APPLICATION OF ASPARTIC ACID DERIVATIVE IN PREPARING ANIMAL FEED ADDITIVE

Abstract

Disclosed is use of an aspartic acid derivative having a structure represented by formula (I), or a racemate, stereoisomer, geometric isomer, tautomer, solvate or feed-acceptable salt thereof, in preparing an animal feed additive that significantly improves production performance of farmed animals,

##STR00001##

wherein Y and X are independently selected from a C.sub.1-C.sub.20 alkyl or —H; R.sup.1 is R.sup.1aC(═O) or H; R.sup.2 is R.sup.2aC(═O); and the R.sup.1a and R.sup.2a are independently selected from (A)(B)N—(CH.sub.2).sub.0-5—, and the A and B are independently selected from a C.sub.1-C.sub.20 alkyl or —H.

Claims

1. An aspartic acid derivative having a structure represented by the following general formula, or a racemate, stereoisomer, geometric isomer, tautomer, solvate or feed-acceptable salt thereof, for use in preparing an animal feed additive: ##STR00010## wherein R.sup.1 is R.sup.1aC(═O)— or —H; R.sup.2 is R.sup.2aC(═O)—; the R.sup.1a and R.sup.2a are independently selected from (A)(B)N—(CH.sub.2).sub.0-5—, and the A and B are independently selected from a C.sub.1-C.sub.20 alkyl or —H; and Y and X are independently selected from a C.sub.1-C.sub.20 alkyl or —H.

2. The aspartic acid derivative according to claim 1, wherein the R.sup.1 in the aspartic acid derivative is —H.

3. The aspartic acid derivative according to claim 1, wherein the A and B in the aspartic acid derivative are —H at the same time.

4. The aspartic acid derivative according to claim 1, wherein the Y and X in the aspartic acid derivative are —H.

5. The aspartic acid derivative according to claim 1, wherein the Y and X in the aspartic acid derivative are independently selected from a C.sub.1-C.sub.20 alkyl or —H, and are not —H at the same time.

6. The aspartic acid derivative according to claim 5, wherein the Y and X in the aspartic acid derivative are independently selected from a C.sub.1-C.sub.4 alkyl or —H, and are not —H at the same time.

7. The aspartic acid derivative according to claim 1, wherein the feed-acceptable salt of the aspartic acid derivative is a metal ion salt.

8. The aspartic acid derivative according to claim 7, wherein the metal ion salt is a sodium ion salt, a zinc ion salt, a copper ion salt, an iron ion salt, or a calcium ion salt.

9. A feed composition comprising at least one of the aspartic acid derivative according to claim 1, and an auxiliary material usable for feed.

10. The feed composition according to claim 9, wherein the feed composition further comprises an additional animal feed additive, and the additional animal feed additive is selected from a nutritional feed additive, a non-nutritional feed additive or a medicinal feed additive.

11. The feed composition according to claim 9, wherein the feed composition further comprises an animal feed raw material.

12. The feed composition according to claim 9 for use in preparing an animal feed additive.

13. The feed composition according to claim 9 for use in preparing an animal feed.

14. The feed composition according to claim 10, wherein the feed composition further comprises an animal feed raw material.

15. The feed composition according to claim 10 for use in preparing an animal feed additive.

16. The feed composition according to claim 11 for use in preparing an animal feed additive.

17. The feed composition according to claim 14 for use in preparing an animal feed additive.

18. The feed composition according to claim 10 for use in preparing an animal feed.

19. The feed composition according to claim 11 for use in preparing an animal feed.

20. The feed composition according to claim 14 for use in preparing an animal feed.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0160] To make the objects, the technical solution, and advantages of the present invention clearer, the compounds, the combinations, and the use of the present invention are described in further detail with reference to examples. It should be understood that the specific embodiments described herein are merely used for explaining the present invention, and are not intended to limit the present invention.

Example 1: Preparation of Compounds

Example 1.1 Preparation of N-carbamoyl-DL-aspartic Acid

[0161] ##STR00008##

[0162] 13 g of DL-aspartic acid and 8 g of potassium cyanate were dissolved in 100 mL of 1 mol/L potassium hydroxide solution at room temperature with stirring at room temperature for 16 h, and the reaction mixture was adjusted to pH 2 with concentrated hydrochloric acid, and then stirred for 1.0 h to precipitate a solid, which was filtered and slurried with water to give 10.5 g of white solid. The yield was 68%. .sup.1H NMR (500 MHz, DMSO-d.sub.6) δ: 12.48 (s, 2H), 6.28 (d, 1H), 5.72 (s, 2H), 4.35-4.38 (m, 1H), 2.56-2.67 (m, 2H).

