Calcium formate and calcium carbonate compound feed additive as well as preparation method and application thereof

Abstract

The invention discloses a calcium formate and calcium carbonate compound feed additive as well as a preparation method and application thereof. Based on the total mass of the additive, the total mass content of calcium formate and calcium carbonate is not lower than 97%, and the balance is trace water and inevitable trace impurities. The mass of the calcium carbonate is 12%-16% of the mass of the calcium formate; the preparation method comprises the following steps: adding a certain amount of formic acid into a reaction tank; starting stirring, adding calcium carbonate into the formic acid, keeping the formic acid to be excessive, and fully reacting for 2-3 hours; adding excessive calcium hydroxide, and continuously reacting for 2-3 hours; putting the reaction liquid into a liquid storage tray, and standing until the reaction liquid is completely solidified; crushing and drying the solid product under carbon dioxide low-temperature airflow; and sieving the dried product to obtain the calcium formate and calcium carbonate compound feed additive. The feed additive disclosed by the invention is slowly dissolved in water, can effectively improve the palatability, and slowly releases formic acid in animal digestive tracts to achieve the effects of continuously inhibiting bacteria and promoting calcium absorption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of feed additives, in particular to a calcium formate and calcium carbonate composite feed additive and a preparation method and application thereof. BACKGROUND

[0002] Organic acids and their salts as feed acidifiers have the effects of reducing the pH value of the gastrointestinal tract, inhibiting the reproduction of harmful bacteria, improving the digestion and absorption rate of nutrients, etc., and have no residues and are not easy to produce drug resistance, so they are widely used in livestock breeding. Calcium formate has become one of the mainstream products due to its relatively low price and obvious acidification effect.

[0003] However, the commonly used calcium formate has obvious defects: its water solubility is too strong, it is quickly dissolved and releases formate ions in the oral cavity and the front part of the gastrointestinal tract, which on the one hand produces a bitter taste, affecting the palatability and feed intake of animals; on the other hand, it leads to the rapid consumption of acidification in the front part of the gastrointestinal tract, which cannot effectively act on the rear part of the intestinal tract, limiting the maximum exertion of its bacteriostatic and growth-promoting effects. Therefore, it is of great practical significance to develop a calcium formate product that can slowly release in the digestive tract, has good palatability, and has more persistent bacteriostatic effect. SUMMARY

[0004] The purpose of the present application is to provide a calcium formate and calcium carbonate composite feed additive and a preparation method and application thereof. The feed additive of the present application slowly dissolves in water, can effectively improve the palatability, and slowly releases formic acid in the digestive tract of animals, thereby achieving the effects of sustained bacteriostasis and promoting calcium absorption.

[0005] The technical solution of the present application is a calcium formate and calcium carbonate composite feed additive, wherein the total mass content of calcium formate and calcium carbonate is not less than 97% based on the total mass of the additive, and the balance is trace moisture and unavoidable trace impurities; the mass of the calcium carbonate is 12% to 16% of the mass of the calcium formate.

[0006] The calcium formate and calcium carbonate composite feed additive described above, wherein the mass of the calcium carbonate is 13% to 15% of the mass of the calcium formate.

[0007] The calcium formate and calcium carbonate composite feed additive described above, wherein the mass of the calcium carbonate is 14% of the mass of the calcium formate.

[0008] The preparation method of the calcium formate and calcium carbonate composite feed additive described above, comprising the following steps: Step 1: adding a certain amount of formic acid into a reaction tank; Step 2: starting stirring, adding calcium carbonate into the formic acid, keeping the formic acid in excess, and fully reacting for 2 to 3 hours; Step 3: adding excess calcium hydroxide and continuously reacting for 2 to 3 hours; Step 4, place the reaction solution into a liquid reservoir, stand until completely solidified; Step 5, crush and dry the solid product under the low-temperature carbon dioxide gas flow; Step 6, after sieving the dried product, obtain the calcium formate and calcium carbonate compound feed additive.

