CN114651899A

CN114651899A - Low-nitrogen-phosphorus-emission environment-friendly artificial compound feed and preparation method thereof

Info

Publication number: CN114651899A
Application number: CN202210270936.0A
Authority: CN
Inventors: 周建成; 杨传哲; 潘望城; 徐磊; 成琳; 朱传忠; 宿敬志
Original assignee: Wuhan Da Bei Nong Aquatic Product Technology Co ltd; Fujian Dabei Nonghuayou Aquatic Technology Group Co ltd
Current assignee: Wuhan Da Bei Nong Aquatic Product Technology Co ltd; Fujian Dabei Nonghuayou Aquatic Technology Group Co ltd
Priority date: 2022-03-18
Filing date: 2022-03-18
Publication date: 2022-06-24

Abstract

The application discloses the field of aquatic feeds, and particularly discloses an environment-friendly artificial mixed feed with low nitrogen and phosphorus emission and a preparation method thereof, wherein the artificial mixed feed is prepared from main materials and water, and the main materials comprise the following raw materials: soybean meal, rapeseed meal, low-gluten flour, rice bran, soybean oil, sodium chloride, monocalcium phosphate, nutritional additives, phytase and leveling materials; and the crude protein content of the main material is as follows; the phytase activity was 2400-2600U/kg. The preparation method comprises the following steps: weighing main material raw materials according to a ratio, blending and crushing other components except phytase in the main material to obtain a medium product; adding water into the intermediate product, then carrying out expansion to obtain an expanded material, spraying the phytase aqueous solution obtained by diluting with water on the surface of the expanded material, drying and screening to obtain the finished feed with the water content of 10-11.5%. The low-nitrogen-and-phosphorus-emission environment-friendly artificial mixed feed has the advantages of high feed utilization efficiency and low nitrogen and phosphorus emission.

Description

Low-nitrogen-phosphorus-emission environment-friendly artificial mixed feed and preparation method thereof

Technical Field

The application relates to the field of aquatic feeds, in particular to an environment-friendly artificial mixed feed with low nitrogen and phosphorus emission and a preparation method thereof.

Background

In many areas of China, aquaculture is mostly in a mixed culture mode mainly based on grass carps, the grass carps are used as herbivorous varieties, a large amount of plant protein raw materials such as soybean meal, rapeseed meal, cottonseed meal, sunflower meal and rice bran are used in a formula of an artificial compound feed commonly adopted at present, and nitrogen and phosphorus which are not utilized in the artificial compound feed are directly discharged to a water body in the form of excrement along with the increase of culture density and feeding amount, so that water eutrophication and blue-green algae outbreak are caused, and water body pollution is aggravated.

Therefore, the inventor considers that the environment-friendly artificial compound feed capable of effectively improving the utilization efficiency of the feed and reducing the emission of nitrogen and phosphorus is in urgent need.

Disclosure of Invention

In order to improve the utilization efficiency of the artificial mixed feed and reduce the emission of nitrogen and phosphorus, the application provides the low-nitrogen-and-phosphorus-emission environment-friendly artificial mixed feed and the preparation method thereof.

The first aspect, the application provides a low nitrogen phosphorus discharges environment-friendly artificial mixed feed adopts following technical scheme:

an environment-friendly artificial mixed feed with low nitrogen and phosphorus emission is prepared from main materials and water, wherein the main materials are prepared from the following raw materials in percentage by weight: 28-30% of soybean meal, 9.8-34.8% of rapeseed meal, 15-36.2% of low-gluten flour, 13-14% of rice bran, 1.5-1.67% of soybean oil, 0.45-0.55% of sodium chloride, 0.5-3% of monocalcium phosphate, 0.58-0.82% of nutritional additives, 0.03-0.05% of phytase and the balance of leveling materials; and the crude protein content of the main material is 24-30.2%;

the phytase activity is 2400-2600U/kg.

The water content in the low-nitrogen-phosphorus-emission environment-friendly artificial compound feed is preferably 10-11.5%.

