Low-protein daily ration composition for growing pigs as well as preparation method and application of low-protein daily ration composition

Abstract

The invention provides a low-protein daily ration composition for growing pigs. The low-protein daily ration composition is prepared from the following raw materials in parts by weight: 65.0 to 75.0 parts of corn, 10.0 to 15.0 parts of wheat bran, 5.0 to 10.0 parts of corn protein powder, 1.0 to 2.0 parts of soybean oil, 0.5 to 1.0 part of sodium chloride, 0.5 to 1.5 parts of mountain flour, 1.0 to 1.5 parts of calcium hydrophosphate, 0.1 to 1.0 part of lysine hydrochloride, 0.1 to 0.5 part of threonine, 0.02 to 0.5 part of tryptophan, 0.25 to 0.5 part of slow-release lysine hydrochloride, 0.03 to 0.12 part of slow-release threonine and 1.0 part of premix. Based on the combination effect of various sustained-release amino acids, the release rate of the sustained-release amino acids is optimized, so that the sustained-release amino acids are complementary with the amino acid release dynamic state of the corn protein powder, and the growth performance of growing pigs and the feed utilization rate are remarkably improved. According to the scheme, nitrogen deposition can be optimized, and nitrogen loss is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of animal feed, and in particular to a low-protein diet composition for growing pigs, a preparation method thereof, and a feeding method for pigs. Background Art

[0002] In modern animal husbandry, improving the growth performance of growing pigs is an important goal. Amino acids are the basic building blocks of proteins and are crucial for protein deposition in growing pigs. Currently, the amino acids supplemented in the diet are mainly monomeric amino acids, and these amino acids can be directly absorbed into the blood by intestinal epithelial cells without digestion and enter the liver through the portal vein for synthesis. However, the synthesis of proteins requires more than 20 kinds of amino acids to work together, and the other amino acids in the feed need to enter the blood through digestion and absorption in the gastrointestinal tract, resulting in the problem of asynchronous entry of amino acids into the portal vein. As a result, some amino acids undergo oxidative deamination, and some amino acids undergo transamination. According to animal nutrition theory, it is generally believed that the nutritional needs of animals to meet their life activities and production are mainly based on the types, quantities, and proportions of the provided available nutrients. Currently, the description of the nutritional value in feed is still based on the standard ileal digestible (SID) as the standard. However, many studies at home and abroad have shown that there are significant differences in growth performance and nitrogen deposition effects when using different protein sources to balance the diet with the same amount of ileal digestible amino acids at the end. There are also studies showing that there is a relationship between nitrogen deposition efficiency and the synchrony of amino acid release in the diet. The low-protein diet technology has received extensive attention due to its significant advantages in reducing feed costs, reducing nitrogen emissions, and improving feed utilization. Traditional low-protein diets mainly supplement synthetic amino acids to meet the nutritional needs of growing pigs, but this method ignores the impact of the dynamic release of amino acids from protein sources in the diet on animal growth. Corn gluten meal, as a common plant protein source, has the advantages of low cost and moderate protein content, but its amino acid release rate is slow, which may lead to uneven supply of amino acids in the digestive tract and affect the growth performance of growing pigs.

[0003] Therefore, it is very necessary to provide a feed that can improve the growth performance of growing pigs and promote nitrogen absorption. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a low-protein diet composition for growing pigs, and the low-protein diet composition for growing pigs provided by the present invention improves the growth performance of growing pigs and / or promotes nitrogen absorption.

[0005] When corn gluten meal is used as a protein source, the present invention achieves a significant combined effect through the dynamic characteristics of in vitro amino acid release of corn gluten meal and the synergistic effect of adding slow-release lysine and slow-release threonine, so as to improve the nitrogen deposition efficiency and growth performance of growing pigs.

[0006] The present invention provides a low-protein diet composition for growing pigs, comprising the following raw materials in parts by weight: 65.0 - 75.0 parts of corn, 10.0 - 15.0 parts of wheat bran, 5.0 - 10.0 parts of corn gluten meal, 1.0 - 2.0 parts of soybean oil, 0.5 - 1.0 parts of sodium chloride, 0.5 - 1.5 parts of stone powder, 1.0 - 1.5 parts of calcium hydrogen phosphate, 0.1 - 1.0 parts of lysine hydrochloride, 0.1 - 0.5 parts of threonine, 0.02 - 0.5 parts of tryptophan, 0.25 - 0.5 parts of slow-release lysine hydrochloride, 0.03 - 0.12 parts of slow-release threonine, and 1.0 part of premix.

[0007] In some specific embodiments of the present invention, the low-protein diet for growing pigs comprises the following raw materials in parts by weight: 67.0 - 74.0 parts of corn, 11.0 - 14.0 parts of wheat bran, 6.0 - 9.0 parts of corn gluten meal, 1.1 - 1.8 parts of soybean oil, 0.6 - 0.9 parts of sodium chloride, 0.6 - 1.4 parts of stone powder, 1.1 - 1.4 parts of calcium hydrogen phosphate, 0.2 - 0.8 parts of lysine hydrochloride, 0.1 - 0.4 parts of threonine, 0.02 - 0.4 parts of tryptophan, 0.3 - 0.5 parts of slow-release lysine hydrochloride, 0.05 - 0.1 parts of slow-release threonine, and 1.0 part of premix.