Example 2 Preparation of N-glycyl-DL-aspartic Acid

[0163] ##STR00009##

[0164] 1.1 g of N-Boc-glycine, 1.6 g of di-tert-butyl DL-aspartate and 2.6 g of HBTU were dissolved in 15 mL of dry DMF, and diisopropylethyl amine was added under the protection of nitrogen and the resulting reaction mixture was reacted overnight at room temperature. After the reaction, 100 mL of ethyl acetate was added to the reaction mixture, and the resulting organic phase was washed sequentially with 30 mL of 1N sodium bicarbonate solution and 30 mL of 1N hydrochloric acid aqueous solution, and then dried over magnesium sulfate. The organic solvent was removed by rotary evaporation and the crude product obtained was purified by a silica gel column chromatography (dichloromethane/methanol (v:v)=96:5) to give 1.5 g of di-tert-butyl N—(N-Boc-glycyl)-aspartate. The yield was 60%.

[0165] The di-tert-butyl N—(N-Boc-glycyl)-aspartate obtained in the above step was dissolved in 100 mL of dry dichloromethane, 8 mL of trifluoroacetic acid was added, stirred at room temperature and reacted for 24 h, and then washed with water (50 mL×3), followed by reduced pressure and concentration to remove the solvent. The obtained crude product was recrystallized in ethyl acetate to obtain 0.6 g of N-glycyl-DL-aspartic acid, with a yield of 72.7%.

Example 2: Test for Studying the Thermal Stability of Compounds

[0166] The variations of the contents of the main ingredient of the aspartic acid derivative raw material and the main ingredient of a premix containing 2% mass fraction of the aspartic acid derivative (hereinafter referred to as 2% premix) over time were investigated under the conditions of stability test at 60° C.

[0167] Experimental apparatus: drug stability incubator, Waters high-performance liquid chromatograph (HPLC), etc.

[0168] Test samples: N-carbamoyl-DL-aspartic acid (compound 1), diethyl N-carbamoyl-DL-aspartate (compound 2), Sodium N-carbamoyl-DL-aspartate (compound 3), Calcium N-carbamoyl-DL-aspartate (compound 4), Zinc N-carbamoyl-DL-aspartate (compound 5), Copper N-carbamoyl-DL-aspartate (compound 6), Iron N-carbamoyl-DL-aspartate (compound 7), N-glycyl-DL-aspartic acid (compound 8), N-(4-aminobutyryl)-DL-aspartic acid (compound 9), N-(10-aminodecanoyl)-DL-aspartic acid (compound 10), N-(14-aminomyristoyl)-DL-aspartic acid (compound 11).

[0169] Experimental reagents: methanol (chromatographic grade), phosphoric acid (analytically pure).

[0170] Experimental Steps:

[0171] Preparation of standard solution: 50 mg of the test sample raw material was ultrasonically dissolved in 50 mL of water to obtain a working reserve solution. An appropriate amount of the working reserve solution was taken and diluted with water respectively to concentrations of 125 ppm, 250 ppm, 500 ppm, and 1000 ppm for HPLC testing. It was checked whether the sample concentrations are in a linear relationship with the peak area response values in HPLC, and a standard curve was established.

[0172] Preparation of test solution: An appropriate amount of the test sample raw material and an appropriate amount of a premix containing 2% mass fraction of the test sample (hereinafter referred to as 2% premix) were separately ultrasonically dissolved in an appropriate amount of water to form a 1000 ppm solution, which is filtered through a 0.22 μm filter membrane and then analyzed by HPLC.

[0173] HPLC analysis conditions: chromatographic column: Waters C18 column (250 mm×4.6 mm, 5 μm); mobile phase: 0.05% phosphoric acid:methanol=95:5 (v:v) (raw material); 0.05% phosphoric acid: methanol (gradient elution); methanol: 5%-40% (0-15 min) curve 6, 40%.fwdarw.5% (15-16 min) curve 1, 5% (16-23 min) curve 1, (premix, feed); detection wavelength: 210 nm; column temperature: 25° C.; sample size: 20 μL; flow rate: 1 mL/min.

