Pig feed based on pineapple peel fermentation and preparation method thereof

Abstract

The present application relates to fermentation engineering, more particularly to the field of fermentation livestock feed, and particularly to a pig feed based on pineapple peel fermentation and a preparation method thereof. The pig feed is prepared by using rice root mold, Candida utilis and Lactobacillus plantarum as fermentation strains through segmented fermentation with pineapple peel as raw material. The pig feed can be used as a raw material for feeding lactating sows, which can reduce the feeding cost while ensuring the nutritional health of sows, and is also beneficial to increase the deposition of pork flavor substances, improve meat quality, reduce the ammonia nitrogen content in the air of the pig house and in the pig manure, and reduce the odor of the pig house.

Description

Technical Field

[0001] This invention relates to fermentation engineering, and more specifically to the field of fermented livestock feed, particularly a pig feed based on pineapple peel fermentation and its preparation method. Background Technology

[0002] The nutritional needs of pigs vary significantly at different growth stages. For example, piglets require a high-protein, low-fiber diet to promote intestinal development; finishing pigs prioritize energy density; and breeding sows require precise control of calcium, phosphorus, and fiber levels to maintain reproductive performance. Lactating sows, due to their high milk production load, require further enhancement of calcium and phosphorus intake and optimization of fiber function. Traditional feeds mainly rely on the addition of inorganic salts to supplement calcium and phosphorus content, which leads to poor palatability, reduced absorption rates, and consequently, postpartum paralysis and decreased milk quality.

[0003] Silage is a feed made from green plants through lactic acid bacteria fermentation. It retains more than 80% of vitamins, degrades fiber, and inhibits pathogens. For lactating sows, feeding silage has advantages such as alleviating heat stress, improving intestinal health, and reducing feed costs. However, silage is deficient in natural calcium and phosphorus, especially after fermentation, which leads to even greater calcium loss. Furthermore, anti-nutritional factors such as phytic acid further reduce phosphorus bioavailability. This can lead to hypocalcemia in sows with long-term silage feeding, increasing the rate of postpartum paralysis and reducing the calcium content in sow's milk. Piglets fed with sow's milk are highly susceptible to rickets, which in turn reduces the sow's fertility. Therefore, improving the calcium and phosphorus content of silage has always been a key research challenge in livestock feed.

[0004] Pineapple is a nutritious fruit, with its flesh being edible and its peel inedible. According to research, the proportions of water, citric acid, and total sugar in pineapple peel are similar to those in the flesh, while its crude protein and ash content are more than twice that of the flesh, making it an excellent silage feed ingredient. Chinese patent publication CN115669812A, entitled "A Fermented Premix for Piglets," discloses a piglet feed obtained from fermented pineapple waste. Chinese patent publication CN106721078A, entitled "A Method for Producing Silage," also discloses a silage feed made from fermented pineapple peel. This shows that pineapple peel fermentation as silage has been used for some time. However, compared to other silage materials, pineapple peel has an average calcium content but a much lower phosphorus content. Silage obtained from fermented pineapple peel still suffers from low calcium and phosphorus content, making it unsuitable for feeding lactating sows. Summary of the Invention

[0005] The specific information of the fermentation strains used in this invention is as follows:

[0006] Rhizopus oryzae was purchased from the Guangdong Provincial Center for Microbial Culture Collection, with the accession number GDMCC NO.3.126.

[0007] Candida utilis was purchased from Guangdong Provincial Microbial Culture Collection Center, with accession number GDMCC NO.2.9.

[0008] Lactiplantibacillus plantarum was purchased from the Guangdong Provincial Center for Microbial Culture Collection, with the accession number GDMCC NO.1.140.

[0009] Levilactobacillus brevis was purchased from the Guangdong Provincial Center for Microbial Culture Collection, with the accession number GDMCC NO.1.773.

[0010] Lactobacillus delbrueckii subsp. lactis was purchased from Guangdong Provincial Center for Microbial Culture Collection, with accession number GDMCC NO.1.3694.

[0011] The purpose of this invention is to provide a pig feed based on pineapple peel fermentation and its preparation method. It has the characteristics of high crude protein content, low crude fiber rate, and high calcium and phosphorus content. It can effectively improve the milk fat rate of sow milk, and also help to increase the deposition of pork flavor substances, improve meat quality, reduce the ammonia nitrogen content in the air and pig manure in pig houses, and reduce the odor in pig houses. It can be applied in the field of livestock feed.