[0009] In the aforementioned preparation method, in step 1, the mass concentration of the formic acid is 75-85%; in step 2, the calcium carbonate is light calcium carbonate with a mass concentration greater than 95%, and the calcium carbonate feeding amount is 80-90% of the mass of the formic acid; in step 3, the purity of the calcium hydroxide is greater than 95%, and the feeding amount is 25-35% of the mass of the formic acid.

[0010] In the aforementioned preparation method, the feeding mass ratio of the formic acid, the calcium carbonate and the calcium hydroxide is 100:85:30.

[0011] In the aforementioned preparation method, in step 5, the crushing particle size is less than 0.18 mm, the carbon dioxide gas flow temperature is 60-80 DEG C, and the gas flow speed is 3-4 m / s.

[0012] An application of the aforementioned calcium formate and calcium carbonate compound feed additive in preparing livestock and poultry feed.

[0013] In the aforementioned application, the calcium formate and calcium carbonate compound feed additive is applied in the livestock and poultry feed at an addition amount of 0.5%-2.5% of the total mass of the feed.

[0014] Compared with the prior art, the present application has the following remarkable beneficial effects: 1. The feed additive slowly dissolves in water, avoids the bitter taste caused by the rapid dissolution of calcium formate in the oral cavity and the front part of the gastrointestinal tract of animals, effectively improves the palatability of animals, and increases the feed intake of livestock and poultry; at the same time, formic acid can be slowly released in the digestive tract of animals, the acidification effect can cover the rear part of the intestinal tract, realize sustained bacteriostasis, maximize the bacteriostatic and growth-promoting effects of calcium formate, and further improve the intestinal digestion and absorption capacity by slowly adjusting the intestinal pH value to create a suitable environment for the reproduction of intestinal beneficial bacteria.

[0015] 2. The total mass content of calcium formate and calcium carbonate in the feed additive is not less than 97%, both of which can provide calcium nutrients for livestock and poultry, and the compound formed by the two can effectively promote the absorption and utilization of calcium by animals; at the same time, the presence of calcium carbonate gives the additive good acid-base buffering effect, can stabilize the intestinal acid-base environment, reduce intestinal stress, and has the dual effects of acidification and bacteriostasis and calcium nutrition supplementation, helping the development of livestock and poultry bones and the health of the body.

[0016] 3、The preparation method of the application does not generate waste water in the whole process, meets the production requirements of green environmental protection, has mild reaction conditions, only needs steps of conventional stirring, reaction, standing, crushing, drying and the like, is simple and easy to operate, and has clear raw material feeding ratio, controllable reaction parameters, and the like, so that the composite additive meeting the quality requirements can be stably prepared, and the low-cost and large-scale industrial production can be realized; meanwhile, the crushing and drying are completed under the low-temperature carbon dioxide gas flow, so that the product property change can be effectively avoided, and the quality stability of the composite additive is ensured.

[0017] 4、The feed additive of the application can be added into the livestock and poultry feed, so that the livestock and poultry production performance can be significantly improved, the daily weight gain and egg production rate of the livestock and poultry such as laying hens and piglets can be improved, the feed-egg ratio and feed-weight ratio can be reduced, the feed conversion efficiency can be improved, the livestock and poultry diarrhea rate can be effectively reduced, and the breeding loss can be reduced; meanwhile, the livestock and poultry product quality can be improved, for example, the eggshell thickness and eggshell strength of the eggs are improved, the egg quality is improved, the additive has no residue in the livestock and poultry body, and the harmful bacteria are not easy to produce drug resistance, so that the development requirements of green breeding are met, and the application value is high. DETAILED DESCRIPTION

[0018] The application will be further described below in combination with examples, but the examples are not used as the basis for limiting the application.

[0019] Example 1: A calcium formate and calcium carbonate composite feed additive and a preparation method thereof I. Formula composition of the composite feed additive The calcium formate and calcium carbonate composite feed additive (hereinafter referred to as the composite additive) of the example takes calcium formate as the main component, and takes calcium carbonate as the composite component, and the total mass content of the calcium formate and the calcium carbonate is greater than or equal to 97% based on the total mass of the additive, and the balance is trace water and trace impurities inevitably generated in the preparation process, and no other artificial additive component is added.