[0174] Test method: The test sample raw material and its 2% premix were placed in a culture plate, spread into a thin layer of <5 mm, and placed at 60° C. Samples were taken on the day 5 and day 10 for HPLC detection. Each sample was sampled three times in parallel.

[0175] Test results: The test results are expressed as “mean values”, as shown in Table 1. The test results show that in the test period of 0-10 days, except that the content of the Iron N-carbamoyl-DL-aspartate dropped to 94.98% on the 10.sup.th day, the contents of the raw material of each test sample and its 2% premix did not change significantly under high temperature conditions at 60° C., exhibiting excellent stability.

TABLE-US-00001 TABLE 1 Study on the thermal stability of compounds Detection result of the content of test sample (%) Test sample Dosage form Day 5 Day 10 Compound 1 Raw material 99.79 99.28 2% premix 99.66 99.70 Compound 2 Raw material 97.32 96.97 2% premix 98.81 98.09 Compound 3 Raw material 103.02 103.53 2% premix 99.33 99.21 Compound 4 Raw material 101.54 101.87 2% premix 98.93 97.99 Compound 5 Raw material 99.76 98.47 2% premix 96.89 96.36 Compound 6 Raw material 99.91 98.31 2% premix 98.28 97.94 Compound 7 Raw material 97.63 96.01 2% premix 96.74 94.98 Compound 8 Raw material 99.78 98.02 2% premix 98.57 97.32 Compound 9 Raw material 98.46 98.09 2% premix 99.41 97.68 Compound 10 Raw material 99.00 96.73 2% premix 98.55 97.81 Compound 11 Raw material 97.61 95.93 2% premix 98.22 97.80 Note: Characterization method for detection result of the content of test sample: The detection result of the content of the test sample is obtained by comparing the result of measurement performed by an instrument on the test sample sample at a specific time in each test with the measurement result obtained on Day 0, where if the detection result of the content changes by 5% or more, it is determined that a significant change occurs.

Example 3: Breeding Test

[0176] Example 3.1 The effect of the aspartic acid derivative and salt thereof on the production performance of weaned piglets

[0177] From 95 litters of 28±2 days old Duroc X Landrace X Yorkshire cross-bred weaned piglets, 360 clinically healthy piglets with similar body weights were selected as test pigs, which were randomly divided into 12 groups, with 3 replications per group and 10 pigs (half of male and female) per replication. The piglets were attracted to the food trough at the age of 7 days, and the hog house for 28-day-old weaned pigs has a cement floor, steel fence, good ventilation, and suitable temperature. The pigpens and utensils were sterilized before the test. During the test period, the test pigs were free-stall housed in the same pigpen under the same feeding and management conditions, and were free to drink water and eat feed. The hog house was cleaned once a day, and the floor is washed once every three days to maintain clean and hygienic conditions. The test pigs were fed three times a day. The test groups include control and test groups. Group I is the control group, in which only the basal daily ration was fed to the piglets. 50 ppm of the aspartic acid derivative was added into the basal daily ration for the piglets in the test groups II-VII, as shown in Table 2. 1000 ppm of a the aspartic acid derivative metal ion salt was added into the basal daily ration for the piglets in the groups VIII-XII, as shown in Table 2. No other antioxidant ingredients or growth promoters were added for the test groups during the entire feeding process. The test period was 40 days.

[0178] The test pigs were weighed during 7:00 to 9:00 in the morning of Day 0 and Day 40 after the start of the test. During the test period, the feed intake and health status of the piglets were observed every day, the remaining daily ration was weighed, the feed consumption was recorded, and the average daily feed intake (ADFI, g/d*each pig), the average daily gain (ADG, g/d*each pig), and the feed conversion ratio (FCR) were calculated. Calculation formulas are as follows:

Average daily feed intake=(total amount of feed−remaining amount of feed)/(number of days of test×number of pigs per repetition);

Average daily gain=(average body weight at the end of the test−average body weight at the beginning of the test)/number of days of test;

[0179] Feed conversion ratio=average daily feed intake/average daily gain.

[0180] The test data was statistically analyzed using SPSS18 software. First, a one-way analysis of variance (ANOVA) was performed on the data. If the difference between treatments is significant, Duncan's method was used for multiple comparisons, and the significance level was 0.05. The test results are expressed as “mean value±standard deviation”, and are as shown in Table 2.

