Preparation method of livestock feed based on lignin-based composite calcium

Abstract

The application discloses a kind of preparation method of poultry feed based on lignin-based composite calcium.The method first introduces carboxyl group by oxidizing treatment to alkali lignin or lignin sulfonate, and complexation or crosslinking occurs with soluble calcium source under suitable pH conditions, and lignin-based composite calcium powder with particle size D50 of 10-70 μm and calcium mass fraction of 8-25 wt% is obtained by spray drying.Subsequently, grain raw materials, protein raw materials, oil, amino acids, vitamins and trace elements are mixed according to the formula proportion, the composite calcium powder is added to the basic mixture at 0.5-8.0 wt%, and the granular feed suitable for poultry feeding is prepared by steam conditioning and granulation cooling process at 65-85℃.The prepared granular feed has the advantages of improved granular durability index and reduced pulverization rate, and can be used as an effective calcium source for meat poultry, egg poultry, pigs and ruminants, which is beneficial to improve the quality of feed and increase the utilization efficiency of calcium.

Description

Technical Field

[0001] This invention relates to a method for preparing poultry and livestock feed, specifically a method for preparing poultry and livestock feed based on lignin-based complex calcium. Background Technology

[0002] A stable and effective calcium supply is essential for the growth and development of poultry and livestock, bone formation, and the maintenance of egg quality. Insufficient calcium absorption, low calcium source utilization, and mismatched calcium release at different stages of digestion are significant causes of skeletal abnormalities, decreased eggshell quality, and fluctuations in production performance. Therefore, improving the digestibility and absorption efficiency of dietary calcium has become an urgent problem to be solved in the livestock industry.

[0003] Currently, feed commonly uses inorganic calcium sources such as calcium carbonate and limestone powder. However, these have low solubility and limited bioavailability, easily dissolving rapidly in large quantities in the stomach, while the available calcium in the small intestine is insufficient, making it difficult to meet the continuous calcium requirements of poultry and livestock. Furthermore, inorganic calcium sources have poor dispersibility in feed systems; high addition levels affect the uniformity of the diet and easily reduce the actual absorption rate of calcium. Meanwhile, feed pelleting requires a certain level of pellet durability, and existing inorganic calcium sources cannot simultaneously provide both calcium supplementation and improved pellet structure. Traditional calcium supplementation methods often rely on large amounts of inorganic calcium sources and require the additional use of binders such as starch and cellulose to improve pellet strength, increasing the complexity of the feed system and hindering green, low-carbon production. Industrial byproduct lignin has a stable structure, is widely available, and contains active groups such as carboxyl and phenolic hydroxyl groups that can bind to metal ions. It also possesses natural binding properties, making it a biomass material with potential nutritional and structural regulation advantages, but it has not yet been fully utilized in feed.

[0004] Therefore, developing a novel lignin-based composite calcium that combines lignin with a soluble calcium source and applying it to feed preparation can improve calcium utilization while enhancing particle structure, thereby realizing the high-value utilization of lignin. This is of great significance for improving feed quality and promoting green farming.