[0020] The mass ratio of the calcium carbonate to the calcium formate is a core control index, the basic ratio is that the mass of the calcium carbonate is 12% to 16% of the mass of the calcium formate, the preferred ratio is that the mass of the calcium carbonate is 13% to 15% of the mass of the calcium formate, and the best ratio is that the mass of the calcium carbonate is 14% of the mass of the calcium formate, and under this ratio, the slow-dissolving property, the acid-base buffering capacity and the application effect of the additive are optimal.

[0021] II. Technical indexes of the preparation raw materials The raw materials for preparing the composite additive are formic acid, light calcium carbonate and calcium hydroxide, and the purity, concentration and the like of each raw material need to meet the following requirements, so as to ensure the reaction sufficiency and the product quality stability: The formic acid has a mass concentration of 75% to 85%, provides formate ions for the reaction, and is a core raw material for generating calcium formate; Light calcium carbonate: mass concentration > 95%, particle size < 0.08mm, avoid coarse particle size to affect the reaction contact area, ensure sufficient reaction with formic acid; Calcium hydroxide: purity > 95%, particle size < 0.08mm, ensure the reaction efficiency with the remaining formic acid, and the subsequent reaction with carbon dioxide to generate calcium carbonate, adjust the product ratio.

[0022] The raw material feeding mass ratio is the core process parameter, the basic feeding ratio is formic acid: calcium carbonate: calcium hydroxide = 100: (80-90): (25-35) (pure mass); the best feeding ratio is 100:85:30, under this ratio, the mass ratio of calcium carbonate to calcium formate in the product after reaction is stable at about 14%, and the total content of the two is ≥97%.

[0023] III. Detailed preparation process steps The preparation process of the composite additive of the application includes four stages of raw material reaction, product solidification, crushing and drying, and screening finished product, no wastewater is generated throughout the process, the reaction conditions are mild, and no special high-pressure and high-temperature equipment is needed, the specific operation steps are as follows: Step 1: raw material feeding A certain amount of formic acid (mass concentration 75%-85%) is added to a closed reaction tank, the amount of formic acid added can be adjusted according to actual production needs, and in industrial production, 100kg-1000kg of formic acid solution equivalent to pure formic acid can be added by batch.

[0024] Step 2: reaction of formic acid and calcium carbonate The stirring device of the reaction tank is started, and uniform stirring is maintained, light calcium carbonate is slowly added to the formic acid, the amount of calcium carbonate added is 80%-90% (optimum 85%) of the pure mass of formic acid, the formic acid is kept in excess throughout the process to avoid the influence of residual calcium carbonate which is not completely reacted on the product quality; after adding, continue to stir for 2-3 hours to make the formic acid and calcium carbonate fully react to generate calcium formate and carbon dioxide, the reaction equation is: 2HCOOH + CaCO3 = Ca (HCOO)2 + CO2↑ + H2O.

[0025] Step 3: reaction of formic acid and calcium hydroxide After the calcium carbonate reaction is completed, calcium hydroxide is added to the reaction solution, the amount of calcium hydroxide added is 25%-35% (optimum 30%) of the pure mass of formic acid, after adding, continue to stir for 2-3 hours to make the calcium hydroxide and the remaining formic acid fully react to generate calcium formate, the reaction equation is: ; a small amount of calcium hydroxide is kept in the reaction solution in the later stage of the reaction to provide raw material for the subsequent generation of calcium carbonate.

[0026] Step 4: product standing and solidification The reaction liquid completing the two-step reaction is transferred to a closed liquid storage tray (depth less than 10 cm), and is naturally placed without additional temperature control. After the reaction liquid is completely solidified into a solid block, it enters the subsequent crushing and drying process. The solidification process can fully mix calcium formate and unreacted calcium hydroxide, ensuring uniform composition of the subsequent product.