[0012] In view of this, on the one hand, the present invention provides a method for preparing feed based on pineapple peel fermentation, including material pretreatment, feeding and fermentation steps. The feeding step involves adding pineapple peel, fermentation liquid, water and pH buffer to a fermentation container. The fermentation liquid contains at least Rhizopus oryzae, Candida utilis and Lactobacillus plantarum. The pH buffer includes calcium dihydrogen phosphate and calcium carbonate. The fermentation step involves first performing aerobic fermentation and then anaerobic fermentation.

[0013] This invention employs a segmented fermentation method for pineapple peel. The first stage is aerobic fermentation, primarily driven by *Rhizopus oryzae* and *Candida utilis*. However, because *Rhizopus oryzae* produces lactic acid during fermentation, a pH buffer neutralizes this lactic acid, maintaining a stable pH level. As aerobic fermentation progresses, lactic acid gradually accumulates. At this point, the pH buffer is completely consumed and converted into easily absorbed soluble lactate, effectively increasing the calcium and phosphorus content of the finished feed. As lactic acid accumulates, the pH level gradually decreases. At this stage, the fermentation tank vents are closed, transitioning to anaerobic fermentation. The remaining oxygen in the fermentation tank is gradually consumed, inhibiting *Rhizopus oryzae* activity and causing *Candida utilis* to transition from aerobic to anaerobic fermentation, continuously consuming oxygen. Once all oxygen in the fermentation tank is depleted, *Candida utilis* activity decreases, and the pH level drops to the optimal pH for *Lactobacillus plantarum*. *Lactobacillus plantarum* then enters an active phase, performing the final anaerobic fermentation of the material to obtain well-fermented silage. The silage processed through the above fermentation process has the characteristics of high crude protein content, low crude fiber content, and high calcium and phosphorus content. When fed to sows, the milk fat content of sows' milk is significantly improved.

[0014] Material pretreatment is a conventional method in the production of silage, including but not limited to pretreating pineapple peels and preparing fermentation broth. Pretreating pineapple peels refers to processing fresh pineapple peels to a suitable fermentation state, including homogenizing the size of the peels, controlling their moisture content, and sterilization. Cutting is the simplest and most common method for homogenizing the size of fresh pineapple peels; therefore, fresh pineapple peels can be cut. The moisture content of fresh pineapple peels determines the fermentation effect; too much or too little moisture will affect the fermentation. Therefore, excessively wet fresh pineapple peels need to be dried to improve the subsequent fermentation effect, but they should not be allowed to dry out completely. Strict microbial control is required for pineapple peel fermentation; therefore, sterilization is also a viable method. Sterilizing fresh pineapple peels before fermentation can effectively reduce contamination by other microorganisms and improve fermentation efficiency. The above methods are not absolute; those skilled in the art can process pineapple peels using conventional techniques to achieve the same desired effect.

[0015] The methods for preparing fermentation broth are also conventional in this field. For example, after inoculating the fermentation bacteria onto a solid culture medium and culturing it for a period of time, it is inoculated into a liquid culture medium for expansion culture. Some fermentation bacteria can be directly washed with sterile water to obtain spore suspension.

[0016] In the segmented fermentation process of this invention, controlling the pH value of the fermentation system is the most critical technical point. Excessive addition of pH buffer prolongs the aerobic fermentation stage, while insufficient addition fails to effectively supplement the calcium and phosphorus content of the silage. Therefore, in some embodiments, the molar ratio of calcium dihydrogen phosphate to calcium carbonate in the pH buffer is (2.5–3):1, and the amount of pH buffer added accounts for 0.12%–0.15% of the total weight of the fermentation system.

[0017] The type and molar ratio of pH buffers are also key to controlling the pH stability of the fermentation system. Therefore, in some embodiments, the molar ratio of calcium dihydrogen phosphate to calcium carbonate in the pH buffer is 3:1.

[0018] The duration of aerobic fermentation is related to the amount of pH buffer consumed; the longer the aerobic fermentation, the greater the amount of pH buffer consumed. The duration of aerobic fermentation can be adjusted according to the amount of pH buffer added. Aerobic fermentation can be stopped and anaerobic fermentation can begin when the pH value of the fermentation system begins to decrease significantly. Therefore, in some embodiments, the aerobic fermentation duration is 18–28 hours, and the temperature is controlled at 28°C–32°C; the anaerobic fermentation duration is not less than 48 hours, and the temperature is controlled at 37°C–40°C. In some embodiments, the amount of pH buffer added accounts for 0.15% of the total weight of the fermentation system. In some embodiments, the aerobic fermentation duration is 24 hours.