[0008] In some specific embodiments of the present invention, the low-protein diet for growing pigs comprises the following raw materials in parts by weight: 68.0 - 74.0 parts of corn, 12.0 - 13.0 parts of wheat bran, 7.0 - 9.0 parts of corn gluten meal, 1.1 - 1.6 parts of soybean oil, 0.7 - 0.9 parts of sodium chloride, 0.6 - 1.2 parts of stone powder, 1.1 - 1.3 parts of calcium hydrogen phosphate, 0.2 - 0.6 parts of lysine hydrochloride, 0.1 - 0.3 parts of threonine, 0.02 - 0.3 parts of tryptophan, 0.3 - 0.45 parts of slow-release lysine hydrochloride, 0.06 - 0.09 parts of slow-release threonine, and 1.0 part of premix.

[0009] In a specific embodiment of the present invention, the low-protein diet for growing pigs comprises the following raw materials in parts by weight: 73.2 parts of corn, 8.5 parts of corn gluten meal, 12.5 parts of wheat bran, 1.2 parts of soybean oil, 0.8 part of sodium chloride, 0.69 part of limestone powder, 1.18 parts of dicalcium phosphate, 0.28 part of lysine hydrochloride, 0.1 part of threonine, 0.08 part of tryptophan, 0.38 part of slow-release lysine hydrochloride, 0.09 part of slow-release threonine, 1 part of premix.

[0010] The crude protein content of the corn gluten meal in the present invention is 50% - 60%; preferably 53.35%.

[0011] The lysine salt in the present invention is preferably L - lysine hydrochloride.

[0012] The slow-release lysine hydrochloride in the present invention (ordered from Hangzhou Kangdequan Feed Co., Ltd., and its microcapsule material components are 10% - 30% of palm oil, 40% - 60% of stearic acid, 10% of hydroxypropyl methylcellulose (HPMC), 5% of ethyl cellulose (EC), 10% of chitosan, and 5% of sodium carboxymethylcellulose (CMC)). It shows gastric bypass and sustained release, reaches the release peak in 2 hours in the small intestine and is completely released within 6 hours; The slow-release threonine (ordered from Hangzhou Kangdequan Feed Co., Ltd., and its microcapsule material components are 10% - 30% of palm oil, 40% - 60% of stearic acid, 10% of hydroxypropyl methylcellulose (HPMC), 5% of ethyl cellulose (EC), 10% of chitosan, and 5% of sodium carboxymethylcellulose (CMC)). It shows gastric bypass and sustained release, reaches the release peak in 2 hours in the small intestine and is completely released within 6 hours; The present invention creatively utilizes the synergistic effect between the slow-release lysine salt and the slow-release threonine, effectively improves the amino acid release balance of the feed, promotes the growth and development of animals, and improves the conversion efficiency of the feed.

[0013] According to the present invention, the premix is composed of vitamin A, vitamin D, vitamin E, vitamin K, vitamin B1, vitamin B2, vitamin B6, vitamin B12, niacin, folic acid, calcium pantothenate, antioxidant, choline chloride, anhydrous cobalt sulfate, copper sulfate pentahydrate, ferrous sulfate, manganese monoxide, zinc sulfate, potassium iodide, and sodium selenite, and each kilogram of the diet contains 28,500 IU of vitamin A; 3,600 IU of vitamin D; 67.5 IU of vitamin E; 37.5 mg of vitamin K; 17.5 mg of vitamin B1; 215 mg of vitamin B2; 69 mg of vitamin B6; 0.075 mg of vitamin B12, 70 mg of niacin, 3 mg of folic acid, 0.375 mg of calcium pantothenate, 0.15 mg of antioxidant, 105 mg of choline chloride; 1 mg of anhydrous cobalt sulfate; 155 mg of copper sulfate pentahydrate; 145 mg of ferrous sulfate; 75 mg of manganese monoxide; 125 mg of zinc sulfate; 0.3 mg of potassium iodide; 0.3 mg of sodium selenite.

[0014] In the present invention, the amino acid release rate of corn gluten meal is slow in the initial stage of digestion, and the amino acid release ratio is uneven in the middle and later stages. The slow-release amino acids can continuously supplement in the stage where the amino acid release ratio is unbalanced, thereby achieving the dynamic balanced supply of amino acids. The core of the present invention lies in the combined effect of specific slow-release amino acids. By optimizing the release rate of slow-release amino acids, it forms a complement with the dynamic amino acid release of corn gluten meal, significantly improving the growth performance and feed utilization rate of growing pigs.

[0015] The test results show that the combination of adding slow-release lysine and slow-release threonine has a significant positive synergistic effect, which can optimize the nitrogen deposition effect, reduce nitrogen loss, and at the same time reduce feed cost and nitrogen emissions.

[0016] The present invention provides a preparation method for the low-protein diet composition for growing pigs described in any one of the above, comprising the following steps: Mix corn, wheat bran, corn gluten meal, soybean oil, sodium chloride, stone powder, calcium hydrogen phosphate, lysine hydrochloride, threonine, tryptophan, slow-release lysine hydrochloride, slow-release threonine, and the premix to obtain.