[0027] Step 5: Crushing and drying under low-temperature carbon dioxide gas flow The solid product in the liquid storage tray is transferred to a crushing and drying integrated machine, and crushing and drying operations are simultaneously performed under a low-temperature carbon dioxide gas flow environment. The core process parameters need to be strictly controlled. The crushing particle size is controlled to be less than 0.18 mm (80 mesh) to ensure the fineness of the additive and facilitate uniform mixing in the subsequent feed. The carbon dioxide gas flow temperature is 60-80°C, and the gas flow speed is 3-4 m / s. The low-temperature gas flow can avoid the thermal decomposition of calcium formate, and the remaining calcium hydroxide can fully react with carbon dioxide to generate calcium carbonate, so that the calcium formate and calcium carbonate in the product reach the designed ratio. The reaction equation is: Ca(OH)2 + CO2 = CaCO3 + H2O.

[0028] Step 6: Screening of finished product The product after crushing and drying is screened through a standard screen with a mesh size matching the crushing particle size (≤0.18 mm) to remove a small amount of coarse particle impurities. The screened powder is the finished calcium formate and calcium carbonate compound feed additive, with a total content of calcium formate and calcium carbonate ≥97% and a calcium carbonate mass being 12%-16% of the mass of calcium formate.

[0029] Example 2: This example verifies the effect of raw material feeding mass ratio on the components in the product The raw material feeding amounts of six parallel reaction groups are designed, and the pure mass is shown in Table 1.

[0030] Table 1 Raw materials / kg T01 T02 T03 T04 T05 T06 Formic acid 100 100 100 100 100 100 Calcium carbonate 80 80 85 85 85 90 Calcium hydroxide 20 24 28 32 34 32 Formic acid was added to the reaction pool, stirring was started, and calcium carbonate was added. The reaction was continued for 3.0 hours. Calcium hydroxide was added, and the reaction was continued for 2.5 hours. The reaction liquid was placed in a liquid storage tray and left to solidify completely. The solid product was crushed and dried under low-temperature carbon dioxide gas flow. After screening the dried product, a calcium formate and calcium carbonate compound was obtained.

[0031] Samples T01-T6 were taken, and the contents of calcium formate and calcium carbonate were determined. The content of calcium formate was determined according to GB7300.806. The content of calcium carbonate was determined by weight method. An appropriate amount of sample was taken, 200-300 times of pure water was added, and the sample was stirred and dissolved. The precipitate was obtained by filtration, dried, and weighed to calculate the content of calcium carbonate in the sample. The test results are shown in Table 2.

[0032] Table 2 Index / % T01 T02 T03 T04 T05 T06 Water 1.4 0.8 0.4 0.5 1.2 0.9 Calcium formate 84.3 85.1 85.7 85.4 82.3 83.1 Calcium carbonate 7.5 11.9 12.1 12.3 10.5 13.2 Calcium formate + calcium carbonate 91.8 97.0 97.8 97.7 92.8 96.3 Calcium carbonate / calcium formate 8.9 14.0 14.1 14.4 12.8 15.9 The results of Table 2 show that the product of the six test groups, calculated by the mass of the fed formic acid, the calcium formate concentration in the products of T02-T04 groups is higher, and the mass ratio of calcium carbonate / calcium formate is stable at 14.0-14.4%, the total mass of calcium formate and calcium carbonate is greater than 97%, which meets the requirements.

[0033] Further, 1.000 g of calcium formate (T0 group, analytical pure reagent) and 1.000 g of each of the six product samples in Example 2 (T01-T06) were accurately weighed, diluted with purified water to 500 ml, magnetically stirred at a speed of 250 rpm, and the solution pH was measured at 30, 40, and 60 min, respectively. The results are shown in Table 3.