[0005] Compared to directly adding calcium lignin sulfonate (which is essentially a simple combination system of lignin sulfonate and free calcium ions) to feed, the oxidized and activated lignin-based complex calcium described in this invention has the following advantages: (1) More stable complex structure: Oxidized lignin contains a higher content of carboxyl and phenolic hydroxyl groups, which can form a multi-point coordination structure with calcium ions, making it difficult for calcium to be released under the high temperature conditions of feed pelleting, thus solving the problem of easy dissociation of calcium ions in calcium lignin sulfonate. (2) Superior calcium sustained-release performance: Lignin-based complex calcium is not easily dissolved all at once in the stomach, which can increase the amount of calcium available in the small intestine and improve the apparent digestibility of calcium by 10–20%; (3) Significantly improved pellet formability: Oxidized lignin has better binding and film-forming properties, and can coat the surface of feed pellets during pelleting, thus significantly improving the pellet durability index (PDI). (4) Avoid absorption antagonism caused by adding "lignin + calcium source" separately: When lignin and calcium source are added separately, the two are not fully combined, and calcium ions are easily combined with phytic acid or dietary anions, reducing bioavailability; while the composite calcium of the present invention avoids this problem with a stable complex structure. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing poultry and livestock feed based on lignin-based composite calcium. The method is simple, green and environmentally friendly, and the calcium source in the feed has good dispersibility and stability, which can improve the utilization efficiency of calcium and improve the physical quality of feed particles, thereby achieving the dual functions of nutritional calcium supplementation and particle structure enhancement.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] This invention discloses a method for preparing poultry and livestock feed based on lignin-based calcium complex, comprising the following steps: (1) Take alkali lignin or lignin sulfonate from herbaceous or woody sources, disperse it in deionized water at 5-15 wt%, and stir at 200-400 rpm for 10-20 min at room temperature to obtain a lignin dispersion; add an oxidant to the system so that the mass ratio of oxidant to lignin is 3-12:100, and react at 40-70℃ for 1-2 h to oxidize the aromatic structure of lignin and introduce carboxyl groups; then adjust the pH of the oxidizing solution to 6-9, add a calcium source, so that calcium ions complex or crosslink with the carboxyl groups and phenolic hydroxyl groups of activated lignin, and react at 300-600 rpm for 0.5-2 h to form a composite calcium precursor; spray dry the obtained precursor (inlet 150-190℃, outlet 70-90℃) to obtain lignin-based composite calcium powder with a median particle size D50 of 10-70 μm and a calcium mass fraction of 8-25 wt%; (2) Weigh the grain raw materials, protein raw materials, oils, amino acids, vitamins and trace elements premix according to the formula ratio, and mix them in a horizontal or vertical mixer at a speed of 400-800 rpm for 2-6 minutes to obtain the basic feed mixture A; (3) Slowly add the lignin-based complex calcium powder obtained in step (1) to the basic feed mixture A in step (2) so that the amount of lignin-based complex calcium added to the feed is 0.5 to 8.0 wt%, and mix at 400 to 600 rpm for 3 to 8 minutes to obtain feed mixture B containing lignin-based complex calcium; (4) The lignin-based composite calcium feed mixture B from step (3) is transported to a conditioner and conditioned with steam at a temperature of 65-85°C for 15-60 s to adjust the moisture content of the material to 14-18 wt% to obtain conditioned material. The conditioned material is then processed into pellet feed through a ring die pellet mill with a pellet diameter of 2.0-4.0 mm and a length of 6-14 mm. After cooling to 25-35°C, poultry and livestock pellet feed based on lignin-based composite calcium is obtained.

[0009] In step (1) of this invention, the lignin raw material is alkali lignin or lignin sulfonate from herbaceous or woody sources; the oxidant is sodium persulfate, ammonium persulfate, potassium persulfate, or hydrogen peroxide; the carboxyl content of the lignin after oxidation treatment is 0.5–2.5 mmol / g; the calcium source is one or more of calcium chloride, calcium lactate, or calcium acetate; the particle size distribution of the lignin-based composite calcium powder satisfies D10 of 3–20 μm, D90 of 80–150 μm, and a relative standard deviation (RSD) of less than 30%.

[0010] In step (2) of the present invention, the formula ratio is 40-70 wt% of grain raw materials, 15-35 wt% of protein raw materials, and 2-5 wt% of oil.

[0011] In step (2) of the present invention, the oil includes one or more of soybean oil, soybean lecithin oil or fish oil; the premix contains a variety of vitamins (A, D3, E, etc.) and trace elements (copper sulfate, ferrous sulfate, zinc sulfate, manganese sulfate, etc.) required by poultry and livestock; other raw materials include conventional additives such as limestone powder, choline chloride, lysine, methionine, phytase, and salt.

[0012] In step (4) of the present invention, the pellet durability index (PDI) of the prepared pellet feed is 3-15% higher than that of the control feed without added lignin-based calcium compound, and the pulverization rate is reduced by 10-30%.

[0013] In step (4) of the present invention, the lignin-based calcium-based pelleted feed is used for feeding poultry, laying hens, pigs and ruminants.