[0017] The present invention does not limit the above preparation method, and mixing well known to those skilled in the art can be used.

[0018] The present invention provides a low-protein diet feed for growing pigs, comprising the low-protein diet composition for growing pigs described in any one of the above technical solutions.

[0019] The low-protein diet feed for growing pigs provided by the present invention, including the above-mentioned low-protein diet composition for growing pigs, may further include other auxiliaries or excipients, including but not limited to enzyme preparations, probiotics, antibiotics (within the specified usage range), antioxidants, and mold inhibitors; the present invention does not limit them, and those well-known to those skilled in the art can be used.

[0020] Application of the low-protein diet composition for growing pigs provided by the present invention in improving the growth performance of growing pigs and / or promoting nitrogen absorption.

[0021] According to the present invention, the improvement of the growth performance of growing pigs includes increasing the total weight gain and daily weight gain and reducing the feed-to-meat ratio; The promotion of nitrogen absorption includes reducing urinary nitrogen and nitrogen excretion and increasing nitrogen retention and nitrogen deposition rate.

[0022] The present invention also provides a feeding method for pigs, feeding the low-protein diet composition for growing pigs as described above.

[0023] The pigs in the present invention are growing pigs aged 2 to 3 months, fed twice a day, and the feeding amount is 3 wt% to 5 wt% of the body weight.

[0024] Preferably, the pigs in the present invention are growing pigs aged 2 months, fed twice a day, and the feeding amount is 4 wt% of the body weight.

[0025] The present invention simulates the gastrointestinal digestion environment of growing pigs, conducts in vitro digestion tests on corn gluten meal, and measures the dynamic release of amino acids at different time points. The results show that the amino acid release rate of corn gluten meal is relatively slow in the initial stage of in vitro digestion (0 - 120 minutes), and the release rate increases after 120 minutes, but the overall release degree is still limited, indicating that it has certain anti-digestibility in the initial stage of digestion. As the digestion time extends, the amino acid release gradually increases, but the overall digestion rate is still relatively slow.

[0026] According to the dynamic release characteristics of amino acids in corn gluten meal, the release rate of slow-release amino acids is designed to enable continuous release of amino acids during the stage of unbalanced amino acid release ratio (mid-late stage) of corn gluten meal, so as to achieve dynamic balanced supply of amino acids. The slow-release amino acids are prepared by microencapsulation slow-release technology and added to the low-protein diet.

[0027] The present invention designs a low-protein diet formula based on corn gluten meal. By adjusting the proportion of corn gluten meal and the addition amount of slow-release amino acids, the amino acid supply of the diet is matched with the nutritional requirements of growing pigs. The release rate of the slow-release amino acids is designed to reach the peak within 2 hours of in vitro digestion, forming a complement to the amino acid release dynamics of corn gluten meal, ensuring the continuous supply of amino acids in the digestive tract, and thus optimizing the nutritional supply of growing pigs. The crude protein content of the low-protein diet is lower than that of the traditional diet, but through the combination of corn gluten meal and slow-release amino acids, it can meet the requirements of growing pigs for essential amino acids.

[0028] The feed of the present invention can improve the growth performance of pigs: through the combination of corn gluten meal and slow-release amino acids, the dynamic balanced supply of amino acids is achieved, significantly improving the daily weight gain and feed conversion rate of growing pigs.

[0029] Reduce nitrogen emissions: The low-protein diet reduces the excessive intake of protein, reduces the nitrogen emissions in feces and urine, reduces the generation of harmful gases such as ammonia, and improves the pig house environment.

[0030] Precise nutritional supply: Based on the amino acid release dynamic characteristics of corn gluten meal, the release rate of slow-release amino acids is designed to achieve the precise supply of amino acids and improve the health level of growing pigs. Description of the Drawings

[0031] Figure 1 In vitro amino acid release characteristics of corn gluten meal.

[0032] Figure 2 In vitro amino acid release characteristics of different slow-release lysine hydrochlorides. Among them, a is the in vitro amino acid release curve of slow-release Lys1 (10% palm oil + 60% stearic acid), b is the in vitro amino acid release curve of slow-release Lys2 (30% palm oil + 40% stearic acid), and c is the in vitro amino acid release curve of slow-release Lys3 (mixed by slow-release Lys1 and slow-release Lys2).

[0033] Figure 3 In vitro amino acid release characteristics of different slow-release threonines. Among them, a is the in vitro amino acid release curve of slow-release Thr1 (10% palm oil + 60% stearic acid), b is the in vitro amino acid release curve of slow-release Thr2 (30% palm oil + 40% stearic acid), and c is the in vitro amino acid release curve of slow-release Thr3 (mixed by slow-release Lys1 and slow-release Lys2). Detailed Embodiments

[0034] The present invention provides a low-protein diet composition for growing pigs, a preparation method thereof, and a feeding method for pigs. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they all fall within the protection scope of the present invention. The methods and applications of the present invention have been described through preferred embodiments. It is obvious that relevant personnel can make changes or appropriate alterations and combinations to the methods and applications in this article without departing from the content, spirit, and scope of the present invention to implement and apply the technology of the present invention.