[0034] Table 3 Time / min T0 T01 T02 T03 T04 T05 T06 30 8.6 8.1 7.8 7.1 7.3 8.3 7.4 60 8.5 8.5 8.5 7.4 7.6 8.8 9.2 90 8.5 12.6 9.1 8.2 8.4 13.1 12.0 The results of Table 3 show that pure calcium formate in T0 group is easily soluble in water, and the pH after dissolution is 8.5. The pH of T02-T04 groups slowly rises with time. The pH of T01, T05, and T06 groups exceeds 12.0 at 90 min, indicating that the product still contains a small amount of calcium hydroxide. It can be seen that the products of T03 and T04 groups have good slow dissolution characteristics. This indicates that the reaction is fully prepared during the preparation process, and the final product does not contain calcium hydroxide.

[0035] Example 3: This example is to verify the effect of the compound feed additive on the production performance of laying hens The test feed was prepared. See Table 4: Item t0 t1 t2 t3 Ingredients / kg / / / / Corn 640 637 638 637 Soybean meal 240 240 240 240 Layer premix 50 50 50 50 Stone powder 70 53 62 53 Calcium formate 0 20 0 0 Compound feed additive 0 0 10 20 Total 1000 1000 1000 1000 Nutritional index / % / / / / Crude protein 15.7 15.6 15.5 15.4 Metabolic energy 12.2 12.2 12.2 12.2 Calcium 3.6 3.6 3.6 3.6 Total phosphorus 0.45 0.45 0.45 0.45 Available phosphorus 0.29 0.29 0.29 0.29 Lysine 0.85 0.85 0.85 0.85 Methionine 0.32 0.32 0.32 0.32 In Table 4, t0 group is the basic feed of laying hens without acidifier. t1 group adds feed-grade calcium formate with purity > 95%. t2 and t3 groups add compound feed additives. The metabolic energy, crude protein, calcium, phosphorus, and other nutritional values of the four feeds are basically the same.

[0036] The feeding test design: single factor design, i.e. one control group and three test groups. The number of laying hens in each group is 960, the test chickens are 50 weeks old, and the laying rate is 92-93%. The test has a pre-test period of 1 week and a formal test period of 5 weeks. The test laying hens in each group are raised in the same closed laying hen house, and the light, ventilation, and other conditions are automatically controlled. Three-layer full ladder type cages are used. The internal environmental conditions of the chicken house where the test chickens are located are basically the same. Artificial feeding is carried out twice a day, and egg collection is carried out once a day. The fixed feeding amount is 120-122 g per day, which is adjusted in combination with real-time feed intake, laying rate, air temperature, and other factors.

[0037] The weekly feed amount, egg number, broken egg number, egg weight, and dead and culled number were recorded in groups. Before the end of the experiment, 30 sample eggs were randomly collected from each group for 3 consecutive days to measure egg quality indicators such as eggshell thickness. The above egg production performance and egg quality indicators were used to evaluate the efficacy of the experimental feed. The egg production performance results are shown in Table 5.

[0038] Table 5 Item n t0 t1 t2 t3 P-value 52-week body weight / g 30 1920±130 1877±141 1889±137 1926±142 0.447 Egg laying rate / % 5 91.5 ± 0.7 b ]] 92.8 ± 0.9 a ]] 93.4 ± 1.0 a ]] 93.9 ± 0.8 a ]] 0.003 Egg weight / g 5 61.4 ± 0.3 c ]] 61.9 ± 0.3 ab ]] 62.1 ± 0.4 a ]] 61.5 ± 0.3 bc ]] 0.012 Daily egg production / g 5 56.2 ± 0.5 b ]] 57.4 ± 0.6 a ]] 58.0 ± 0.4 a ]] 57.7 ± 0.5 a ]] 0.000 Feed to egg ratio 5 2.17 ± 0.02 a ]] 2.13 ± 0.01 b ]] 2.10 ± 0.02 c ]] 2.11 ± 0.02 bc ]] 0.000 Note: The same row data is marked with different letters, which represents a significant difference between groups (p<0.05), and the following table is the same.