[0181] It can be seen from the results of the feeding tests for weaned piglets that by comparison between the test groups and the control group, all the test samples except diethyl N-carbamoyl-DL-aspartate, Sodium N-carbamoyl-DL-aspartate and Zinc N-carbamoyl-DL-aspartate have no obvious impact on the feed intake of weaned pigs. In terms of average daily gain, N-carbamoyl-DL-aspartic acid, N-glycyl-DL-aspartic acid, and N-(4-aminobutyryl)-DL-aspartic acid increased the average daily gain of the test pigs by 7.0%, 5.2%, 8.1% respectively, which, however, are not significant compared with that of the control group. The other test groups had a significant effect in increasing the average daily gain of the test pigs compared with the control group. In terms of feed conversion rate, the feed conversion rates of each test group decreased by 4.8%-7.8%, and there was no significant improvement effect compared with the control group.

TABLE-US-00002 TABLE 2 Study on the effect of aspartic acid derivatives and their salts on the production performance of weaned piglets ADFI ADG Test sample/content: (ppm) (g/d*each pig) (g/d*each pig) FCR Group I — 310 ± 18.sup.a 135 ± 4.sup.a  2.29 ± 0.07 Group II N-carbamoyl-DL-aspartic acid 45 315 ± 14.sup.a .sup. 145 ± 10.sup.abc 2.18 ± 0.05 Group III N-glycyl-DL-aspartic acid 45 305 ± 12.sup.a 142 ± 1.sup.ab 2.15 ± 0.07 Group IV N-(4-aminobutyryl)-DL-aspartic acid 45 311 ± 18.sup.a  146 ± 4.sup.abc 2.13 ± 0.06 Group V N-(10-aminodecanoyl)-DL-aspartic acid 45 321 ± 7.sup.a  150 ± 1.sup.bc 2.14 ± 0.06 Group VI N-(14-aminomyristoyl)-DL-aspartic acid 45 322 ± 16.sup.a 150 ± 4.sup.bc 2.14 ± 0.05 Group VII diethyl N-carbamoyl-DL-aspartate 45 374 ± 11.sup.b 176 ± 2.sup.d  2.13 ± 0.05 Group VIII Sodium N-carbamoyl-DL-aspartate 1000 .sup. 388 ± 11.sup.bc 182 ± 2.sup.d  2.13 ± 0.04 Group IX Calcium N-carbamoyl-DL-aspartate 1000 333 ± 8.sup.a  157 ± 0.sup.c  2.13 ± 0.05 Group X Zinc N-carbamoyl-DL-aspartate 1000 418 ± 19.sup.c 198 ± 3.sup.6  2.11 ± 0.07 Group XI Copper N-carbamoyl-DL-aspartate 1000 329 ± 13.sup.a 156 ± 1.sup.c  2.11 ± 0.07 Group XII Iron N-carbamoyl-DL-aspartate 1000 330 ± 11.sup.a 153 ± 1.sup.bc 2.15 ± 0.06 Note: Data in the same column labeled with different letters indicates a significant difference (P < 0.05)

[0182] Example 3.2 The effect of the aspartic acid derivative and salt thereof on the production performance of laying hens

[0183] The test adopted a single-factor random design. 420 147-day-old Jingbai laying hens with similar body weights were selected and randomly divided into 7 treatment groups, with 3 replications per group and 20 Jingbai laying hens (half of male and female) per replication. The poultry houses and utensils were sterilized before the test. During the test period, the Jingbai laying hens were cage cultured in the same laying poultry house under the same feeding and management conditions. The basal daily ration was mainly corn-soybean meal, and no other antioxidant ingredients or growth promoters were added additionally during the entire feeding process. The test groups include a control group and test groups I-VII. The basal daily ration was fed for the control group I only, and 500 ppm of different aspartic acid derivatives were added into the basal daily ration for the test groups II-VII, as shown in Table 3. The pre-feeding period was 10 days, and the test period was 158 days. The test laying hens were free to drink water and eat feed, and were fed twice a day.

[0184] Parameter statistics: During the test period, taking each repetition as a unit, the total egg number, the egg production, and the feed intake were recorded every day, and the egg production rate (EPR), the average daily feed intake (ADFI, g/d), the egg weight (EW, g) and the feed-to-egg ratio (FER) of the laying hens during the entire test were calculated.

