Ruminant feed based on aged corn and laminarin and application of ruminant feed

Abstract

The invention discloses ruminant feed based on aged corn and laminarin and application of the ruminant feed, and belongs to the technical field of animal feed. The aged corn is used for replacing common corn to serve as a main energy raw material, 0.5% of laminarin is added, and the problems of growth inhibition, oxidative stress, rumen microecological imbalance and the like caused by the aged corn are solved. Tests show that the feed can significantly improve the average daily gain, the nutrition digestibility and the antioxidant capacity of the Hu sheep, improve the meat quality and reduce the breeding cost, and a new way is provided for reasonable utilization of the aged corn.

Description

Technical Field

[0001] This invention relates to the field of animal feed technology, and in particular to a ruminant feed based on aged corn and kelp polysaccharides and its application. Background Technology

[0002] Corn kernels maintain biological activity throughout storage, participating in continuous metabolic cycles such as aerobic respiration, biochemical aging, and programmed aging. Corn kernels have large embryos and high fat content, exhibiting strong life activities and high respiration rates, making them prone to oxidative rancidity. With increasing storage time, the activity of redox enzymes in the kernels decreases, respiration weakens, and physicochemical properties change, leading to a deterioration in both seed and edible quality. This process is known as corn aging, resulting in aged corn (AC).

[0003] According to the "Rules for Judging the Storage Quality of Corn" (GB / T 20570-2015), the storage quality of corn is judged by fatty acid value (FAV), color, odor and taste score. Corn with a fatty acid value ≥78mgKOH / 100g is defined as "severely unsuitable for storage".

[0004] During storage, the nutritional components and physicochemical properties of corn undergo significant changes: the starch structure increases due to the degradation of amylopectin, leading to an increased ratio of amylose to amylopectin; proteins denature due to oxidation, resulting in a decrease in free sulfhydryl groups and the formation of disulfide bonds; lipids decrease in unsaturated fatty acid content due to peroxidation, and oxidation products such as malondialdehyde accumulate; the activity of antioxidant enzymes such as superoxide dismutase and catalase decreases, leading to the accumulation of reactive oxygen species; and there is a potential risk of contamination by mycotoxins such as aflatoxin and zearalenone. Furthermore, aged corn darkens in color, develops a poorer odor, and its palatability significantly decreases.

[0005] Although the conventional nutritional components of aged corn are similar to those of regular corn, its oxidation products, anti-nutritional factors, and decreased palatability limit its application in animal production. Existing research indicates that feeding animals with aged corn can cause multiple negative effects: it reduces average daily weight gain and increases feed conversion ratio; one study found that replacing 30% of regular corn with aged corn significantly reduced the final weight and average daily weight gain of broiler ducks. Aged corn also inhibits the apparent digestibility of crude protein, neutral detergent fiber, and acid detergent fiber, possibly due to changes in starch structure leading to increased resistant starch and protein denaturation reducing digestive enzyme contact efficiency. Furthermore, aged corn induces oxidative stress, manifested as elevated malondialdehyde (MDA) levels in plasma, liver, and intestines, and increased superoxide dismutase (SOD) levels. The activity of antioxidant enzymes such as glutathione peroxidase and glutathione peroxidase is reduced, which in turn damages cell membrane integrity and affects mitochondrial function. In terms of meat quality, aged corn accelerates the decline of muscle pH after slaughter, reduces meat color stability, and reduces the content of essential amino acids such as proline. At the same time, lipid peroxidation products affect the flavor and sensory quality of meat. In terms of rumen microecology, aged corn changes rumen fermentation parameters, leading to a decrease in the content of ammonia nitrogen, microbial protein and volatile fatty acids, inhibiting the abundance of beneficial bacteria such as Prevotella, and disrupting key pathways such as tryptophan metabolism and purine metabolism.