By adopting the technical scheme, because the soybean meal, the rapeseed meal, the low-gluten flour, the rice bran and the monocalcium phosphate are used as main components of the main materials, the feed provides rich protein and inorganic phosphorus for the feed, and the fed fish can conveniently obtain amino acid and inorganic phosphorus; in addition, the nutritional additive can be used for increasing the weight of the fish rapidly, so that the feed effect is further improved.

In particular, the added phytase belongs to phosphoric acid monoester hydrolase, can effectively act on phytic acid (also called phytic acid) contained in a vegetable protein raw material, degrades the phytic acid into inositol and inorganic phosphorus, and can release phosphorus chelated by the phytic acid and potential protein in the vegetable protein raw material at the same time, so that the utilization rate of animals to mineral substances can be improved, the activity of digestive enzymes in vivo can be enhanced, the adding amount of protein and monocalcium phosphate in the feed can be reduced on the premise of keeping or even improving the feed effect, and the effects of reducing nitrogen and phosphorus emission, reducing water body environmental pollution, reducing the feed coefficient and improving the feed utilization efficiency can be achieved.

Preferably, the leveling material is bentonite or gunite corn bran.

By adopting the technical scheme, because the bentonite does not contain protein and has certain adsorption performance, and the gunite corn husks contain protein but have lower phosphorus content, the gunite corn husks can be used as a high-quality leveling material of the environment-friendly artificial mixed feed with low nitrogen and phosphorus emission.

Preferably, the nutritional additives include choline chloride, vitamin premix, and trace element premix.

By adopting the technical scheme, the choline chloride, the vitamin premix and the trace element premix all have the effect of quickly increasing weight as feed additives, and particularly, the choline chloride has a good effect of increasing the weight of fishes.

Preferably, the nutritional additive comprises the following raw materials in percentage by weight based on the total weight of the main materials: 0.18 to 0.22 percent of choline chloride, 0.15 to 0.25 percent of vitamin premix and 0.25 to 0.35 percent of trace element premix.

By adopting the technical scheme, the choline chloride, the vitamin premix and the trace element premix are mixed according to a specific example, a certain synergistic effect can be generated, the weight increasing effect can be exerted to the greatest extent, and the utilization efficiency of the feed is further improved.

Preferably, the main material is prepared from the following raw materials in percentage by weight: 30% of soybean meal, 26.5% of rapeseed meal, 22.16% of low-gluten flour, 13.5% of rice bran, 1.55% of soybean oil, 0.5% of sodium chloride, 0.2% of choline chloride, 0.04% of phytase, 2% of monocalcium phosphate, 0.2% of vitamin premix, 0.3% of trace element premix and 3.05% of bentonite.

By adopting the technical scheme, through selection and adjustment of the mixture ratio of the raw materials, the utilization rate of the protein of the feed prepared from the obtained main material is high, the addition of the protein in the feed is reduced, and the raw material cost and the nitrogen emission of the feed are reduced.

Preferably, the main material is prepared from the following raw materials in percentage by weight: 30% of soybean meal, 33.3% of rapeseed meal, 15% of low-gluten flour, 13.5% of rice bran, 1.5% of soybean oil, 0.5% of sodium chloride, 0.2% of choline chloride, 0.04% of phytase, 1.5% of monocalcium phosphate, 0.2% of vitamin premix, 0.3% of trace element premix and 3.96% of gunite corn bran.

By adopting the technical scheme, the feed prepared from the obtained main material has low phosphorus content and high utilization rate through selection and adjustment of the mixture ratio of the raw materials, and is beneficial to reducing the addition of inorganic phosphorus in the feed, so that the raw material cost and phosphorus emission of the feed are reduced.