[0185] Calculation formulas are as follows:

Egg production rate (%)=average daily total egg number/number of laying hens×100;

Egg weight(g)=average daily total egg weight/average daily total egg number;

Feed-to-egg ratio=average daily feed intake/egg weight.

[0186] The test data was statistically analyzed using SPSS 18 software. First, a one-way analysis of variance (ANOVA) was performed on the data. If the difference between treatments is significant, Duncan's method was used for multiple comparisons, and the significance level was 0.05. The test results are expressed as “mean value±standard deviation”, and are as shown in Table 4.

[0187] It can be seen from the results that the effects of the test samples on the egg production rate and feed-to-egg ratio of the test laying hens were not significant compared with the control group, but reflected different degrees of improvement, where the egg production rate was increased by 2.7%-4.4% and the feed-to-egg ratio was decreased by 5.9%-7.6%; the test samples had no effect on the feed intake of the test laying hens, but the egg weights of all the groups except N-glycyl-DL-aspartic acid were increased significantly.

TABLE-US-00003 TABLE 3 Test groups of use of aspartic acid derivatives in feeds for laying hens Content Test sample (ppm) Group I — — Group II N-carbamoyl-DL-aspartic acid 500 Group III N-glycyl-DL-aspartic acid 500 Group IV N-(4-aminobutyryl)-DL-aspartic acid 500 Group V N-(10-aminodecanoyl)-DL-aspartic acid 500 Group VI N-(14-aminomyristoyl)-DL-aspartic acid 500 Group VII diethyl N-carbamoyl-DL-aspartate 500

TABLE-US-00004 TABLE 4 Study on the effect of use of aspartic acid derivatives in feeds for laying hens EPR (%) ADFI (g/d) EW (g) EPR Group 82.61 ± 0.17.sup.a 119.56 ± 1.21 54.23 ± 0.38.sup.a 2.21 ± 0.02.sup.a I Group 85.80 ± 0.14.sup.b 113.44 ± 1.55 55.49 ± 0.38.sup.b 2.04 ± 0.02.sup.b II Group 84.86 ± 0.24.sup.c 113.01 ± 2.31 54.98 ± 0.39.sup.a 2.06 ± 0.03.sup.b III Group 86.09 ± 0.18.sup.b 113.64 ± 2.43 55.44 ± 0.37.sup.b 2.05 ± 0.04.sup.b IV Group 85.24 ± 0.18.sup.c 119.31 ± 1.84 57.45 ± 0.47.sup.c 2.08 ± 0.03.sup.b V Group 85.24 ± 0.17.sup.c 115.13 ± 2.91 55.45 ± 0.35.sup.b 2.08 ± 0.04.sup.b VI Group 86.28 ± 0.20.sup.b 115.19 ± 3.14 55.94 ± 0.37.sup.b 2.06 ± 0.04.sup.b VII Note: Data in the same column labeled with different letters indicates a significant difference (P < 0.05)

[0188] Example 3.3 The effect of the aspartic acid derivative and salt thereof on the production performance of broilers

[0189] The test adopted a single-factor random design. 420 1-day-old yellow-feathered broilers with similar body weights and having an average weight of 50 g were selected and randomly divided into 7 treatment groups, with 3 replications per group and 20 yellow-feathered broilers (half of male and female) per replication. The poultry houses and utensils were sterilized before the test. During the test period, the Jingbai laying hens were cage cultured in the same laying henhouse under the same feeding and management conditions. The basal daily ration was mainly corn-soybean meal, and no other antioxidant ingredients or growth promoters were added additionally during the entire feeding process. The test groups include a control group and test groups I-VII. The basal daily ration was fed for the control group I only, and 300 ppm of different aspartic acid derivatives were added into the basal daily ration for the test groups II-VII, as shown in Table 5. The test period was 20 days. The test yellow-feathered broilers were free to drink water and eat feed, and were fed twice a day. Taking each repetition as a unit, the test broilers were weighed at the age of 21 days (where provisioning of feeds was stopped for 12 hours, but provisioning of water was not stopped), the feed consumption of the test broilers were calculated, and the average daily feed intake (ADFI, g/d*each broiler), the average daily gain (ADG, g/d*each broiler) and the feed conversion ratio (FCR) were calculated for the test broilers of each group. Calculation formulas are as follows:

Feed conversion ratio(FCR)=average daily feed intake/average daily gain.