[0035] It should be understood that the expression "one or more of..." individually includes each object recited after the expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0036] The terms "comprising", "having", or "containing", including the use of their grammatical synonyms, should generally be understood as open and non-restrictive, for example, not excluding other unrecited elements or steps, unless specifically stated otherwise or understood from the context.

[0037] In this application, the term "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural.

[0038] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items.

[0039] It should be understood that as long as the present invention is still operable, the order of steps or the order of performing certain actions is not important. In addition, two or more steps or actions can be carried out simultaneously.

[0040] The use of any and all examples or exemplary language in this article, such as "for example" or "including", is only intended to better illustrate the present invention and does not limit the scope of the present invention unless a claim is made. No language in this specification should be construed as indicating that any unclaimed element is essential for the practice of the present invention.

[0041] In addition, the numerical ranges and parameters used to define the present invention are approximate values. The relevant values in the specific embodiments have been presented as precisely as possible herein. However, any numerical value inherently inevitably contains standard deviations caused by individual testing methods. Therefore, unless otherwise clearly stated, it should be understood that all ranges, quantities, numerical values, and percentages used in this disclosure are modified by "about". Herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific numerical value or range.

[0042] It should be understood that in various embodiments of the present application, the magnitudes of the serial numbers of the above processes do not imply the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0043] Some cases are recorded in the embodiments and comparative examples of the present invention, and some implementation manners of the present invention are shown in the embodiments. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0044] To further illustrate the present invention, the following describes in detail a low-protein diet composition for growing pigs provided by the present invention, its preparation method, and a method for raising pigs in combination with embodiments.

[0045] Control Example 1, Feed for Growing Pigs of 30 - 60 kg (without slow-release amino acids) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.66% lysine hydrochloride, 0.19% threonine, 0.08% tryptophan, and 1% premix.

[0046] Control Example 2, Feed for Growing Pigs of 30 - 60 kg (all lysine hydrochloride is slow-release lysine hydrochloride) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.66% slow-release lysine hydrochloride, 0.19% threonine, 0.08% tryptophan, and 1% premix.

[0047] Control Example 3, Feed for Growing Pigs of 30 - 60 kg (all threonine is slow-release threonine) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.66% lysine hydrochloride, 0.19% slow-release threonine, 0.08% tryptophan, and 1% premix.

[0048] Example 1. Feed for growing pigs weighing 30 - 60 kg (containing slow-release lysine) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.28% lysine salt, 0.19% threonine, 0.08% tryptophan, 0.38% slow-release lysine salt, and 1% premix.

[0049] Example 2. Feed for growing pigs weighing 30 - 60 kg (containing slow-release threonine) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.66% lysine salt, 0.1% threonine, 0.08% tryptophan, 0.09% slow-release threonine, and 1% premix.

[0050] Example 3. Feed for growing pigs weighing 30 - 60 kg (containing different combinations of slow-release amino acids) It consists of 73.2% corn, 8.5% corn gluten meal with a crude protein content of 53.35%, 12.5% wheat bran, 1.2% soybean oil, 0.8% sodium chloride, 0.69% limestone powder, 1.18% calcium hydrogen phosphate, 0.28% lysine salt, 0.1% threonine, 0.08% tryptophan, 0.38% slow-release lysine salt, 0.09% slow-release threonine, and 1% premix.

[0051] Test Example 1 Materials and Methods 1.1 Test Materials Control Examples 1 - 3, and the feeds of Examples 1 - 3.

[0052] 1.2 Test Design For this growth test, healthy three-way crossbred (Duroc × Landrace × Yorkshire) pigs with an initial body weight of (30 ± 0.5) kg (half castrated male pigs and half female pigs) were selected and randomly divided into 6 treatment groups according to body weight and gender, with 4 replicates in each treatment and 3 pigs in each replicate.

[0053] For the digestion and metabolism trial, healthy three-way crossbred (Duroc×Landrace×Yorkshire) pigs with an initial body weight of (30±0.5) kg (half castrated male pigs and half female pigs) were selected. They were randomly divided into 6 treatment groups according to body weight and gender, with 4 replicates in each treatment and one pig in each replicate. The pigs were randomly placed into stainless steel metabolism cages with slatted floors for total feces and urine collection. The trial period was 15 days, including a 3-day adaptation period, a 7-day pre-feeding period, and a 5-day feces and urine collection period.

[0054] 1.3 Experimental diets The trial used control examples 1 - 3 and the feeds of examples 1 - 3. The formula is shown in Table 1, and the nutrient composition is shown in Table 2.

[0055] 1.4 Feeding and management This trial was conducted at the animal experiment center base of Jilin Agricultural University. The temperature, humidity, and ventilation in the shed were automatically controlled, and the temperature in the shed was maintained at 20 - 23°C. The experimental pigs were housed individually in cages (1.8×1.2 m 2 ), equipped with a body weight weighing device, a stainless steel adjustable feed trough, and a nipple drinker. They were fed with powdered feed. The daily feeding amount was calculated at 4% of the body weight and fed twice at 7:30 am and 15:30 pm. The daily feed intake and the amount of wasted feed were accurately recorded. The pig shed was cleaned and flushed every day to keep the pig shed environment clean and hygienic. Deworming and immunization were carried out according to the conventional management procedures.