[0039] As can be seen from Table 5, the addition of calcium formate and different concentrations of compound feed additives can improve egg production performance and feed conversion efficiency. The egg production rate and daily egg production indicators are the highest in the t3 group, which is 2.6% and 3.2% higher than those in the t0 group, respectively, with a very significant difference (p<0.01). The feed-to-egg ratio in the t3 group is 3.3% and 1.43% lower than that in the t0 group and the t1 group, respectively, with a very significant difference (p<0.01). The egg production performance of the t3 group is better than that of the t1 group, but the difference is not significant (p>0.05).

[0040] The egg quality results are shown in Table 6.

[0041] Table 6 Item n t0 t1 t2 t3 P-value Egg weight / g 30 61.8±3.3 62.1±2.4 62.2±3.1 61.7±3.2 0.906 Haff unit / HU 30 77.4±4.3 78.8±3.2 77.9±3.7 78.2±2.9 0.492 Shell thickness / mm 30 0.32 ± 0.03 b ]] 0.34 ± 0.02 a ]] 0.34 ± 0.03 a ]] 0.33 ± 0.02 ab ]] 0.007 Shell strength / kgf 30 4.37 ± 0.31 b ]] 4.58 ± 0.29 a ]] 4.52 ± 0.39 ab ]] 4.66 ± 0.41 a ]] 0.016 Table 6 As can be seen from Table 6, the addition of calcium formate and different concentrations of compound feed additives can improve eggshell thickness and strength, with a significant difference (p<0.05), and there is no significant difference between the t1-t3 groups. Conclusion: The addition of calcium formate and different concentrations of compound feed additives can significantly improve the production performance and egg quality of laying hens. The performance of the group with 1.0% calcium formate compound is the best, and there is no significant difference between the groups with 2.0% calcium formate and calcium formate compound.

[0042] Example 4: This example is to verify the effect of compound feed additive on the production performance of weaned piglets Feed design: The basic feed for weaned piglets is composed of 55% corn, 15% soybean meal, and 30% piglet concentrated feed. The feed has a digestible energy DE of more than 14.2 Mcal / kg, a crude protein of more than 18.8%, a lysine of more than 1.4%, a total phosphorus of more than 0.55%, and a calcium of more than 0.45%. The concentrated feed does not contain organic acid additives. The t0 group of pigs consumes the basic feed, and the t01, t02, and t03 groups add 2.0% calcium formate, 1.5% compound feed additive, and 2.0% compound feed additive, respectively.

[0043] Experimental animals and design: 240 piglets of 30±3 days old, uniform weight and condition. Single factor design, 240 piglets were randomly divided into 4 groups, 3 replicates in each group, 20 piglets in each replicate. Each replicate was single-housed, 4 groups were fed with 4 kinds of feed, free access to feed. Pre-test period of 7 days, the test period of 30 days. In the unit of replicate, the first day and the last day of the test period were weighed in the morning, the daily feed intake was recorded, and the number of diarrhea piglets in each group was recorded every day. Table 7 shows the effect of compound feed additive on the growth performance of piglets.