[0190] The test data was statistically analyzed using SPSS18 software. First, a one-way analysis of variance (ANOVA) was performed on the data. If the difference between treatments is significant, Duncan's method was used for multiple comparisons, and the significance level was 0.05. The test results are expressed as “mean value±standard deviation”, and are as shown in Table 5.

[0191] It can be seen from the results that the effects of the aspartic acid derivative test samples in the test groups on the feed intake have different degrees of improvement compared with the control group; compared with the control group, the average daily gains of the test broilers in the test groups were all increased, wherein the effects of N-carbamoyl-DL-aspartic acid and diethyl N-carbamoyl-DL-aspartate were the most significant; in terms of feed conversion ratio, compared with the control group, the feed conversion ratios of the test groups were decreased by about 3.1% to 7.0%, and significant improvement effects were observed in some test groups. On the whole, the aspartic acid derivatives used in the tests have excellent effects on the improvement of production performance of broilers both in terms of average daily gain and feed conversion ratio.

TABLE-US-00005 TABLE 5 Study on the effect of use of aspartic acid derivatives in feeds for broilers ADFI ADG (g/d*each (g/d*each Test sample/content: (ppm) broiler) broiler) FCR Group I — 34.63 ± 0.71.sup.a 13.48 ± 0.14.sup.a 2.57 ± 0.03.sup.a Group II N-carbamoyl-DL-aspartic acid 300 38.83 ± 0.53  16.59 ± 0.14.sup.b 2.34 ± 0.03.sup.b Group III N-glycyl-DL-aspartic acid 300 36.05 ± 0.83.sup.b 14.48 ± 0.24.sup.b  2.49 ± 0.03.sup.ab Group IV N-(4-aminobutyryl)-DL-aspartic acid 300 37.92 ± 0.53.sup.c 15.84 ± 0.10.sup.b 2.39 ± 0.04.sup.b Group V N-(10-aminodecanoyl)-DL-aspartic acid 300 34.82 ± 0.64.sup.a 14.40 ± 0.15.sup.b 2.42 ± 0.04.sup.b Group VI N-(14-aminomyristoyl)-DL-aspartic acid 300  36.70 ± 0.54.sup.ac 15.02 ± 0.13.sup.b 2.44 ± 0.04.sup.b Group VII diethyl N-carbamoyl-DL-aspartate 300 40.05 ± 0.81.sup.d 16.81 ± 0.68.sup.b 2.39 ± 0.05.sup.b Note: Data in the same column labeled with different letters indicates a significant difference (P < 0.05).

[0192] Table 3.4 Use of aspartic acid derivatives in feeds for fish

[0193] 1) Test Materials

[0194] Test fish: The test fishes used were healthy and lively grass carp fingerlings with uniform size, which were fed in large cages for 4 weeks before being used for formal breeding test. The experimental system was a small floating cage (specification: 1.1×1.1×1.1 m.sup.3), each small floating cage being equipped with an aeration head, providing aeration 24 h a day. Both the small floating cage and the temporary cage were placed in a 3500 m.sup.2 pond of the test field, the depth of the pond was about 1.5 m, and the water of the pond was fully aerated in the bottom of the pond. 560 grass carps that were hungry for 1 day were randomly divided into 7 groups, with 4 replications per group and 20 grass carps per replication. By taking each replication as a unit, all of the grass carps were weighed, and then placed in 28 cages and fed with test feeds containing different test samples at the same content level.

[0195] Test feeds: The feeds for the test were self-prepared based on the formulations in Table 6, and different test samples were added at the same content level for different test groups according to Table 7, respectively.

[0196] The feed raw materials used were ground by ultrafine grinding and fed into a puffing machine produced by Jiangsu Muyang Group Co., Ltd. to make 3 mm floating puffed feed, where the mold clearing temperature was 130° C., 3% soybean oil was sprayed using an oil spraying equipment, and the obtained feed was sealed and stored in a cool place for later use.

