN2002/000538
Authority: WO
Inventors: Zirong Xu; Ying Ye; Meisheng Xia; Caihong Hu
Original assignee: Zhejiang University
Priority date: 2002-03-18
Filing date: 2002-08-05
Publication date: 2003-09-25
Also published as: AU2002327262A1; CN1372815A

Abstract

The present invention relates to a feed additive of nanometer size and a process for preparing the same. Said additive consists of a composition of copper modified montmorillonite and zinc modified montmorillonite in a weight proportion of 1:0.5-20. Said additive has such extreme high antibiosis and antiviral properties that it can be used to substitute for the antibiotics and growth promotion feed additives. The present invention also relates to a feed containing the feed additive of nanometer size.

Description

Nano servo feed additive, preparation method thereof, and feed containing the same TECHNICAL FIELD

The invention relates to a nano-feed additive with health-care and growth-promoting effects, a preparation method thereof, and a feed containing the additive. Background technique

Under the conditions of intensive, large-scale, automated, mechanized feeding and management of modern animal husbandry, the ecological environment of animal feeding, the threat of epidemic diseases, stress, nutritional restrictions, and other problems require one or more anti-pathogenic pathogenic microbial drugs, Intervention and application of health agents such as antiparasitic drugs. As is known to all, antibiotic growth promoters, antibacterial and antiparasitic drugs, high copper and high zinc preparations are used as feed additives to promote the growth of animals, prevent the infection of pathogenic bacteria and the occurrence of diseases, and develop the feed industry and animal husbandry. Made a great contribution. However, with the deepening of scientific understanding, people have a deeper understanding of the side effects brought by antibiotics and chemicals, such as endogenous or double infection caused by the abuse of antibiotics, the generation of drug-resistant strains, animal cell immunity, and body fluids. The decline in immune function and the residue of drugs in livestock and poultry products have made the safety of animal products increasingly prominent; for example, high copper and high zinc growth promoters have caused side effects such as animal poisoning, environmental pollution and waste of resources. For these reasons, many countries and breeders oppose the use of antibiotics and chemicals as feed additives, and even ban more and more antibiotics through legislation. Therefore, the research on non-toxic, harmless and pollution-free growth promoters and health care agents has received increasing attention.

Montmorillonite is a bioctahedral layered natural nano-sized aluminosilicate mineral. In some mining areas in China, high-purity nano-montmorillonite minerals form millions of tons of large-scale deposits. Due to its special physical and chemical properties on the surface, it has strong adsorption and ion-exchange capabilities; against various viruses (such as rotavirus, coronavirus, epidemic diarrhea virus and infectious gastroenteritis virus), pathogenic bacteria (such as E. coli , Vibrio cholerae, Campylobacter jejuni, Staphylococcus aureus) and the toxins produced (selectively fixed and inhibited) have excellent adsorption capacity; Montmorillonite can form a colloidal protective film in the digestive tract and can accelerate Repair and regeneration of damaged mucosal epithelial cells, play a role in strengthening, repairing, and protecting the mucosal barrier of the digestive tract; it can be used clinically to treat acute and chronic diarrhea, bowel stress syndrome, inflammatory bowel disease, esophagitis, gastritis, digestion Ulcers and gastrointestinal symptoms associated with non-digestive diseases. Summary of the Invention

The object of the present invention is to provide a nano feed additive with health-care and growth-promoting effects; Another object of the present invention is to provide a method for preparing the nano-feed additive.

It is still another object of the present invention to provide a feed containing the nano-feed additive.

The object of the present invention is achieved by the following concepts:

A nano-feed additive with a health-care and growth-promoting effect, characterized in that it contains a copper-modified montmorillonite in a weight ratio: a zinc-modified montmorillonite = 1: 0. 5 ~ 20 composite, said Copper-modified montmorillonite and zinc-modified montmorillonite are prepared from copper ions, zinc ions and nano-montmorillonite through ion exchange and adsorption reactions.