In a second aspect, the application provides a preparation method of an environment-friendly artificial mixed feed with low nitrogen and phosphorus emission, which adopts the following technical scheme:

a preparation method of an environment-friendly artificial compound feed with low nitrogen and phosphorus emission comprises the following steps:

step one, weighing main material raw materials according to a ratio, blending and crushing other components except phytase in the main material to obtain a medium product; and step two, adding water into the intermediate product, then carrying out expansion to obtain an expanded material, spraying the phytase aqueous solution obtained by water dilution on the surface of the expanded material, drying and screening to obtain the finished feed with the water content of 10-11.5%.

By adopting the technical scheme, the prepared feed is better in palatability and higher in digestibility due to the fact that the puffing process is adopted to process the feed, the feed is beneficial to improving the food intake and absorption efficiency of fish, the utilization efficiency of the feed is further exerted, and the emission of nitrogen and phosphorus is reduced.

Preferably, in the step one, the water content of the soybean meal, the rapeseed meal, the rice bran and the low-gluten flour is measured before the main materials are blended and crushed; and in the second step, the adding amount of water is adjusted according to the water content determined in the first step so as to control the water content of the prepared finished feed to be 10-11.5%.

Through adopting above-mentioned technical scheme, adopt the survey in advance to major ingredient moisture content, the water consumption of adding in nimble adjustment to the fodder, and then make the water content of finished feed maintain at stable within range, help promoting feed quality stability.

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

1. because the phytase is used as one of the main raw materials, the phytase can be used for degrading phytic acid into inositol and inorganic phosphorus and releasing phosphorus chelated by the phytic acid and potential protein in vegetable protein raw materials, so that the utilization rate of the animal body to mineral substances can be improved, the activity of digestive enzymes in the body can be enhanced, the addition amounts of protein and monocalcium phosphate in the feed can be reduced on the premise of keeping or even improving the feed effect, and the effects of reducing nitrogen and phosphorus emission, reducing water body environmental pollution, reducing the feed coefficient and improving the feed utilization efficiency are achieved;

2. according to the application, choline chloride, vitamin premix and trace element premix are preferably mixed according to a specific example, a certain synergistic effect can be generated, the weight increasing effect is exerted to the greatest extent, and the utilization efficiency of the feed is further improved;

3. according to the method, the prepared feed is better in palatability and higher in digestibility due to the fact that the puffing process is adopted to process the feed, the food intake and the absorption efficiency of the fish are improved, the utilization efficiency of the feed is further exerted, and the emission of nitrogen and phosphorus is reduced.

Drawings

FIG. 1 is a bar graph of errors of the SPSS software analysis and processing of the test data No. 1-6 of the application, which shows the influence of phytase addition on the feeding rate of grass carp;

FIG. 2 is an error histogram which shows the influence of phytase addition on the weight gain of grass carp and is obtained by analyzing and processing test data No. 1-No. 6 of the test of the present application through SPSS software;

FIG. 3 is an error histogram which shows the influence of phytase addition on the specific growth rate of grass carp obtained by analyzing and processing the test data No. 1-No. 6 of the test of the present application by SPSS software;

FIG. 4 is an error histogram which shows the influence of phytase addition on the bait coefficient of grass carp and is obtained by analyzing and processing test data No. 1-No. 6 of the application through SPSS software;

FIG. 5 is a bar graph of errors of the SPSS software analysis and processing of the test data No. 1-No. 6 of the present application showing the effect of phytase addition on the efficiency ratio of grass carp protein;

FIG. 6 is a bar graph of errors of experiments No. 1-6 of the present application, which are analyzed and processed by SPSS software, showing the influence of different phosphorus levels on the feeding rate of grass carp when phytase is added;

FIG. 7 is a histogram of errors of experiments 1# -6# of the present application, which are analyzed and processed by SPSS software, showing the influence of different phosphorus levels on the weight gain of grass carp when phytase is added;

FIG. 8 is a bar graph of the error of SPSS software analysis of the test data No. 1-6 of the present application showing the effect of different phosphorus levels on the specific growth rate of grass carp when phytase is added.