[0019] In some embodiments, the concentration ratio of Rhizopus oryzae, Candida utilis, and Lactobacillus plantarum in the fermentation broth is 6:4:5.

[0020] The concentration ratio of Rhizopus oryzae, Candida utilis, and Lactobacillus plantarum has a significant impact on the crude protein content of silage. After extensive creative work, the inventors of this invention discovered that the highest crude protein content in silage is achieved when the concentration ratio of Rhizopus oryzae, Candida utilis, and Lactobacillus plantarum is 6:4:5.

[0021] In some embodiments, the weight ratio of the pineapple peel to the water is 3:7. In some embodiments, the thickness of the pineapple peel layer in the fermentation tank is 5 cm.

[0022] On the other hand, the present invention provides a feed prepared by the above-described preparation method.

[0023] In some implementations, the above-mentioned feed is used to feed lactating sows, which can effectively increase the sows' active feeding rate, improve feed palatability, and significantly increase the milk fat content of sows' milk, thereby ensuring the nutritional health of piglets.

[0024] In some embodiments, the above-mentioned feed, when used to feed sows, can increase the milk fat percentage of sow's milk, provide precursors for muscle fat deposition, effectively increase the deposition of pork flavor substances, improve meat quality, reduce the ammonia nitrogen content in the air and manure of pigsties, and reduce the odor of pigsties.

[0025] The present invention has the following advantages and effects:

[0026] 1. This invention utilizes the control of pH value and oxygen content to achieve segmented fermentation, and obtains a pig feed with high crude protein content and low crude fiber rate after fermenting pineapple peel.

[0027] 2. The pig feed prepared by the method of the present invention improves the deficiency of low calcium and phosphorus content, overcomes the problem of postpartum paralysis in lactating sows due to long-term consumption, reduces the risk of rickets in piglets, and improves the breeding quality of pigs.

[0028] 3. The pig feed of the present invention can effectively increase the milk fat content of lactating sows' milk, ensuring the nutritional health of piglets. Detailed Implementation

[0029] The pig feed of this invention belongs to the field of fermentation engineering. To make the objectives, features, and advantages of this invention more apparent and understandable, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] Unless otherwise specified, all experimental reagents and materials used in this invention are commercially available.

[0031] Example 1

[0032] A type of pig feed is prepared through the following steps:

[0033] S1. Chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside; mix calcium dihydrogen phosphate and calcium carbonate evenly in a molar ratio of 3:1 to obtain a calcium dihydrogen phosphate-calcium carbonate mixture, and set aside.

[0034] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶. 8 Prepare a suspension of *Lactobacillus plantarum* cells / mL for later use;

[0035] S3. Put 29.955 parts by weight of sterilized pineapple peel into the fermentation tank, add 69.895 parts by weight of sterile water, and then add 0.15 parts by weight of calcium dihydrogen phosphate-calcium carbonate mixture. Stir evenly and compact to make the material layer thickness 5cm.

[0036] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus plantarum suspension.

[0037] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 28 hours.

[0038] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0039] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0040] Example 2

[0041] A type of pig feed is prepared through the following steps:

[0042] S1. Chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside; mix calcium dihydrogen phosphate and calcium carbonate evenly at a molar ratio of 2.5:1 to obtain a calcium dihydrogen phosphate-calcium carbonate mixture, and set aside.

[0043] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶. 8 Prepare a suspension of *Lactobacillus plantarum* cells / mL for later use;

[0044] S3. Put 29.955 parts by weight of sterilized pineapple peel into the fermentation tank, add 69.895 parts by weight of sterile water, and then add 0.15 parts by weight of calcium dihydrogen phosphate-calcium carbonate mixture. Stir evenly and compact to make the material layer thickness 5cm.

[0045] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus plantarum suspension.

[0046] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 24 hours.

[0047] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0048] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0049] Example 3

[0050] A type of pig feed is prepared through the following steps:

[0051] S1. Chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside; mix calcium dihydrogen phosphate and calcium carbonate evenly in a molar ratio of 3:1 to obtain a calcium dihydrogen phosphate-calcium carbonate mixture, and set aside.