The nano-montmorillonite is a layered aluminosilicate, the unit cell of which is composed of two layers of silicon-oxygen tetrahedron sandwiched by a layer of aluminum-oxygen octahedron, and the two are connected by a common oxygen atom; High-purity montmorillonite with a surface area of 260-700 m ² / g, montmorillonite wafer thickness <60 11111, particle size of 0.1 ~ 10 μ π, content of 90-98%, which can be according to the purification methods in the prior art, It is obtained by treating montmorillonite mineral, montmorillonite-containing bentonite or other montmorillonite-containing mineral as raw materials. For the purification methods in the prior art, please refer to, for example, Rong Kuiyi, Long Xiaoqing, etc .: "Methods and Principles of Wet Purification and Modification of Montmorillonite", "Mineral Protection and Utilization", 1996, (3): 14- 16; Wang Zemin, Zhou Fengqi, etc .: "Purification and Application of Bentonite", "Nonmetallic Ore", 1999, 22 (3): 19-20; Wu Dongyin, Wei Min, etc., "Research on Bentonite Wet Purification", "Nonmetal "Mining", 2000, 23 (3): 23-24; Wu Dongyin, Wei Min, etc. "Purification, development and application of bentonite", "Mineral Protection and Utilization", 2000, (3): 14-16 and other methods described in literature .

The copper-modified montmorillonite is in a weight percentage, and the content of copper element in the copper-modified montmorillonite is 1.5 to 8.5%. The content of the zinc-modified montmorillonite in the zinc-modified montmorillonite is 1.5 to 5% by weight.

A feed containing 0. 1-1. 0% by weight of the aforementioned nano-additives based on the total weight of the feed.

The steps of the nano feed additive preparation method are as follows:

1) Preparation of copper-modified montmorillonite:

a) The nano-montmorillonite mineral purified according to the prior art together with an equivalent weight of the mineral of about 5% to: L5% sodium chloride, stir well with water, and make a suspension slurry with a concentration of 20% to 30%, and wash with water 4 ~ 7 times;

b) Add CuCl ₂ or Cu (N0 ₃ ) ₂ or CuS0 ₄ * 5¾0 equivalent to 5% ~ 30% of the weight of the mineral, and re-form into a slurry with a concentration of 5% ~ 15% with water, and use a dilute sodium hydroxide solution, preferably It is a sodium hydroxide solution having a concentration of 0.1- 1 moL / L to adjust the pH value of the paddle to 4. 5 ~ 6.5, washing 3 ~ 5 times with water, filtering or centrifugal dehydration;

c) The filter residue is dried and pulverized under vacuum at less than 80 Torr, preferably using a jet mill dry pulverization method, or the slurry obtained in step (b) is spray-dried to a moisture content of <10% (by weight percentage), copper element 5%。 Content of copper-modified montmorillonite is 1. 5 ~ 8. 5%.

2) Preparation of zinc-modified montmorillonite:

a) The nano-montmorillonite mineral purified according to the prior art method is equivalent to about 5% ~ 15% sodium chloride, add water and stir well to make a suspension slurry with a concentration of 20% to 30%, and wash it 4 to 7 times; b) add 5% to 40% of ZnCl ₂ or Zn (N0 ₃ ) ₂ or ZnS0 ₄ * 7H ₂ 0, reconstitute the pulp with a concentration of 5% ~ 15% with water, and use a dilute sodium hydroxide solution, preferably a concentration of 0.1 to 1-1 moL / L of sodium hydroxide solution. The pH value of the material is adjusted to 4.5 ~ 6.5, washed 4 ~ 6 times with water, filtered or centrifuged; c) the filter residue is dried and pulverized in a vacuum below 8 (TC, preferably with a jet mill dry pulverization method) 5〜10%。 Or, (b) The slurry obtained by spray drying to a water content of <10%. By weight percentage, the content of zinc element in zinc-modified montmorillonite is 1. 5 ~ 10%.

3) Compounding: The components obtained in steps (1) and (2) are mixed according to a ratio of copper-modified montmorillonite: zinc-modified montmorillonite = 1: 0. 5 ~ 20, preferably added to a screw mixer Mix well.

In one embodiment, the prepared ultra-fine powdered product can be directly added to the feed in an amount of 0.:!~1.0%.