Detailed Description

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

The vitamin premix related in the following contents adopts the vitamin premix feed of omnivorous fish 801 type of Beijing Dabei agricultural technology group member company; the microelement premix adopts a pre-mixed feed of the F0311 type of the omnivorous fish of Beijing Dabei agricultural technology group member company; the soybean meal adopts 43 soybean meals, and the other raw materials are all common commercial products.

Examples

Examples 1 to 4

The raw material components and the corresponding weights of the raw materials of the environment-friendly artificial compound feed with low nitrogen and phosphorus emission are shown in the table 1, wherein the phytase activity is 2500U/kg.

The preparation method comprises the following steps:

the steps of,

(1) Raw materials: screening and cleaning bean pulp, rapeseed meal and rice bran to remove impurities;

(2) primary crushing: respectively crushing the soybean meal, the rapeseed meal and the rice bran cleaned in the step (1), and crushing the materials to be sieved by a 40-mesh sieve to be more than 50 percent;

(3) primary burdening: weighing the bean pulp, the rapeseed meal, the rice bran and the low-gluten flour according to the proportion, measuring the water content of the bean pulp, the rapeseed meal, the rice bran and the low-gluten flour, and then uniformly mixing to obtain a first-level ingredient;

(4) and (3) secondary crushing: performing secondary crushing on the primary ingredients obtained in the step (3), and crushing until the proportion of the materials passing through a 80-mesh sieve is more than 80%;

(5) secondary burdening: adding soybean oil, sodium chloride, calcium dihydrogen phosphate, nutritional additives and leveling materials into the material subjected to secondary crushing in the step (4), and mixing and dispersing uniformly again to obtain a medium product;

step two, according to the water content measured in the step one, adding water into the product obtained in the step one, uniformly stirring, and then carrying out puffing, drying and screening, wherein the method specifically comprises the following steps:

(a) heating and puffing: heating the product after adding water and stirring uniformly to 95-100 ℃, tempering for 90s at the temperature, puffing, and then air cooling to room temperature to obtain an expanded material;

(b) drying: drying the puffed material obtained in the step (a) by hot air until the puffed material has no obvious soft particles, wherein the drying temperature is 95 +/-15 ℃, and no coke material or paste material is controlled;

(c) primary screening: screening the dried expanded material obtained in the step (b), and removing unqualified crushed particles and dust to obtain a primary screened material;

(d) cooling and secondary screening: cooling the primary screening material obtained in the step (c) by ventilation until the temperature of the primary screening material does not exceed 5 ℃ of room temperature, and screening out dust in the primary screening material by using a vibrating screen to obtain a secondary screening material;

(e) spraying phytase: diluting the weighed phytase into phytase aqueous solution by using water according to the proportion of 1:125, atomizing and spraying the prepared phytase aqueous solution onto the secondary screening material prepared in the step (d) to obtain a finished product material;

(f) and (3) screening and packaging for three times: and (e) screening the finished product material in the step (e) for the third time, removing damaged particles and powder which do not meet the processing requirements, quantitatively packaging to obtain the finished product feed, and freezing and storing.

The results of the measurement of the crude protein content and crude fat content of the feed materials are also shown in Table 1. In addition, ash content, crude protein, crude fat, calcium content, total phosphorus content, lysine Lys content and methionine Met content of the finished feed were also measured, and the processed measurement data are shown in Table 2.

Table 1 examples 1-4 feed information table

Table 2 examples 1-4 feed nutrient analysis table

Test treatment	Example 1	Example 2	Example 3	Example 4
					Ash content	9.612	10.255	10.589	11.118
Crude protein	31.898	29.843	27.612	25.625
					Crude fat	4.644	4.557	5.396	4.552
Calcium carbonate	0.779	0.691	0.651	0.747
					Total phosphorus	1.386	1.318	1.262	1.163
Lysine Lys	1.685	1.587	1.511	1.286
					Methionine Met	0.49	0.441	0.398	0.327

Examples 5 to 9

An environment-friendly artificial mixed feed with low nitrogen and phosphorus emission is different from the artificial mixed feed in example 1 in that the raw materials and the corresponding weights thereof are shown in Table 3. In addition, ash content, crude protein, crude fat, calcium content and total phosphorus content in the finished feed were measured, and the processed measurement data are shown in table 4.