[0014] This invention involves oxidizing and activating lignin to introduce carboxyl and phenolic hydroxyl groups, which can form complexes or cross-links with calcium ions. The resulting lignin-based composite calcium powder is then reacted with a soluble calcium source. The obtained composite calcium powder is added to a basic feed formulation and processed into pelleted feed through conditioning and pelleting processes. This ensures that the composite calcium is uniformly dispersed in the feed system and has a more stable structure, thereby improving calcium utilization efficiency and pelleted feed quality.

[0015] The lignin-based composite calcium material used in this invention possesses multiple functional groups, the ability to complex with metals, and resistance to rapid and complete dissolution in the stomach, resulting in a more suitable release behavior of calcium in the gastrointestinal environment. Through the combined action of lignin and the calcium source, the controllable release of the calcium source in the stomach can be improved, increasing the amount of available calcium in the small intestine and thus enhancing overall calcium absorption efficiency. Developing novel composite calcium sources utilizing the coordination properties of lignin is an important approach to improving dietary calcium utilization efficiency, reducing the amount of traditional inorganic calcium sources, and maintaining feed nutritional stability.

[0016] Lignin is a widely available natural aromatic polymer material with good biocompatibility, natural binding properties, and strong structural stability. After oxidation and activation, lignin can provide coordinating groups to bind with calcium ions, thereby forming a stable complex calcium structure. This invention utilizes these properties of lignin to enable the complex calcium to function as both a calcium source and an auxiliary binding component during feed pelleting, improving pellet durability and reducing pulverization rate, thus playing a vital role in both feed processing and nutrition.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention uses the method of combining oxidative activated lignin with soluble calcium source to prepare lignin-based composite calcium, and applies it to feed preparation. This method can improve the stability and dispersibility of calcium source in feed, and improve its release characteristics in the digestive tract. The preparation process is simple, green and environmentally friendly, and meets the requirements of sustainable development of modern feed industry.

[0019] (2) The pelleted feed prepared by the method of the present invention has good calcium utilization efficiency and physical structure stability, which can improve pellet durability, reduce pulverization rate, and reduce the amount of traditional inorganic calcium source and additional binder, thereby improving feed quality and reducing the negative impact on diet composition.

[0020] (3) Compared with commercially available calcium lignosulfonate and other traditional calcium sources, this invention introduces a high density of carboxyl and phenolic hydroxyl groups onto the lignin skeleton through oxidation treatment, enabling calcium ions to bind to lignin through a more stable multi-site complex / cross-linked structure, rather than simple ionic bonding. This deep complex structure not only makes the calcium mass fraction of the composite calcium controllable (up to 25 wt%), but also endows it with excellent staged release behavior in the gastrointestinal tract, effectively avoiding the instantaneous and rapid dissolution of calcium ions and significantly improving bioavailability; at the same time, oxidation activation significantly enhances the natural binding properties of lignin, resulting in a better effect on improving particle strength at the same addition amount. Detailed Implementation

[0021] The following embodiments are provided to better illustrate the present invention, but the scope of protection of the present invention is not limited to the following examples. Example 1

[0022] Alkali lignin from herbal sources was dispersed in deionized water at 10 wt% and stirred at 300 rpm for 15 min at room temperature to obtain a lignin dispersion. Sodium persulfate at a mass ratio of 8:100 was added to the system, and the reaction was carried out at 60 °C for 1.5 h to partially oxidize the lignin and introduce carboxyl groups. The pH of the system was then adjusted to 7.5, and calcium lactate solution was added to induce a complexation reaction between calcium ions and lignin. The reaction was carried out at 400 rpm for 1 h to obtain a lignin-based calcium composite precursor. The precursor was spray-dried (inlet temperature 170 °C, outlet temperature 80 °C) to obtain a lignin-based calcium composite powder with a median particle size D50 of 32 μm and a calcium content of 16 wt%.

[0023] Prepare the basic feed according to the following formula: 58 wt% corn, 26 wt% soybean meal, 3 wt% oil, 4 wt% premix, and 9 wt% other ingredients. Mix the basic feed in a horizontal mixer at 500 rpm for 4 min to obtain a mixture. Add 2 wt% lignin-based calcium compound powder to the mixture and mix at 450 rpm for 5 min to ensure thorough dispersion of the calcium compound.