In the present invention, antibacterial, growth-promoting copper ions and zinc ions are implanted into the montmorillonite crystal lattice through adsorption and ion exchange reactions to prepare metal ions ~ inorganic nanomaterials. On the one hand, the copper and zinc ions have a small hydration radius and high electricity price, and are inserted into the mineral lattice to increase the mineral surface potential, so that they become highly positively charged cationic nanomaterials, and improve their ability to adsorb pathogenic microorganisms; Utilizing the huge specific surface area of nanomaterials and the slow-release and controlled-release effects of minerals to increase the activity of metal ions and make their effects last longer; thereby making the modified montmorillonite have a stronger ability to adsorb pathogenic microorganisms, And through the dissolution of metal ions, it has the effect of killing various pathogenic microorganisms. Therefore, the present invention organically combines the antibacterial, growth-promoting properties of copper and zinc ions and the strong ion exchange, absorption, positioning and other properties of montmorillonite, and provides a nano-montmorillonite as a carrier and copper Copper and zinc ions with zinc ions as antibacterial and growth-promoting active ingredients ~ Montmorillonite composite nano-feed additive and preparation method thereof, and adding the additive to feed as a growth promoter and health agent to produce safe animal products .

The application of the nano-feed additive of the present invention as an animal growth promoter and health agent in the corpus includes antibacterial, antiviral, improving animal survival rate, reducing animal diarrhea, improving animal weight gain and feed conversion efficiency. The additive has strong resistance to pathogenic microorganisms, has the advantages of drug resistance, low production cost, safe use, etc., and can reduce the rate of animal diarrhea, improve the survival rate of animals, increase the weight of animals and the conversion rate of feed. The application of the nano-feed additive of the present invention can fundamentally eliminate the residues of antibiotic-type growth promoters, antibacterial and anti-parasite drugs, high copper and high zinc preparations in animal products, produce high-quality animal products, and reduce environmental pollution. Improving animal production performance and human health, greatly improving the economic benefits of the breeding industry. detailed description

The present invention is further described in conjunction with the following examples Example 1

Preparation: According to the "Methods and Principles of Wet Purification and Modification of Montmorillonite" (Rong Kui Yi et al.), Depolymerize and disperse and separate and purify the montmorillonite to obtain a montmorillonite with a purity of 96% (namely, nano-montmorillonite). ).

1) Preparation of copper-modified montmorillonite: (a) The montmorillonite mineral obtained in the preliminary step, together with sodium chloride equivalent to 5% of the mineral weight, are stirred with water and stirred to make a suspension slurry of 30% concentration. , Washed 4 times with water; (b) added CuCl ₂ equivalent to 15% of the weight of the mineral, remade into a 10% concentration ore paddle with water, adjusted the pH value with a dilute sodium hydroxide solution, and washed 3 times with water; (c) the obtained slurry Spray-dried to water content <10%. The copper-modified montmorillonite prepared according to the above steps has a copper content of 6% in the copper-modified montmorillonite.

2) Preparation of zinc-modified montmorillonite: (a) The montmorillonite mineral obtained in the preliminary step, together with sodium chloride equivalent to 5% of the weight of the mineral, was added with water and stirred to make a suspension slurry having a concentration of 30%. Wash 4 times; (b) Add 25% zinc sulfate heptahydrate (ZnS0 ₄ · 7¾0) corresponding to the weight of the mineral, and reconstitute 10% mineral violet with water. Adjust the pH value with dilute sodium hydroxide solution and wash 4 times with water. (C) The slurry obtained is spray-dried to a moisture content of <10%. The content of zinc in the zinc-modified montmorillonite obtained by the above steps is 4%.

3) Compounding: Add the components obtained in steps 1 and 2 to the screw-mixed montmorillonite: zinc-modified montmorillonite in a ratio of = 1: 20 to mix thoroughly.