Table 3 feed information tables of examples 5 to 9

Table 4 examples 5-9 feed nutrient analysis table

Test treatment	Example 5	Example 6	Example 7	Example 8	Example 9
						Ash content	8.697	8.329	8.011	7.65	7.405
Crude protein	31.148	31.342	31.222	31.286	31.106
						Crude fat	4.567	4.688	4.686	4.707	5.179
Calcium carbonate	0.938	0.818	0.73	0.651	0.576
						Total phosphorus	1.588	1.456	1.357	1.264	1.147

Examples 10 to 12

An environment-friendly artificial mixed feed with low nitrogen and phosphorus emission is different from the feed in example 1 in that the dosages of choline chloride, vitamin premix and trace element premix are different, and the specific weights are shown in Table 5.

TABLE 5 corresponding amounts of choline chloride, vitamin premix and trace element premix in examples 10-12

	Example 10	Example 11	Example 12
				Choline chloride (kg)	5	1	1
Vitamin premix (kg)	1	5	1
				Microelement premix (kg)	1	1	5

Comparative example

Comparative example 1

An artificial mixed feed, which is different from the artificial mixed feed in example 1 in that the main raw material does not contain phytase, the specific raw material components and the corresponding weight thereof are shown in table 6, the ash content, the crude protein, the crude fat, the calcium content, the total phosphorus content, the lysine Lys content and the methionine Met content of the finished feed are detected, and the processed detection data are shown in table 7.

Comparative example 2

Compared with the comparative example 1, the difference of the artificial formula feed is that the main raw materials also comprise L-lysine hydrochloride and DL-methionine, the specific raw material components and the corresponding weight are shown in table 6, the ash content, the crude protein, the crude fat, the calcium content, the total phosphorus content, the lysine Lys content and the methionine Met content of the finished feed are detected, and the processed detection data are shown in table 7.

Comparative example 3

Compared with the comparative example 1, the artificial formula feed is characterized in that bentonite in the main material raw materials is replaced by sprayed corn bran, specific raw material components and corresponding weight of the components are shown in table 6, ash content, crude protein, crude fat, calcium content and total phosphorus content of the finished feed are detected, and processed detection data are shown in table 7.

TABLE 6 feed information tables for comparative examples 1-3

	Comparative example 1	Comparative example 2	Comparative example 3
				Bean pulp (kg)	300	300	300
Rapeseed meal (kg)	348	334.5	348
				Low-gluten flour (kg)	150	150	150
Rice bran (kg)	135	135	135
				Soybean oil (kg)	15	15.2	15
Sodium chloride (kg)	5	5	5
				L-lysine hydrochloride (kg)	/	4	2
DL-methionine (kg)	/	2	/
				Choline chloride (kg)	2	2	2
Calcium dihydrogen phosphate (kg)	20	20	30
				Vitamin premix (kg)	2	2	2
Microelement premix (kg)	3	3	3
				Bentonite (kg)	20	27.3	/
Spray-grouting corn peel (kg)	/	/	10
				Total up to	1000	1000	1000
Moisture (%)	10.84	10.77	10.76
				Crude protein (%)	29.98	29.99	30.16
Crude fat (%)	5.17	5.16	5.20

TABLE 7 analysis table of nutrient components of comparative examples 1 to 3

Performance test

Experiment-study of the Effect of adding Phytase to Low protein feed

An experimental system: indoor circulating water culture system

And (3) test period: 60 days

And (3) experimental fish: the grass carp has the average weight of 185 g/tail and 25 tails/cylinder

Feeding: satiation feeding, 2 treatment groups/day: the feed of comparative example 1 was used in the group # 1, the feed of comparative example 2 was used in the group # 2, and the feed of examples 1 to 4 was used in the group # 3 to 6. Namely, 30% of crude protein content in the group 1, 30% of crude protein content in the group 2 + lysine + methionine, 30% of crude protein content in the group 3 + phytase, 28% of crude protein content in the group 4 + phytase, 26% of crude protein content in the group 5 + phytase, and 24% of crude protein content in the group 6 + phytase, and the addition amounts of the phytases are the same.