[0056] The digestion and metabolism trial was conducted at the animal experiment center base of Jilin Agricultural University. The temperature, humidity, and ventilation in the shed were automatically controlled, and the temperature in the shed was maintained at 20 - 23°C. The experimental pigs were housed individually in cages (1.8×1.2 m 2 ), equipped with a body weight weighing device, a stainless steel adjustable feed trough, and a nipple drinker. They were fed with powdered feed. The daily feeding amount was calculated at 4% of the body weight and fed twice at 7:30 am and 15:30 pm. The daily feed intake and the amount of wasted feed were accurately recorded. The pig shed was cleaned and flushed every day to keep the pig shed environment clean and hygienic.

[0057] 1.5 Sample collection On the last day, the pigs were weighed before feeding. 10 mL of blood was collected from the anterior vena cava using a 20 mL syringe and divided equally into a non-anticoagulant blood collection tube and a heparin sodium anticoagulant blood collection tube, 5 mL each. After standing at room temperature for 30 min, it was centrifuged at 3500 rpm for 10 min to separate the serum and plasma, which were then aliquoted into enzyme-free centrifuge tubes for blood biochemical index detection.

[0058] For the digestion and metabolism trial, feces and urine were collected using the total fecal and urinary collection method. After removing feed, pig hair, and dander from the fecal samples, 6N HCl was added for nitrogen fixation, and the samples were stored frozen at -20°C. At the end of the 5-day collection period, the feces of each pig over 5 days were mixed, weighed, and sampled by quartering to approximately 300 g. The samples were dried in an oven at 65°C for 72 h until constant weight and then pulverized for testing. Urine samples were accurately collected for the urine excreted in 24 h, thoroughly mixed, the volume was recorded, 50 mL was sampled, and stored frozen at -20°C for testing.

[0059] 1.6 Detection indicators (1) Growth performance Individual weight and feed consumption were recorded, and average daily gain, average daily feed intake, and feed-to-gain ratio were calculated.

[0060] (2) Nitrogen deposition indicators The contents of dry matter, crude protein, and urinary nitrogen in the fecal samples of the digestion and metabolism trial were determined.

[0061] Nitrogen intake (NI) = Feed nitrogen content × Average daily feed intake; Fecal nitrogen output (FN) = Fecal nitrogen content × Average daily total fecal weight; Urinary nitrogen output (UN) = Urinary nitrogen content × Average daily total urine volume; Total nitrogen output (TN) = FN + UN; Nitrogen retention (RN) = NI - TN; Apparent nitrogen digestibility (AND) = (NI - FN) / NI × 100%; Net protein utilization (NPU) = RN / NI × 100%; Apparent biological value of protein (ABV) = RN / (NI - FN) × 100%.

[0062] 1.7 Statistical methods The experimental data were statistically analyzed using SPSS 23.0 statistical software. A P value < 0.05 was considered significantly different, and a P value < 0.01 was considered extremely significantly different.

[0063] 2 Results and discussion of the analysis of the in vitro amino acid release dynamic characteristics of corn gluten meal Figure 1 The in vitro amino acid release characteristics of corn gluten meal; Through Figure 1It shows that the amino acid release characteristics of corn gluten meal present a phased pattern during in vitro digestion: the overall release rate is slow in the initial stage of digestion (0 - 120 minutes), significantly accelerates in the middle stage (120 - 240 minutes), and gradually stabilizes in the later stage (240 - 360 minutes). This release pattern indicates that corn gluten meal can rapidly release lysine in the middle stage of digestion. However, the lysine release amount of corn gluten meal is low in the initial stage of digestion, which may not meet the high demand of growing pigs for lysine, and the release rate slows down in the later stage, which may lead to insufficient lysine supply. Therefore, in practical applications, corn gluten meal may need to optimize the amino acid balance by adding synthetic lysine or slow-release lysine to better meet the nutritional requirements of growing pigs.

[0064] Analysis of the in vitro amino acid release dynamic characteristics of slow-release amino acids Figure 2 In vitro amino acid release characteristics of different slow-release lysine hydrochlorides.

[0065] Figure 3 In vitro amino acid release characteristics of different slow-release threonines.

[0066] Through Figure 2 and Figure 3 It shows that in the experiment, the release curves of slow-release Lys1 (10% palm oil + 60% stearic acid) and slow-release Lys2 (30% palm oil + 40% stearic acid) did not fully match the dynamic release pattern of corn gluten meal. The release rates of slow-release Lys1 and slow-release Thr1 were relatively fast in the initial stage of the experiment, but then quickly stabilized, with a relatively short overall release time; while the release rates of slow-release Lys2 and slow-release Thr2 were relatively low and stable. Although they could achieve a long-term slow-release effect, the release rate in the initial stage was slow and could not meet the demand for rapid release. In contrast, the release characteristics of slow-release Lys3 (a mixture of slow-release Lys1 and slow-release Lys2) and slow-release Thr3 (a mixture of slow-release Thr1 and slow-release Thr2) were closer to the dynamic release pattern of corn gluten meal. It could rapidly release a certain amount of lysine in the initial stage to meet the demand in the initial stage; then the release rate gradually slowed down and entered a relatively stable slow-release stage, which could continuously release lysine for a long time. This mixed formula better simulated the amino acid dynamic release characteristics of corn gluten meal during digestion through the combined effect. The slow-release amino acids in the following formulas are all slow-release amino acids of the mixed formula.