[0052] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶. 8 Prepare a suspension of *Lactobacillus plantarum* cells / mL for later use;

[0053] S3. Put 29.964 parts by weight of sterilized pineapple peel into the fermentation tank, add 69.916 parts by weight of sterile water, then add 0.12 parts by weight of calcium dihydrogen phosphate-calcium carbonate mixture, stir evenly, and compact to make the material layer thickness 5cm.

[0054] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus plantarum suspension.

[0055] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 18 hours.

[0056] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0057] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0058] Comparative Example 1

[0059] A type of pig feed is prepared through the following steps:

[0060] S1. Finely chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside.

[0061] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶.8 Prepare a suspension of *Lactobacillus plantarum* cells / mL for later use;

[0062] S3. Put 30 parts by weight of sterilized pineapple peel into the fermentation tank, add 70 parts by weight of sterile water, stir evenly, and compact to make the material layer thickness 5cm.

[0063] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus plantarum suspension.

[0064] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 24 hours.

[0065] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0066] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0067] Comparative Example 2

[0068] A type of pig feed is prepared through the following steps:

[0069] S1. Finely chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside.

[0070] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 Prepare a suspension of *Candida utilis* cells / mL for later use;

[0071] S3. Put 30 parts by weight of sterilized pineapple peel into the fermentation tank, add 70 parts by weight of sterile water, stir evenly, and compact to make the material layer thickness 5cm.

[0072] S4. Inoculate the fermenter with 1.2% (v / v) Rhizopus oryzae spore suspension and 0.8% (v / v) Candida utilis suspension;

[0073] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 72 hours.

[0074] S6. Dry the material, mix it evenly, and package it to obtain pig feed.

[0075] Comparative Example 3

[0076] A type of pig feed is prepared through the following steps:

[0077] S1. Chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside; mix calcium dihydrogen phosphate and calcium carbonate evenly in a molar ratio of 3:1 to obtain a calcium dihydrogen phosphate-calcium carbonate mixture, and set aside.

[0078] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶. 8 Prepare a suspension of Lactobacillus brevis bacteria per mL for later use;

[0079] S3. Put 29.955 parts by weight of sterilized pineapple peel into the fermentation tank, add 69.895 parts by weight of sterile water, and then add 0.15 parts by weight of calcium dihydrogen phosphate-calcium carbonate mixture. Stir evenly and compact to make the material layer thickness 5cm.

[0080] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus brevis suspension.

[0081] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 28 hours.

[0082] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0083] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0084] Comparative Example 4

[0085] A type of pig feed is prepared through the following steps:

[0086] S1. Chop fresh pineapple peel, dry it until the moisture content is about 30%, sterilize it, and set aside; mix calcium dihydrogen phosphate and calcium carbonate evenly in a molar ratio of 3:1 to obtain a calcium dihydrogen phosphate-calcium carbonate mixture, and set aside.

[0087] S2, Preparation concentration is 1×10 8 A suspension of Rhizopus oryzae spores per mL, with a concentration of 1×10⁻⁶. 8 A suspension of *Candida utilis* cells / mL at a concentration of 1×10⁻⁶. 8 A suspension of *Lactobacillus delbrueckii* subsp. *lactamella* cells / mL was prepared for later use.

[0088] S3. Put 29.955 parts by weight of sterilized pineapple peel into the fermentation tank, add 69.895 parts by weight of sterile water, and then add 0.15 parts by weight of calcium dihydrogen phosphate-calcium carbonate mixture. Stir evenly and compact to make the material layer thickness 5cm.

[0089] S4. Inoculate the fermenter with 0.8% (v / v) Rhizopus oryzae spore suspension, 0.53% (v / v) Candida utilis suspension and 0.67% (v / v) Lactobacillus delbrueckii subsp. lactis suspension;

[0090] S5. Sterile air is introduced into the fermenter at a rate of 15L / min. The temperature inside the fermenter is controlled at 32℃, and aerobic fermentation is carried out for 28 hours.

[0091] S6. Close the vent of the fermenter and control the temperature inside the fermenter at 37℃ for anaerobic fermentation for 48 hours;

[0092] S7. Dry the material, mix it evenly, and package it to obtain pig feed.