In addition, the ratio of choline chloride, vitamin premix and trace element premix was investigated using the 7-9# group of the feeds of examples 10-12.

The number of repetitions: 5

And (3) test results: the experimental data and the ingestion rate, the weight gain rate and the specific growth rate calculated according to the experimental data are shown in table 8, error bar charts of the ingestion rate, the weight gain rate, the specific growth rate, the feed coefficient and the protein efficiency ratio obtained by analyzing and processing data # 1-6 in table 8 through SPSS software are shown in fig. 1-5, marked a, b, c and d in the graphs represent Y-axis differences, the same letters indicate that the differences are not significant, and all results in fig. 4 do not have significant differences and are not marked.

Table 8 test a test result and associated data record table

And (4) analyzing results:

the test results of the comparative examples 1-2, the examples 1-4 and the first test show that the raw material proportion setting test in the main material is adjusted under the condition that the total feed amount is kept unchanged and the crude protein content and the crude fat content are basically consistent, and the performances of the feeds of the comparative examples 1-2 are similar in all aspects as shown in the table 8 and the figures 1-3, which indicates that the influence of protein in the feeds on the protein absorption is not large no matter whether the protein is combined protein or free protein; the grass carp fed by the feed of the group # 1-4, namely the comparative example 1-2 and the example 1-2, has higher ingestion rate, weight gain rate and specific growth rate, and is a better proportioning scheme; furthermore, as can be seen from fig. 4, the difference of the feed factors of the groups 1 to 6 is not obvious, and as can be seen from fig. 5, the protein efficiency ratios fed by the feeds of examples 2 to 4 are obviously improved compared with the protein efficiency ratios fed by the feeds of comparative examples 1 to 2, which indicates that the phytase dosage has a direct influence on the protein efficiency ratio at a specific ratio, while the protein efficiency ratio of the group 4 in the groups 1 to 4 is obviously improved, so that the ratio in the group 4, i.e., in example 2, is the optimal ratio of the low-protein feed.

By combining the test results of the example 1, the examples 10 to 12 and the first test, it can be seen that the weight gain rate and the specific growth rate of the grass carp can be remarkably improved by adopting the specific mixing ratio of the choline chloride, the vitamin premix and the trace element premix.

Experiment on influence of phytase added in low-phosphorus feed

An experimental system: indoor recirculating aquaculture system

And (3) test period: 69 days

And (3) experimental fish: grass carp is 125 g/tail, 25 tail/jar

Feeding: satiation feeding, 2 treatment groups/day: the feed of comparative example 3 was used in group 1, and the feed of examples 5-9 was used in group 2-6, i.e., the raw material crude protein content of group 1-6 was 30% for each of group 1-6, where group 1 had no phytase added to 3% monocalcium phosphate, group 2.5% monocalcium phosphate + phytase, group 3 had 2% monocalcium phosphate + phytase, group 4 had 1.5% monocalcium phosphate + phytase, group 5 had 1% monocalcium phosphate + phytase, and group 6 had 0.5% monocalcium phosphate + phytase.

The number of repetitions: 5

And (3) test results: the experimental data and the calculated feeding rate, weight gain rate and specific growth rate according to the experimental data are shown in table 9, the error bar charts of the feeding rate, weight gain rate and specific growth rate obtained by analyzing and processing the data in table 9 by SPSS software are shown in fig. 6-8, marked a, b, c and d in the graphs represent the Y-axis difference, and the marked letter is identical and the mark is not obvious.