[0024] The oil used is soybean oil; the premix is ​​a poultry and livestock-specific premix containing vitamins A, D3, and E, as well as trace elements such as copper sulfate and ferrous sulfate; other ingredients include salt, dicalcium phosphate, and lysine. The resulting compound calcium feed mixture is fed into a conditioner and conditioned with steam at 75°C for 30 seconds to achieve a moisture content of 16 wt%. It is then pelleted using a 3 mm diameter ring die pellet mill and cooled to 28°C to obtain the finished product.

[0025] Test results show that, compared with the control feed without added compound calcium, the pellet durability index (PDI) of the feed of the present invention is increased by 9.6%, the pulverization rate is reduced by 22.3%, and the apparent digestibility of calcium in the diet is increased by 12.4%, which has significant advantages.

[0026] The Particle Durability Index (PDI) test method is based on ASAE S269.4 standard: Take 500 g of pelleted feed W0; Place it in the PDI test tube and roll it at 50 rpm for 10 minutes; The rolled sample was then passed through a 2.8 mm sieve. Measure the weight W1 of the material on the sieve; Calculate: PDI(%) = (W1 / W0) × 100%.

[0027] Powdering rate test method: Weigh 1000 g of sample; Use a vibrating sieve with a sieve aperture of 2.36 mm to sieve for 1 min; The mass W of the section passing through is obtained. p ; Calculation: Powdering rate (%) = (W p / 1000)×100%.

[0028] Methods for testing apparent calcium digestibility (AIA endogenous indicator method): Animals were allowed to acclimatize for 5 days before formal sampling was performed 3 days later. Collect fecal samples, dry and pulverize them; Determine the calcium content and acid-insoluble ash (AIA) content in feed and feces; Calculate: Ca (消化率) =1-(AIA) (d) / AIA (f) )×(Ca (f) / Ca (d) ); AIA (d) AIA (f) The AIA content in feed and feces, respectively, and the Ca content are as follows: (d) Ca (f) These are the calcium contents of feed and feces, respectively. Example 2

[0029] Alkali lignin from herbal sources was dispersed at 10 wt% in deionized water and stirred at 300 rpm for 15 min at room temperature to obtain a lignin dispersion. Sodium persulfate, an oxidant, was added to the system to achieve an oxidant-to-lignin mass ratio of 8:100. The reaction was carried out at 60 °C for 1.5 h, resulting in the oxidation of some aromatic structures and the introduction of carboxyl groups. The pH of the oxidation solution was adjusted to 7.0, and calcium lactate solution was added to complex calcium ions with lignin. The mixture was stirred at 400 rpm for 1 h to obtain a composite calcium precursor. The precursor was spray-dried (inlet temperature 170 °C, outlet temperature 80 °C) to obtain a lignin-based composite calcium powder with a median particle size D50 of 35 μm and a calcium mass fraction of 15 wt%.

[0030] Weigh out 60 wt% of grains, 25 wt% of soybean meal, 3 wt% of oil, and 2 wt% of amino acid and vitamin mineral premix, and mix for 3 min to obtain a basic mixture. Add compound calcium powder at a ratio of 2.0 wt% of feed mass to the basic mixture, and mix at 500 rpm for 5 min to obtain a feed mixture containing compound calcium.

[0031] The mixture was steam-conditioned at 75°C for 30 seconds, resulting in a moisture content of 16 wt%. It was then pelleted into 3.0 mm diameter pellets using a ring die pellet mill and cooled to 28°C to obtain the feed product. The pellet durability index (PDI) was measured to be 93.2%, and the pulverization rate was 4.3%, showing significant improvement compared to the control feed without added calcium (PDI = 86.5%, pulverization rate = 9.8%). Even after changes in the lignin and calcium source types, the feed maintained good pellet structure stability and calcium dispersibility, indicating that the method of this invention is applicable to various lignin and calcium source systems.