[0044] Table 7 Item / kg n t0 t1 t2 t3 P-v a lue]]> Initial weight 3 7.53±0.18 7.61±0.22 7.43±0.19 7.58±0.20 0.708 Final weight 3 19.32 ± 0.61 b ]] 20.66 ± 0.55 a ]] 21.44 ± 0.63 a ]] 21.53 ± 0.60 a ]] 0.007 Daily weight gain 3 0.39±0.01c 0.44 ± 0.02 b ]] 0.47 ± 0.01 a ]] 0.47 ± 0.02 a ]] 0.001 Feed intake 3 0.72 ± 0.02 b ]] 0.75 ± 0.03 b ]] 0.81 ± 0.04 a ]] 0.82 ± 0.03 a ]] 0.011 Feed to weight ratio 3 1.85 ± 0.06 a ]] 1.70 ± 0.05 b ]] 1.72 ± 0.04 b ]] 1.74 ± 0.06 b ]] 0.034 Diarrhea head count 1800 137 a ]] 105 b ]] 107 b ]] 95 b ]] 0.024 As can be seen from Table 7, the daily gain, feed intake and feed conversion rate of the three test groups with the addition of compound feed additive are better than those of the control group, and the difference is significant (p<0.05). The daily gain index of t2 and t3 groups is increased by 6.8% (p<0.05) compared with t1 group and by 20.5% (p<0.01) compared with t0 group. The feed intake index of t2 and t3 groups is increased by 8.0% (p<0.01) compared with t1 group and by 13.9% (p<0.01) compared with t0 group. There is no significant difference (p>0.05) among the three test groups in terms of feed conversion rate and diarrhea rate, which are lower than those of t0 group (p<0.05). Therefore, the three test groups with the addition of acidifier can significantly improve the daily gain of piglets and reduce the feed conversion rate and diarrhea rate. The addition of 1.5% and 2.0% calcium formate compound is better than that of 2.0% calcium formate in improving the feed intake and growth performance of piglets, and the performance of the group with 1.5% calcium formate compound is the most obvious. Therefore, the three test groups with the addition of compound feed additive can significantly improve the daily gain of piglets and reduce the feed conversion rate and diarrhea rate. The addition of 1.5% and 2.0% compound feed additive is better than that of 2.0% calcium formate in improving the feed intake and growth performance of piglets, and the performance of the group with 1.5% calcium formate compound is the most obvious.

[0045] The above examples fully prove the effectiveness and superiority of the calcium formate and calcium carbonate compound feed additive provided by the present application, the preparation method and application thereof. The present application is not limited to the above embodiments, and any modification made on the basis of the concept of the present application shall be included in the protection scope of the present application.

Claims

1. A compound feed additive of calcium formate and calcium carbonate, characterized in that, Based on the total mass of the additives, the total mass content of calcium formate and calcium carbonate is not less than 97%, with the remainder being trace amounts of moisture and unavoidable trace impurities; the mass of the calcium carbonate is 12% to 16% of the mass of the calcium formate.

2. The calcium formate and calcium carbonate compound feed additive according to claim 1, characterized in that, The mass of the calcium carbonate is 13% to 15% of the mass of the calcium formate.

3. The calcium formate and calcium carbonate compound feed additive according to claim 2, characterized in that, The mass of the calcium carbonate is 14% of the mass of the calcium formate.

4. The method for preparing the calcium formate and calcium carbonate compound feed additive according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Add a certain amount of formic acid to the reaction tank; Step 2: Turn on the stirrer, add calcium carbonate to the formic acid, keep the formic acid in excess, and allow it to react fully for 2-3 hours. Step 3: Add excess calcium hydroxide and continue the reaction for 2-3 hours; Step 4: Place the reaction solution into a storage pan and let it stand until it completely solidifies; Step 5: Crush and dry the solid product under a low-temperature carbon dioxide gas flow; Step 6: After sieving the dried product, a compound feed additive of calcium formate and calcium carbonate is obtained.

5. The preparation method according to claim 4, characterized in that, In step 1, the mass concentration of formic acid is 75-85%; in step 2, the calcium carbonate is light calcium carbonate with a mass concentration greater than 95%, and the amount of calcium carbonate fed is 80-90% of the mass of formic acid; in step 3, the purity of calcium hydroxide is greater than 95%, and the amount fed is 25-35% of the mass of formic acid.

6. The preparation method according to claim 5, characterized in that, The mass ratio of formic acid, calcium carbonate, and calcium hydroxide is 100:85:

30.

7. The preparation method according to claim 5, characterized in that, In step 5, the particle size is less than 0.18 mm, the carbon dioxide gas temperature is 60-80℃, and the gas velocity is 3-4 m / s.

8. The application of a calcium formate and calcium carbonate compound feed additive as described in any one of claims 1-3 in the preparation of livestock and poultry feed.

9. The application according to claim 8, characterized in that: The calcium formate and calcium carbonate compound feed additive is applied to livestock and poultry feed at an addition rate of 0.5% to 2.5% of the total feed mass.