In vitro studies have shown that the nano-feed additive has adsorption and killing effects on E. coli, Salmonella, Staphylococcus aureus, and rotavirus. Adding 0.1% nano-feed additives, the daily weight gain of broilers and piglets increased by 14.75% and 10.24%, the feed weight ratio was reduced by 7.45% and 8.03%, respectively; the diarrhea rate was reduced by 94 50% and 80. 73%. After acute toxicity, accumulation toxicity, mutagenicity and subchronic tests, the results show that the nano-word additive has no mutagenicity, teratogenic effect, and no accumulation toxicity, and it is safe as a livestock and poultry feed additive for a long time. Example 2

1) Preparation of copper-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 10% of the weight of the mineral, was added with water and stirred to make a suspension with a concentration of 25%. Liquid slurry, washed 5 times; (b) adding 5% of CuCl ₂ equivalent to the weight of the mineral, re-made into a 15% concentration slurry with water, adjusted the pH value with a dilute sodium hydroxide solution, washed 4 times with water, and centrifuged; (c) ) The filter residue is dried under vacuum at less than 80 Torr and pulverized by a jet mill. 9%。 Copper-modified montmorillonite prepared according to the above steps, the content of copper element in copper-modified montmorillonite is 1.9%.

2) Preparation of zinc-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 15% of the weight of the mineral, was stirred with water to make a 20% concentration. Suspension slurry, washed 7 times; (b) ZnCl ₂ equivalent to 20% of the weight of the mineral was added, and a slurry of 8% strength was reconstituted with water, the pH was adjusted with a dilute sodium hydroxide solution, washed 5 times with water, and dewatered by centrifugation; Dry under 80 ° C under vacuum and dry with a jet mill. 5%。 Zinc-modified montmorillonite prepared according to the above steps, the content of zinc element in the zinc-modified montmorillonite is 8.5%.

3) Compounding: Add the components obtained in steps 1 and 2 to the screw-mixed montmorillonite and zinc-modified montmorillonite at a ratio of = 1: 0.5 to mix thoroughly.

In vitro studies show that the nano-feed additive has adsorption and killing effects on E. coli, Salmonella, and Staphylococcus aureus. The addition of 0.4% nano-feed additives increased the survival rates of broilers, broilers and piglets by 9.14%, 5.87%, and 5.49%, and increased the daily weight gain of broilers and piglets by 9.70% and 12. 81%, reducing the weight-to-weight ratio by 10. 43% and 6. 15%, respectively; reducing the diarrhea rate by 74. 80% and 80. 81%, respectively. Example 3

1) Preparation of copper-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 12% of the weight of the mineral, was added with water and stirred to make a suspension with a concentration of 25%. Liquid slurry, washed 4 times with water; (b) adding CuS0 ₄ * 5¾0 equivalent to 8% of the weight of the mineral, re-made into a slurry with a concentration of 12% with water, adjusted the pH value with a dilute sodium hydroxide solution, and washed 3 times with water; (c) The obtained slurry was dried by spraying to a water content of <10%. 5%。 Copper-modified montmorillonite prepared according to the above steps, the content of copper element in the copper-modified montmorillonite is 1.5%.

2) Preparation of zinc-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 15% of the weight of the mineral, was added with water and stirred to make a 20% suspension. Liquid mine paddle, washed 5 times; (b) adding Zn (N0 ₃ ) ₂ equivalent to 22% of the weight of the mineral, re-made into a 10% concentration pulp with water, adjusted the pH value with a dilute sodium hydroxide solution, and washed 6 times with water; (C) The resulting slurry is spray-dried to a moisture content of <10%. The content of zinc in the zinc-modified montmorillonite obtained by the above steps is 6%.

3) Compounding: The components obtained in steps 1, 2, and 3 are added to the spiral according to the ratio of copper-modified montmorillonite: zinc-modified montmorillonite: astragalus active ingredient ~ montmorillonite = 1: 0. 5: 2 The mixer is fully mixed.