TABLE 9 test results of the second test and the related data record table

And (4) analyzing results:

in combination with the test results of comparative example 3, examples 5 to 9 and test two, it can be seen that, under the condition of keeping the total feed amount unchanged and the crude protein content and crude fat content substantially consistent, the amount of the phosphorus-containing component in the main material is mainly adjusted, and in combination with table 9 and fig. 6, the grass carp fed by the feed of the group 4 to 6, namely examples 7 to 9, has a higher feeding rate, and is a better proportioning scheme, so that the phytase is beneficial to improving the feeding rate of the grass carp under a specific proportioning condition, and further, in combination with fig. 7 to 8, the feed of the group 4, namely example 7, has the most obvious improvement on a specific growth rate and weight gain rate, and can effectively reduce phosphorus emission in comprehensive consideration, so the proportioning of the feed of the group 4 in the test two, namely example 7, is the optimal low-phosphorus feed.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The environment-friendly artificial mixed feed with low nitrogen and phosphorus emission is characterized by being prepared from main materials and water, wherein the main materials are prepared from the following raw materials in percentage by weight: 28-30% of soybean meal, 9.8-34.8% of rapeseed meal, 15-36.2% of low-gluten flour, 13-14% of rice bran, 1.5-1.67% of soybean oil, 0.45-0.55% of sodium chloride, 0.5-3% of monocalcium phosphate, 0.58-0.82% of nutritional additives, 0.03-0.05% of phytase and the balance of leveling materials; the crude protein content of the main material raw material is 24% -30.2%;

the phytase activity is 2400-2600U/kg.

2. The environment-friendly artificial mixed feed with low nitrogen and phosphorus emission according to claim 1, which is characterized in that: the leveling material is bentonite or gunite corn bran.

3. The low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in claim 2, wherein: the nutritional additive comprises choline chloride, vitamin premix and trace element premix.

4. The low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in claim 3, which is characterized in that: based on the total weight of the main materials, the nutritional additive comprises the following raw materials in percentage by weight: 0.18 to 0.22 percent of choline chloride, 0.15 to 0.25 percent of vitamin premix and 0.25 to 0.35 percent of trace element premix.

5. The low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in claim 4, which is characterized in that: the main material is prepared from the following raw materials in percentage by weight: 30% of soybean meal, 26.5% of rapeseed meal, 22.16% of low-gluten flour, 13.5% of rice bran, 1.55% of soybean oil, 0.5% of sodium chloride, 0.2% of choline chloride, 0.04% of phytase, 2% of monocalcium phosphate, 0.2% of vitamin premix, 0.3% of trace element premix and 3.05% of bentonite.

6. The low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in claim 4, which is characterized in that: the main material is prepared from the following raw materials in percentage by weight: 30% of soybean meal, 33.3% of rapeseed meal, 15% of low-gluten flour, 13.5% of rice bran, 1.5% of soybean oil, 0.5% of sodium chloride, 0.2% of choline chloride, 0.04% of phytase, 1.5% of monocalcium phosphate, 0.2% of vitamin premix, 0.3% of trace element premix and 3.96% of guniting corn husk.

7. The preparation method of the low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in any one of claims 1 to 6, which is characterized in that: the method comprises the following steps:

step one, weighing main material raw materials according to a ratio, blending and crushing other components except phytase in the main material to obtain a medium product;

and step two, adding water into the intermediate product, then carrying out expansion to obtain an expanded material, spraying the phytase aqueous solution obtained by water dilution on the surface of the expanded material, drying and screening to obtain the finished feed with the water content of 10-11.5%.

8. The preparation method of the low nitrogen phosphorus emission environment-friendly artificial mixed feed as claimed in claim 7, wherein the preparation method comprises the following steps: in the first step, the water content of the soybean meal, the rapeseed meal, the rice bran and the low-gluten flour is required to be measured before the main materials are blended and crushed; and in the second step, the adding amount of water is adjusted according to the water content determined in the first step so as to control the water content of the prepared finished feed to be 10-11.5%.