[0093] Test Example 1: Crude Protein Determination

[0094] Crude protein content of pig feeds from Examples 1-3 and Comparative Examples 1-2 was determined according to GB / T 5009.5-2016.

[0095] Accurately weigh 1.0000 g of sample, add 100 mL of distilled water and wash thoroughly to dissolve and remove inorganic nitrogen. Then filter with quantitative filter paper, dry the filter paper and residue at 60 °C, and place them in a Kjeldahl flask. Determine the crude protein content of each sample using the semi-micro Kjeldahl nitrogen determination method. The results are shown in Table 1.

[0096] Table 1 Crude Protein Content

[0097] Example 1 21.33 Example 2 20.87 Example 3 20.15 Comparative Example 1 14.66 Comparative Example 2 18.52 Comparative Example 3 17.33 Comparative Example 4 18.56

[0098] The results show that the crude protein content of the pig feeds prepared in Examples 1, 2, and 3 is all higher than 20%, while the crude protein content of the pig feeds prepared in Comparative Examples 1 and 2 is less than 20%. This demonstrates that the addition of a pH buffer promotes fermentation and the production of crude protein, thereby improving the nutritional value of the feed. Furthermore, Comparative Example 1, which did not add a pH buffer but still used a staged fermentation method, actually had a lower crude protein content than the pig feed prepared in Comparative Example 2. This proves that the pH buffer is crucial for staged fermentation; without a pH buffer, staged fermentation not only fails to increase crude protein content but may also inhibit the normal fermentation process. Furthermore, the lactic acid bacteria used in Example 1 were replaced in Comparative Examples 3 and 4. Although the same segmented fermentation process was used, the crude protein content of the pig feed prepared in Comparative Examples 3 and 4 was not significantly increased compared with Comparative Example 2. This proves that there is a synergistic effect among Rhizopus oryzae, Candida utilis and Lactobacillus plantarum. The co-fermentation can significantly increase the crude protein content of silage.

[0099] Test Example 2: Determination of Crude Fiber Content

[0100] The crude fiber content of pig feed from Examples 1-3 and Comparative Examples 1-2, as well as fresh pineapple peel, was determined according to the filter crucible method in GB / T 6434-2022. The results are shown in Table 2.

[0101] Table 2 Crude fiber content

[0102] Example 1 2.7 Example 2 2.8 Example 3 2.9 Comparative Example 1 22.7 Comparative Example 2 3.3 Comparative Example 3 3.1 Comparative Example 4 3.2 Fresh pineapple peel 26.9

[0103] The results show that, compared with fresh pineapple peel, the crude fiber content in the pig feed prepared in Examples 1, 2, 3 and Comparative Example 2 was significantly reduced. However, the crude fiber content in the pig feed prepared in Comparative Example 1 was not significantly reduced. This further proves that pH buffer is the key to staged fermentation. In the absence of pH buffer, staged fermentation may inhibit the normal fermentation process.

[0104] Test Example 3: Determination of Calcium and Phosphorus Content

[0105] The calcium and phosphorus contents in pig feed of Examples 1-3 and Comparative Examples 1-2, as well as fresh pineapple peel, were determined.

[0106] Calcium and phosphorus standard solutions were prepared, and the absorbance of the standard solutions was measured using atomic absorption spectrometry to plot a standard curve. 0.500 g of sample was accurately weighed, washed thoroughly with 100 mL of distilled water, filtered, and the absorbance of the filtrate was measured using atomic absorption spectrometry. Based on the standard curve, the calcium and phosphorus contents of each sample were calculated. The results are shown in Table 3.

[0107] Table 3 Calcium and phosphorus content of each sample

[0108] Example 1 606 334 Example 2 721 236 Example 3 675 277 Comparative Example 1 107 38 Comparative Example 2 126 44 Fresh pineapple peel 212 64

[0109] The results showed that, compared to fresh pineapple peels, Comparative Examples 1 and 2, which did not contain a pH buffer, exhibited a significant decrease in calcium and phosphorus content after fermentation. Examples 1, 2, and 3, which added a pH adjuster containing calcium and phosphorus during fermentation, significantly increased the calcium and phosphorus content in the final pig feed products.