[0067] Table 1 Composition of experimental diets

[0068] Note: The 1% premix provides per kilogram of diet: Vitamin A 28,500 IU; Vitamin D3 6,000 IU; Vitamin E 67.5 IU; Vitamin K3 7.5 mg; Vitamin B1 17.5 mg; Vitamin B2 215 mg; Vitamin B6 69 mg; Vitamin B12 0.075 mg, Niacin 70 mg, Folic acid 3 mg, Calcium pantothenate 0.375 mg, Antioxidant 0.15 mg, Choline chloride 105 mg; Cobalt sulfate anhydrous 1 mg; Copper sulfate pentahydrate 155 mg; Ferrous sulfate 145 mg; Manganese monoxide 75 mg; Zinc sulfate 125 mg; Potassium iodide 0.3 mg; Sodium selenite 0.3 mg. Table 2 Nutritional levels of the diet

[0069] 2.1 Effects of different feeds on the growth performance of growing pigs The results of the effects of different feeds on the growth performance of growing pigs are shown (see Table 3 for details). Significant differences were observed among the experimental groups in terms of average total weight gain, average daily weight gain, and feed-to-meat ratio. Specifically, the average total weight gain (16.6 ± 0.7 kg) and average daily weight gain (0.92 ± 0.04 kg) of Example 3 were the highest and significantly higher than those of Control Example 1 (P < 0.05). The average total weight gain and average daily weight gain of Example 1 and Example 2 were also significantly higher than those of Control Example 1 (P < 0.05), but there was no significant difference from Example 3 (P > 0.05).

[0070] Table 3 Effects of different feeds on the growth performance of growing pigs

[0071] Note: Different letters marked in the same row of the above table indicate significant differences (P < 0.05). The same applies to the following tables.

[0072] In terms of the feed-to-meat ratio, the feed-to-meat ratio of Example 3 was the lowest (2.48 ± 0.11), significantly lower than that of Control Example 1 (P < 0.05), indicating the highest feed conversion efficiency. The feed-to-meat ratios of Example 1 and Example 2 were also significantly lower than that of Control Example 1 (P < 0.05), but there was no significant difference from Example 3 (P > 0.05). The average total weight gain, average daily weight gain, and feed-to-meat ratio of Control Example 2 and Control Example 3 were all between those of the Examples and Control Example 1, and there were significant differences compared with Control Example 1 (P < 0.05), but there was no significant difference between the two groups (P > 0.05). This indicates that adding appropriate proportions of slow-release lysine and slow-release threonine can effectively improve the amino acid balance of the feed, promote the growth and development of animals, and improve the feed conversion efficiency. Among them, the comprehensive performance of Example 3 was the most excellent, indicating that the combined addition of slow-release lysine and slow-release threonine has a synergistic effect on promoting animal growth.

[0073] 2.2 Effects of Different Feeds on Nitrogen Deposition in Growing Pigs The experimental results of the effects of different feeds on nitrogen deposition in growing pigs showed that: the differences in nitrogen intake (NI) among groups were small, ranging from 26.75 to 27.46 g / d, indicating that the feed formula had limited influence on the total nitrogen intake. There was no significant difference in fecal nitrogen (FN) excretion among groups, all between 8.53 and 8.55 g / d. However, there were significant differences in urinary nitrogen (UN) excretion among different groups (P<0.05), with the highest urinary nitrogen excretion in the control group (5.12 g / d), and the lowest in Example 3 (corn protein powder + slow-release lysine + slow-release threonine) (4.4 g / d). Nitrogen excretion (NE) also showed a similar trend, with the lowest nitrogen excretion in Example 3 (12.94 g / d), significantly lower than that in the control example (13.66 g / d). The nitrogen retention (ND) and nitrogen deposition rate (NDR) both reached the highest values in Example 3, which were 14.44 g / d and 52.74% respectively, significantly higher than those in other groups (P<0.05), and the results are shown in Table 4.

[0074] Table 4 Effects of Different Feeds on Nitrogen Deposition in Growing Pigs

[0075] The results showed that: the addition of slow-release lysine, slow-release threonine or their combination had a significant impact on the nitrogen metabolism of animals. The reduction of urinary nitrogen and nitrogen excretion, as well as the increase of nitrogen retention and nitrogen deposition rate, indicated that the feed formula in the examples could more effectively promote nitrogen absorption and utilization and reduce nitrogen waste. Especially Example 3 (corn protein powder + slow-release lysine + slow-release threonine) showed the best performance in terms of nitrogen retention and nitrogen deposition rate, indicating that its feed formula could significantly improve the nitrogen utilization efficiency of animals, thereby promoting protein synthesis and deposition. Although the biological value of protein had little difference among groups, the slight increase in Example 3 also reflected its advantage in protein utilization efficiency. In summary, the addition of slow-release lysine and slow-release threonine to corn protein powder could significantly improve the nitrogen metabolism efficiency of animals, reduce nitrogen excretion, increase nitrogen retention and deposition, thus optimizing protein synthesis and utilization. This result provided an important reference for optimizing feed formula, improving feed utilization rate and reducing breeding costs.