TABLE-US-00006 TABLE 6 Formulations and chemical compositions of test feeds for grass carps (wt. %) Raw material Content Raw material Content composition (%) composition (%) Fish meal 9.0 Soybean oil 3.0 Casing powder 3.0 Phospholipid 9.0 rapeseed meal Soybean meal 12.0 Wheat gluten powder 4.0 Rapeseed meal 12.0 Blood cell powder 2.0 Monosodium 3.0 Vc-phosphate 0.1 glutamate protein Brown shorts 12.6 Calcium dihydrogen 1.8 phosphate Flour 17.0 Choline chloride 0.2 Bentonite 0.70 Multi-vitamin premix 0.1 Rice bran 10.0 Trace-mineral premix 0.5

TABLE-US-00007 TABLE 7 Test groups for the study of use of aspartic acid derivatives in feeds for fish Dose Group Test sample (ppm) Group I — — Group II N-carbamoyl-DL-aspartic acid 3000 Group III N-glycyl-DL-aspartic acid 3000 Group IV N-(4-aminobutyryl)-DL-aspartic acid 3000 Group V N-(10-aminodecanoyl)-DL-aspartic acid 3000 Group VI N-(14-aminomyristoyl)-DL-aspartic acid 3000 Group VII diethyl N-carbamoyl-DL-aspartate 3000

[0197] (2) Test Method

[0198] Test management: The test adopted controlled artificial feeding, and the feeding amount was adjusted once a week. The feeding levels for all the groups (based on the initial fish weight) were exactly the same, and the grass carps were fed twice a day (7:30 and 15:00). The total feeding amount was 580 g/replication test group. The test period was 8 weeks. During the test, the water quality was regularly monitored. The water temperature during the whole breeding process was 26.88±3.08° C., DO>5.0 mg O L.sup.−1, pH 7.8, ammonia nitrogen<0.50 mg N L.sup.−1, nitrite nitrogen<0.05 mg N L.sup.−1.

[0199] Parameter statistics: During the test, after the provisioning of feeds has been stopped for 1 day, fishes in each cage were weighed as a whole, and the weight gain (WG, %) and the feed conversion ratio (FCR) were calculated. Calculation formulas are as follows:

Weight gain(WG,%)=100×(average final weight−average initial weight)/average initial weight;

Feed conversion ratio(FCR)=feed intake/weight gain of fish body.

[0200] (3) Test Results

[0201] It can be seen from the test results shown in Table 8 that the use of the aspartic acid derivatives in feeds for aquatic products had an effect of improving the production performance of grass carps, which was reflected by the increases in the weight gain and the improvement in the feed conversion ratio. The weight gain of each test group was improved, wherein the weight gains of the test groups fed with N-glycyl-DL-aspartic acid and diethyl N-carbamoyl-DL-aspartate had a significant improvement effect compared with the control group. Compared with the control group, the feed conversion ratios of the test groups were all significantly declined, which improved the utilization of feeds.

TABLE-US-00008 TABLE 8 Test results of use of aspartic acid derivatives in feeds for aquatic products Average Average initial final Weight weight (g) weight (g) gain (%) (FCR) Group 425.2 ± 4.8 757.0 ± 3.5.sup.a  78.02 ± 1.20.sup.a 1.749 ± 0.008.sup.a I Group 423.0 ± 5.5 774.5 ± 4.8.sup.b .sup. 83.19 ± 1.41.sup.b 1.650 ± 0.011.sup.b II Group 431.0 ± 5.9 778.2 ± 4.3.sup.b 80.62 ± 1.46 1.671 ± 0.008.sup.b III Group 432.5 ± 6.1 781.8 ± 4.4.sup.b 80.76 ± 1.52 1.662 ± 0.008.sup.b IV Group 430.2 ± 4.6 781.0 ± 5.1.sup.b 81.58 ± 0.96 1.653 ± 0.009.sup.b V Group 422.0 ± 5.0  769.2 ± 4.5.sup.ab 82.32 ± 1.24 1.671 ± 0.008.sup.b VI Group 420.2 ± 6.8 772.0 ± 6.3.sup.b .sup. 83.74 ± 1.53.sup.b 1.650 ± 0.008.sup.b VII Note: Data in the same column labeled with different letters indicates a significant difference (P < 0.05).

[0202] The above-mentioned embodiments only describe several implementations of the present invention, and there are other ways to implement the present invention. Correspondingly, the embodiments of the present invention are described as examples, but they should not be interpreted as limiting the patent scope of the present invention, and the present invention also encompasses modifications made within the scope of the present invention and based on the same inventive concept or equivalent contents added in the claims.