In vitro studies show that the nano-feed additive has adsorption and killing effects on E. coli, Salmonella, and infectious gastroenteritis virus. The addition of 0.6% nano-feed additives can increase the daily weight gain of piglets and growing pigs by 9.70% and 12.86%, respectively, and reduce the feed-to-weight ratio by 8.46% and 7.61%, respectively, and reduce the diarrhea rate. 105. 71% and 84. 69%. After acute toxicity, accumulation toxicity, mutagenicity and subchronic tests, the results show that the nano-word additive has no mutagenicity, teratogenic effect, and no accumulation toxicity, and it is safe as a livestock and poultry feed additive for a long time. Example 4

1) Preparation of copper-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 5% of the weight of the mineral, was stirred with water to make a 30% concentration. The suspension slurry was washed 4 times with water; (b) Cu (N0 ₃ ) ₂ equivalent to 7% of the weight of the mineral was added, and the slurry was reconstituted to 15% with water. The pH was adjusted with a dilute sodium hydroxide solution and washed 4 times with water. Filtration; (c) The filter residue is dried under vacuum at less than 8 CTC, and pulverized by a jet mill. 5%。 Copper-modified montmorillonite prepared according to the above steps, the content of copper element in the copper-modified montmorillonite is 1.5%.

2) Preparation of zinc-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1 together with 15% sodium chloride equivalent to the weight of the mineral, stir well with water to make a 20% concentration The suspension slurry was washed 7 times with water; (b) Zn (N0 ₃ ) ₂ equivalent to 5% of the weight of the mineral was added, and a 15% concentration slurry was reconstituted with water. The pH was adjusted with a dilute sodium hydroxide solution and washed 4 times with water. Filtration; (c) The filter residue is dried under vacuum at less than 80 ° C, and pulverized by a jet mill. 5%。 Zinc-modified montmorillonite prepared according to the above steps, the content of zinc element in zinc-modified montmorillonite is 1. 5%. .

3) Compounding: Add the components obtained in steps 1 and 2 to the screw-modified montmorillonite and zinc-modified montmorillonite in a ratio of = 1: 10 and mix thoroughly.

In vitro studies show that the nano-feed additive has adsorption and killing effects on E. coli and Salmonella. Adding 1% nano-feed additives, the survival rate of broilers and piglets was increased by 11.40% and 5.81%, the daily weight gain was increased by 8.54% and 9.11%, respectively, and the feed-to-weight ratio was decreased by 6.81 % And 7. 52%; reduce the diarrhea rate by 74. 56% and 94. 87%, respectively. Acute toxicity, accumulation toxicity, mutagenicity and sub-chronic tests have shown that the nano-feed additive has no mutagenic, teratogenic effects, and no accumulation toxicity, and it is safe to use as a feed additive for livestock and poultry for a long time. Example 5

1) Preparation of copper-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with 15% of sodium chloride equivalent to the weight of the mineral, was stirred with water to make a concentration of 20 % Suspension slurry, washed 7 times with water; (b) adding 30% Cu (N0 ₃ ) ₂ equivalent to the weight of the mineral, and re-made into a 5% concentration slurry with water, adjusting the pH value with a dilute sodium hydroxide solution, and washing with 5 Second, filtration; (c) The filter residue is dried under vacuum at less than 80 ° C, and is pulverized dry by a jet mill. 5%。 Copper-modified montmorillonite prepared according to the above steps, the content of copper element in the copper-modified montmorillonite is 8.5%.

2) Preparation of zinc-modified montmorillonite: (a) The montmorillonite mineral obtained according to the preparatory steps of Example 1, together with sodium chloride equivalent to 15% of the weight of the mineral, was stirred with water to make a 20% concentration. The suspension slurry was washed 7 times with water; (b) Zn (N0 ₃ ) ₂ equivalent to 40% of the weight of the mineral was added, and the ore slurry with a concentration of 5% was reconstituted with water. Dilute the sodium hydroxide solution to adjust the pH value, wash 6 times with water, and filter; (c) The filter residue is dried under vacuum at less than 80 ° C, and pulverized by a jet mill. The content of zinc element in the zinc-modified montmorillonite obtained according to the above steps is 10%.

3) Compounding: Add the components obtained in steps 1 and 2 to the screw-modified montmorillonite: zinc-modified montmorillonite in a ratio of = 1: 5 and mix thoroughly with the screw mixer.