[0076] Calculation Method for Synergy Parameters The main parameters directly affecting the growth performance of growing pigs were reflected by two indicators: nitrogen deposition rate and retained nitrogen. Therefore, through data standardization transformation, with the diet without adding slow-release amino acids set as 0, the obtained data are shown in Table 5: Table 5 Effects of Different Feeds on Nitrogen Deposition in Growing Pigs (Results of Data Standardization)

[0077] Wherein, > 0, the value higher than the control group compared with the control group; < 0, the value lower than the control group compared with the control group.

[0078] Synergy parameter (SP) The synergy parameter is used to evaluate whether the combined effect is better than the product of the individual effects: X combination: The effect of Example 3.

[0079] X single factor 1: The effect of Example 1.

[0080] X single factor 2: The effect of Example 2).

[0081] Combination index (CI) The combination index is used to evaluate whether the combined effect is better than the sum of the individual effects: CI < 1: Positive synergy effect.

[0082] CI = 1: No synergy effect.

[0083] CI > 1: Negative synergy effect.

[0084] Synergy coefficient (CC) The synergy coefficient is used to quantify the difference between the combined effect and the individual effects: CC > 0: Positive synergy effect.

[0085] CC = 0: No synergy effect.

[0086] CC < 0: Negative synergy effect.

[0087] Calculation results Nitrogen deposition rate (NDR) Synergy parameter (SP): SP NDR = = 32.7 Combination index (CI): CI NDR = = 1.57 Synergy coefficient (CC): CC NDR = = 0.57 Nitrogen retention (ND, g / d) Synergy parameter (SP): SP ND =-26.3 Combination Index (CI): CI ND =1.74 Coefficient of Coordination (CC): CC ND =0.74 Analysis and Conclusion Nitrogen Deposition Rate (NDR) Synergy Parameter (SP = 32.7): The combined effect is much higher than the product of individual effects, indicating a significant positive synergy effect.

[0088] Combination Index (CI = 1.57): The combined effect is higher than the sum of individual effects, indicating a synergy effect.

[0089] Coefficient of Coordination (CC = 0.57): The combined effect is significantly better than the sum of individual effects, indicating a positive synergy effect.

[0090] Nitrogen Retention (ND, g / d) Synergy Parameter (SP = -26.3): The negative value indicates a significant difference between the combined effect and the product of individual effects, but the negative value of SP may be affected by the negative value in Example 2.

[0091] Combination Index (CI = 1.74): The combined effect is higher than the sum of individual effects, indicating a synergy effect.

[0092] Coefficient of Coordination (CC = 0.74): The combined effect is significantly better than the sum of individual effects, indicating a positive synergy effect.

[0093] Verified by Bliss Independence Model The Bliss model assumes that two drugs act independently, and the combined effect is: Calculate CI: CI > 1: Synergistic effect; CI = 1: Additive effect; CI < 1: Antagonistic effect.

[0094] Calculation Results: Nitrogen Deposition Rate (NDR): E AB =0.0313+0.006-0.0313*0.006=0.0372 CI NDR=0.0603 / 0.0372 = 1.62 Conclusion: CI > 1, indicating a synergistic effect exists.

[0095] Nitrogen retention (ND): E AB =0.0434 + (-0.0060) - 0.0434 * (-0.0060) = 0.0378 CI ND =0.0693 / 0.0378 = 1.83 Conclusion: CI > 1, indicating a synergistic effect exists.

[0096] Through the synergistic effect analysis of nitrogen deposition rate (NDR) and nitrogen retention (ND) for different examples (corn gluten meal, corn gluten meal + slow-release lysine (Lys), corn gluten meal + slow-release threonine (Thr), corn gluten meal + slow-release lysine + slow-release threonine (CGM + Lys + Thr)), this study found that the combined addition of slow-release lysine (Lys) and slow-release threonine (Thr) has a significant positive synergistic effect on nitrogen deposition.

[0097] Specifically, the calculation results of the synergistic parameter (SP), combination index (CI), and synergistic coefficient (CC) of nitrogen deposition rate (NDR) and nitrogen retention (ND) show that the combined addition of appropriate proportions of slow-release Lys and slow-release Thr can significantly improve the nitrogen deposition efficiency and retention. Among them, the synergistic coefficient (CC) of nitrogen deposition rate (NDR) is 0.57, and the synergistic coefficient (CC) of nitrogen retention (ND) is 0.74, both of which are significantly greater than 0, indicating that the combined addition has a significant positive synergistic effect on nitrogen deposition. This result shows that the combined use of appropriate proportions of slow-release lysine and slow-release threonine can effectively improve the nitrogen utilization efficiency, reduce nitrogen loss, and thus enhance the overall nitrogen deposition effect.