[0032] In this embodiment, the determination of PDI, powdering rate and apparent calcium digestibility were all performed according to the method described in Example 1. Example 3

[0033] Alkali lignin from herbal sources was dispersed at 10 wt% in deionized water and stirred at 300 rpm for 15 min at room temperature to obtain a lignin dispersion. Hydrogen peroxide was added to the system to make the mass ratio of lignin to lignin 10:100, and the reaction was carried out at 60 °C for 1.5 h to partially oxidize the lignin to generate carboxyl groups. The pH of the reaction solution was adjusted to 8, and then calcium lactate solution was added to allow calcium ions to complex with the carboxyl and phenolic hydroxyl groups in the activated lignin. The reaction was carried out at 500 rpm for 1 h to obtain a composite calcium precursor. The obtained precursor was spray-dried (inlet temperature 180 °C, outlet temperature 85 °C) to obtain lignin-based composite calcium powder with a median particle size D50 of 45 μm and a calcium mass fraction of 22 wt%.

[0034] Weigh out 60wt% corn flour, 25wt% soybean meal, 3wt% vegetable oil and 2wt% trace element mineral premix according to the formula ratio, and mix them in a horizontal mixer at 600 rpm for 4 min to obtain the basic feed mixture.

[0035] The lignin-based composite calcium powder obtained in step (1) is slowly added to the basic feed mixture at 8 wt%, and mixed at 500 rpm for 5 min to make the composite calcium evenly distributed, thus obtaining the lignin-based composite calcium feed mixture.

[0036] The above feed mixture was conveyed to a conditioner and conditioned with steam at 80°C for 40 seconds to bring the moisture content of the material to 16 wt%, thus obtaining the conditioned material. Subsequently, it was pelleted using a ring die pellet mill (ring die aperture 3 mm), with the pellet length controlled to 10 mm. After being cooled to 28°C by a counter-current cooler, lignin-based composite calcium poultry and livestock pellet feed was obtained.

[0037] Performance test results showed that the pellet durability index (PDI) of this pelleted feed was 94.2%, which was 12.8% higher than that of the control feed without lignin-based calcium complex (PDI=83.5%); the pulverization rate decreased from 9.6% in the control group to 5.1%. After 21 days of feeding, the calcium content in the tibia of broilers increased by 9.3% compared with the control group, and the serum total calcium concentration increased by 7.8%, indicating that the lignin-based calcium complex achieved a more balanced two-stage calcium release in the digestive tract (rapid release in the stomach and slow release in the small intestine / cecum), while the binding effect of the lignin skeleton significantly improved the stability of the pellet structure.

[0038] In this embodiment, the determination of PDI, powdering rate and apparent calcium digestibility were all performed according to the method described in Example 1. Comparative Example 1 (Lignin and Calcium Source Physical Mixture Control Group)

[0039] The basic feed was prepared according to the same matrix formulation as in Example 1: 58 wt% corn, 26 wt% soybean meal, 3 wt% oil, 4 wt% premix, and 9 wt% other raw materials. Instead of adding the lignin-based composite calcium powder of this invention, 1.68 wt% unactivated herbal-derived alkali lignin and 0.32 wt% calcium lactate (total weight 2.0 wt%, consistent with the total addition amount in Example 1) were directly added externally, according to the effective component ratio of the composite calcium in Example 1. The mixing, conditioning, granulation, and cooling processes were exactly the same as in Example 1. Comparative Example 2 (Commercial Calcium Lignosulfonate Control Group)

[0040] The basic feed was prepared using the same matrix formulation as in Example 1. 2.0 wt% of commercially available industrial-grade calcium lignin sulfonate was added directly to it. The mixing, conditioning, pelleting, and cooling processes were exactly the same as in Example 1. Effect comparison experiment

[0041] The performance indicators of the pelleted feeds prepared in Example 1, Comparative Example 1, and Comparative Example 2 were determined using the testing method described in Example 1. The test results are as follows: Example 1: Pellet durability index (PDI) was 93.5%, pulverization rate was 4.1%, and apparent calcium digestibility was 81.2%; Comparative Example 1: Pellet durability index (PDI) was 85.2%, pulverization rate was 10.4%, and apparent calcium digestibility was 68.8%; Comparative Example 2: Pellet durability index (PDI) was 87.1%, pulverization rate was 8.9%, and apparent calcium digestibility was 71.5%.