In vitro studies show that the nano-feed additive has adsorption and killing effects on E. coli, Salmonella, Staphylococcus aureus, rotavirus, epidemic diarrhea virus, and infectious gastroenteritis virus. Adding 0.2% nano-feed additives to increase the survival rate of broilers, broilers and piglets by 8.47%, 6.92% and 2.70% respectively; increase the daily weight gain of broilers and piglets by 11. 30% and 13. 06%, reducing the weight-to-weight ratio by 5. 14% and 5. 88%, respectively; reducing the diarrhea rate by 68. 91% and 60. 66%, respectively. Acute toxicity, accumulation toxicity, mutagenicity (including Ames test, mouse bone marrow erythrocyte micronucleus test, mouse germ cell chromosome aberration test) and subchronic test showed that the nano-feed additive was not mutagenic, It has no teratogenic effects and no accumulation toxicity, and it is safe as a feed additive for livestock and poultry for a long time.

Claims

Rights request

1. A nano-feed additive, characterized in that it comprises a copper-modified montmorillonite: zinc-modified montmorillonite II 1: 0. 5 ~ 20 composite, the copper-modified montmorillonite Stone and zinc modified montmorillonite are prepared from copper ions, zinc ions and nano montmorillonite through ion exchange and adsorption reactions.

5〜8. 5% 2. The nano-feed additive according to claim 1, characterized in that the copper-modified montmorillonite is in a percentage by weight, the content of the copper element in the copper-modified montmorillonite is 1. 5 ~ 8. 5% .

The nano-feed additive according to claim 1, characterized in that the content of zinc in the zinc-modified montmorillonite is 1.5 ~: L0% by weight percentage of the zinc-modified montmorillonite.

4. A method for preparing a nano-feed additive according to claim 1, characterized in that its steps are as follows-

1) Preparation of copper-modified montmorillonite-a) Nano-montmorillonite together with sodium chloride equivalent to 5% to 15% of the weight of the mineral, stir well with water and make a suspension slurry with a concentration of 20% to 30%, and wash with water 4 ~ 7 times;

b) Add CuCl ₂ or Cu (N0 ₃ ) ₂ or CuS0 ₄ »5¾0 equivalent to 5% ~ 30% of the weight of the mineral, and reconstitute it with water at a concentration of 5% ~: 15%, with 0.1-1 moL / L sodium hydroxide solution will adjust the pH value of the paddle to 4. 5 ~ 6. 5, washing 3 ~ 5 times, filtering or centrifugal dehydration;

c) The filter residue is dried in a vacuum at less than 80 ° F, crushed, or the slurry obtained in step (b) is spray-dried to a water content of <10%.

2) Preparation of zinc-modified montmorillonite:

a) Nano-montmorillonite together with 5% ~: 15% sodium chloride equivalent to the weight of the mineral, add water and stir well to prepare a suspension slurry with a concentration of 20% ~ 30%, and wash it 4 ~ 7 times;

b) Add 5% to 40% of ZnCl ₂ or Zn (N0 ₃ ) ₂ or ZnS0 ₄ * 7¾0 equivalent to the weight of the mineral, and reconstitute it with water at a concentration of 5% to: L5%, using 0.1 to 1 moL / L sodium hydroxide solution adjusted the pH of the slurry to 4.5 ~ 6.5, washed 4 ~ 6 times with water, filtered or dehydrated by centrifugation;

c) The filter residue is dried and pulverized under vacuum at less than 80 Torr, or the slurry obtained in step (b) is spray-dried to a water content of <10%.

3) Compounding: mixing the components obtained in steps (1) and (2) according to the ratio of copper-modified montmorillonite: zinc-modified montmorillonite = 1: 0. 5 ~ 20.

The preparation method according to claim 4, characterized in that the pulverization in steps 1) c) and 2) c) is pulverized by a jet mill.

The preparation method according to claim 4, wherein the mixing in step 3) is mixing The copper-modified montmorillonite and zinc-modified montmorillonite are added to a spiral mixer for disposition and mixing.

5%。 7. The preparation method according to claim 4, characterized in that said copper-modified montmorillonite is a weight percentage, the content of copper element in copper-modified montmorillonite is 1. 5 ~ 8. 5%.

8. The preparation method according to claim 4, wherein the content of zinc in the zinc-modified montmorillonite is 1.5 to 10% by weight percentage of the zinc-modified montmorillonite.

A feed comprising the nano additive according to claim 1 in an amount of 0.1 to 1.0% by weight based on the total weight of the feed.