[0098] Therefore, this study proposes that by combining and adding appropriate proportions of slow-release lysine (Lys) and slow-release threonine (Thr), the nitrogen deposition effect can be significantly optimized, which has important application value. This discovery provides a new technical idea for improving nitrogen utilization efficiency and reducing environmental pollution, and can be widely applied in related fields.

[0099] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A low-protein diet composition for growing pigs, characterized in that: The invention comprises the following raw materials in parts by weight: 65.0-75.0 parts of corn, 10.0-15.0 parts of wheat bran, 5.0-10.0 parts of corn gluten meal, 1.0-2.0 parts of soybean oil, 0.5-1.0 parts of sodium chloride, 0.5-1.5 parts of stone powder, 1.0-1.5 parts of calcium hydrogen phosphate, 0.1-1.0 parts of lysine hydrochloride, 0.1-0.5 parts of threonine, 0.02-0.5 parts of tryptophan, 0.25-0.5 parts of sustained-release lysine hydrochloride, 0.03-0.12 parts of sustained-release threonine and 1.0 parts of premix.

2. The low-protein diet composition for growing pigs according to claim 1, characterized in that: The low-protein diet for growing pigs includes the following raw materials in parts by weight: 67.0~74.0 parts of corn, 11.0~14.0 parts of wheat bran, 6.0~9.0 parts of corn gluten meal, 1.1~1.8 parts of soybean oil, 0.6~0.9 parts of sodium chloride, 0.6~1.4 parts of stone powder, 1.1~1.4 parts of calcium hydrogen phosphate, 0.2~0.8 parts of lysine hydrochloride, 0.1~0.4 parts of threonine, 0.02~0.4 parts of tryptophan, 0.3~0.5 parts of sustained-release lysine hydrochloride, 0.05~0.1 parts of sustained-release threonine and 1.0 parts of premix.

3. The low-protein diet composition for growing pigs according to claim 2, characterized in that: The low-protein diet for growing pigs includes the following raw materials in parts by weight: 73.2 parts of corn, 8.5 parts of corn gluten meal, 12.5 parts of wheat bran, 1.2 parts of soybean oil, 0.8 parts of sodium chloride, 0.69 parts of stone powder, 1.18 parts of calcium hydrogen phosphate, 0.28 parts of lysine hydrochloride, 0.1 parts of threonine, 0.08 parts of tryptophan, 0.38 parts of sustained-release lysine hydrochloride, 0.09 parts of sustained-release threonine and 1.0 parts of premix.

4. The low-protein diet composition for growing pigs according to claim 1, characterized in that: The sustained-release lysine hydrochloride is a gastric sustained-release, reaching a release peak in the small intestine after 2 hours and being completely released within 6 hours; The sustained-release threonine is a gastric sustained-release, reaching a release peak in the small intestine after 2 hours and being completely released within 6 hours; The premix consists of vitamin A, vitamin D, vitamin E, vitamin K, vitamin B1, vitamin B2, vitamin B6, vitamin B12, niacin, folic acid, calcium pantothenate, antioxidant, choline chloride, anhydrous cobalt sulfate, copper sulfate pentahydrate, ferrous sulfate, manganese monoxide, zinc sulfate, potassium iodide and sodium selenite, and contains 28500 IU of vitamin A, 36000 IU of vitamin D, 67.5 IU of vitamin E, 37.5 mg of vitamin K, 17.5 mg of vitamin B1, 215 mg of vitamin B2, 69 mg of vitamin B6, 0.075 mg of vitamin B12, 70 mg of niacin, 3 mg of folic acid, 0.375 mg of calcium pantothenate, 0.15 mg of antioxidant, 105 mg of choline chloride, 1 mg of anhydrous cobalt sulfate, 155 mg of copper sulfate pentahydrate, 145 mg of ferrous sulfate, 75 mg of manganese monoxide and 125 mg of zinc sulfate per kilogram of diet. mg; potassium iodide 0.3 mg; sodium selenite 0.3 mg.

5. A method for preparing a low-protein diet composition for growing pigs according to any one of claims 1 to 4, characterized in that: The steps include: The preparation method is prepared by mixing corn, wheat bran, corn protein powder, soybean oil, sodium chloride, stone powder, calcium hydrogen phosphate, lysine hydrochloride, threonine, tryptophan, slow-release lysine hydrochloride, slow-release threonine and premix.

6. A low-protein diet feed for growing pigs, characterized in that: The invention comprises the low-protein diet composition for growing pigs according to any one of claims 1 to 4.

7. Use of the low-protein diet composition for growing pigs according to any one of claims 1 to 4 in improving the growth performance of growing pigs and / or promoting nitrogen absorption.

8. The use according to claim 7, characterized in that: The improvement of the growth performance of growing pigs includes increasing the total weight gain and daily weight gain and reducing the feed-to-meat ratio; the promotion of nitrogen absorption includes reducing urinary nitrogen and nitrogen excretion and increasing nitrogen retention and nitrogen deposition rate.

9. A method for raising pigs, characterized in that: Feeding the growing pigs with the low-protein diet composition according to any one of claims 1 to 4.

10. The breeding method according to claim 9, characterized in that: The pigs are growing pigs aged 2 to 3 months and are fed twice a day at a feeding amount of 3 wt% to 5 wt% of their body weight.

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