[0042] As can be seen from the above data, Example 1, which incorporates the lignin-based composite calcium of the present invention, exhibits significantly better PDI and apparent calcium digestibility than the physical mixing group (Comparative Example 1) and the commercial lignin sulfonate group (Comparative Example 2), with a substantial reduction in pulverization rate. This strongly demonstrates that the deep multi-site complex / crosslinked structure formed by lignin and calcium ions after oxidative activation not only endows the material with stronger engineering adhesion but also achieves a superior sustained-release composite effect in the digestive tract of poultry and livestock, demonstrating significant technical advantages.

Claims

1. A method for preparing poultry and livestock feed based on lignin-based calcium composites, characterized in that, The following steps are included: (1) Take alkali lignin or lignin sulfonate from herbaceous or woody sources, disperse it in deionized water at 5-15 wt%, and stir at 200-400 rpm for 10-20 min at room temperature to obtain a lignin dispersion; add an oxidant to the system so that the mass ratio of oxidant to lignin is 3-12:100, and react at 40-70 ℃ for 1-2 h to oxidize the aromatic structure of lignin and introduce carboxyl groups; then adjust the pH of the oxidation solution to 6-9, add a calcium source, so that calcium ions complex or crosslink with the carboxyl groups and phenolic hydroxyl groups of activated lignin, and react at 300-600 rpm for 0.5-2 h to form a composite calcium precursor; spray dry the obtained precursor (inlet 150-190 ℃, outlet 70-90 ℃) to obtain lignin-based composite calcium powder with a median particle size D50 of 10-70 μm and a calcium mass fraction of 8-25 wt%; (2) Weigh the grain raw materials, protein raw materials, oils, amino acids, vitamins, trace elements and other raw material premixes according to the formula ratio, and mix them in a horizontal or vertical mixer at a speed of 400-800 rpm for 2-6 minutes to obtain the basic feed mixture; (3) Slowly add the lignin-based complex calcium powder obtained in step (1) to the basic feed mixture in step (2) so that the amount of lignin-based complex calcium added to the feed is 0.5 to 8.0 wt%, and mix at 400 to 600 rpm for 3 to 8 minutes to obtain a feed mixture containing lignin-based complex calcium. (4) The feed mixture containing lignin-based complex calcium obtained in step (3) is transported to a conditioner and conditioned with steam at a temperature of 65-85 °C for 15-60 s to adjust the moisture content of the material to 14-18 wt% to obtain conditioned material; the conditioned material is then processed into pellet feed by a ring die pellet mill with a pellet diameter of 2.0-4.0 mm and a length of 6-14 mm, and cooled to 25-35 °C to obtain poultry and livestock pellet feed based on lignin-based complex calcium.

2. The method for preparing poultry and livestock feed based on lignin-based complex calcium according to claim 1, characterized in that, In step (1), the lignin raw material is alkali lignin or lignin sulfonate from herbaceous or woody sources; the oxidant is sodium persulfate, ammonium persulfate, potassium persulfate, or hydrogen peroxide; the carboxyl content of the lignin after oxidation treatment is 0.5–2.5 mmol / g; the calcium source is one or more of calcium chloride, calcium lactate, or calcium acetate; the particle size distribution of the lignin-based composite calcium powder satisfies D10 of 3–20 μm, D90 of 80–150 μm, and a relative standard deviation (RSD) of less than 30%.

3. The method for preparing poultry and livestock feed based on lignin-based complex calcium according to claim 1, characterized in that, In step (2), the formula ratio is 40-70 wt% of grain raw materials, 15-35 wt% of protein raw materials, and 2-5 wt% of oil.

4. The method for preparing poultry and livestock feed based on lignin-based complex calcium according to claim 1, characterized in that, In step (2), the oil includes one or more of soybean oil, soybean lecithin oil or fish oil; the premix contains a variety of vitamins (A, D3, E, etc.) and trace elements (copper sulfate, ferrous sulfate, zinc sulfate, manganese sulfate, etc.) required by poultry and livestock; other raw materials include conventional additives such as limestone powder, choline chloride, lysine, methionine, phytase, and salt.

5. The method for preparing poultry and livestock feed based on lignin-based complex calcium according to claim 1, characterized in that, In step (4), the lignin-based calcium-based pelleted feed is used for feeding poultry, laying hens, pigs and ruminants.