[0110] Test Example 4: Sow Milk Fat Percentage Test

[0111] Thirty healthy lactating sows within 5 days of lactation were randomly divided into 5 groups of 6 sows each. Fresh sow milk was collected from all sows, and the milk fat percentage was measured using a FOSS MilkoScan milk composition analyzer and recorded. Each group was fed the pig feeds specified in Examples 1, 2, 3, Comparative Examples 1, and 2 four times daily for 14 consecutive days, with normal access to water. After 14 days, fresh sow milk was collected from all sows, and the milk fat percentage was measured using a FOSS MilkoScan milk composition analyzer and recorded. The average milk fat percentage for each group and the rate of change in milk fat percentage over 14 days were calculated. The results are shown in Table 4.

[0112] Table 4. Milk fat percentage and 14-day change rate in sows

[0113]

[0114] The fat percentage of sow's milk increases with the age of lactating sows, reaching its peak around 20 days of lactation. This test used 5-day-old sows; theoretically, after 14 days, the fat percentage of their secreted sow's milk should show a significant increase compared to before the test. However, the results showed that if sows were fed only the pig feed of Comparative Examples 1 and 2, the fat percentage of their sow's milk did not increase significantly after 14 days, and even decreased, proving that the lactation capacity of sows fed only ordinary silage declined severely. Sows fed the pig feed of Examples 1, 2, and 3 all showed a significant increase in milk fat percentage, proving that lactating sows can meet their nutritional needs during lactation by feeding only the pig feed of this invention.

[0115] Test Example 5: Daily Weight Gain Test of Piglets

[0116] Ten healthy sows awaiting farrowing were randomly divided into two groups of five: an experimental group and a control group. All sows had normal food and water intake before farrowing. After farrowing, the piglets were marked and weighed, and their birth weight was recorded. Furthermore, the sows' feed formula was changed after farrowing; the formula is shown in Table 5.

[0117] Table 5 Feed Formulation

[0118]

[0119] Postpartum sows were fed according to the formula in Table 5, with normal drinking water and normal milk supply. The health status of the piglets was observed daily, and any piglets with abnormal conditions (including those that did not survive, contracted diseases, or had indigestion) were recorded. After weaning, the piglets were weighed and their weaning weight was recorded. After excluding data from piglets that exhibited abnormalities during lactation, the daily gain (ADG) of the piglets was calculated. The calculation formula is as follows, and the results are shown in Table 6:

[0120]

[0121] Table 6 Piglet Indicators

[0122] ADG(g) 237.6±22.7 204.3±26.9 Survival rate (%) 97.37 91.89

[0123] The results showed that the ADG of the experimental group piglets was significantly higher than that of the control group piglets, and the survival rate of the experimental group piglets was significantly higher than that of the control group piglets. This proves that the experimental group sows have better nursing ability than the control group sows. Feeding the silage of Example 1 of this invention can effectively improve the nursing ability of sows, thereby improving the survival rate and weight gain of piglets.

[0124] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0125] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0126] The present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing feed based on pineapple peel fermentation, comprising the steps of material pretreatment, feeding, and fermentation, characterized in that, The feeding step involves adding pineapple peel, fermentation broth, water, and a pH buffer to the fermentation container. The fermentation broth contains Rhizopus oryzae, Candida utilis, and Lactobacillus plantarum, with a concentration ratio of 6:4:

5. The pH buffer consists of calcium dihydrogen phosphate and calcium carbonate, and its addition amount is 0.12% to 0.15% of the total weight of the fermentation system. The fermentation process involves first performing aerobic fermentation for 18-28 hours, followed by anaerobic fermentation for 48 hours. The molar ratio of calcium dihydrogen phosphate to calcium carbonate in the pH buffer is (2.5~3):1; The temperature for aerobic fermentation is controlled at 28℃~32℃; the temperature for anaerobic fermentation is controlled at 37℃~40℃.

2. The preparation method according to claim 1, characterized in that, The pH buffer contains calcium dihydrogen phosphate and calcium carbonate in a molar ratio of 3:

1.

3. The preparation method according to claim 2, characterized in that, The amount of pH buffer added accounts for 0.15% of the total weight of the fermentation system.

4. The preparation method according to claim 1, characterized in that, The weight ratio of the pineapple peel to the water is 3:

7.

5. The preparation method according to claim 1, characterized in that, The aerobic fermentation process lasts for 24 hours.

6. The feed prepared by the method according to any one of claims 1-5.

7. The feed according to claim 6, characterized in that, Used for feeding lactating sows.

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