[0006] Kelp polysaccharides are natural active substances extracted from brown algae, mainly composed of fucoidan, alginate, and kelp starch. They possess antioxidant, immunomodulatory, and digestive tract flora regulation functions. They exert their antioxidant effects by scavenging free radicals such as hydroxyl radicals and superoxide anions, increasing the activity of superoxide dismutase and catalase, and reducing malondialdehyde content. They achieve immunomodulation by inhibiting the release of inflammatory factors such as tumor necrosis factor-α and interleukin-6, thereby enhancing intestinal barrier function. Furthermore, they improve the digestive tract microecology by promoting the proliferation of beneficial bacteria such as Bifidobacteria and Lactobacillus, increasing the production of short-chain fatty acids.

[0007] However, existing research focuses on the application of kelp polysaccharides in monogastric animals such as pigs and chickens, with limited research on ruminants such as Hu sheep. Furthermore, there is a lack of systematic reports on the mitigation effects and mechanisms of kelp polysaccharides on oxidative stress, decreased production performance, and deterioration of meat quality caused by aged corn, which limits the efficient utilization of aged corn in ruminant feed.

[0008] With increasing demand for feed and rising grain prices, using ordinary corn as a feed ingredient leads to increased breeding costs. Although aged corn (AC) is not significantly different from ordinary corn in terms of conventional nutritional components, it has a higher content of peroxidation products, which may have adverse effects on ruminants during feeding. Therefore, this invention aims to explore the effects of aged corn replacing ordinary corn on the growth performance, antioxidant function, and meat quality of Hu sheep, and to improve the feeding effect of aged corn by adding kelp polysaccharides to the feed containing aged corn. Summary of the Invention

[0009] The purpose of this invention is to provide a ruminant feed based on aged corn and kelp polysaccharides and its application, in order to provide data support for the rational utilization of aged corn and improve feed resource utilization, and to provide a theoretical basis for the rational utilization of aged corn in animal production.

[0010] To achieve the above objectives, on the one hand, the present invention provides a ruminant feed based on aged corn and kelp polysaccharide, wherein the corn in the ruminant feed is replaced by aged corn in equal proportion and 0.5% kelp polysaccharide is added on a dry matter basis.

[0011] Preferably, the ruminant feed, on a dry matter basis, comprises the following raw materials in the following weight percentages: 30% sheepgrass, 32.76% aged corn, 14% sprayed corn husk, 3.5% corn germ meal, 10.5% DDGS, 5.6% soybean meal, 0.7% beet molasses, 1.05% limestone powder, 0.42% slow-release ammonium chloride, 0.42% sodium chloride, 0.42% dicalcium phosphate, 0.35% sodium bisulfate, 0.28% compound premix, and 0.5% kelp polysaccharide.

[0012] Preferably, the kelp polysaccharide has a purity of ≥98% and a sulfate content of ≥28%.

[0013] On the other hand, the present invention provides an application of the above-mentioned ruminant feed based on aged corn and kelp polysaccharides in improving the production performance, antioxidant function and meat quality of ruminants.

[0014] Therefore, this invention provides a ruminant feed based on aged corn and kelp polysaccharides and its application. By adding kelp polysaccharides to the aged corn diet, the negative effects of aged corn on ruminants are significantly alleviated. The specific technical effects are as follows:

[0015] (1) Improve growth performance and increase feed utilization efficiency: When aged corn was fed alone, it significantly reduced the average daily weight gain of Hu sheep and increased the feed conversion ratio. However, after adding kelp polysaccharide, the average daily weight gain increased from 126.23 g / d to 153.25 g / d, which is close to the control group of 165.45 g / d. The feed conversion ratio decreased from 10.76 to 8.33, which is close to the control group of 7.90. This indicates that kelp polysaccharide can effectively alleviate the growth inhibition caused by aged corn and improve feed conversion efficiency.

[0016] (2) Improved apparent digestibility of nutrients: The apparent digestibility of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in the aged corn group was significantly reduced. However, after the addition of kelp polysaccharide, the digestibility of crude protein increased from 30.75% to 42.37%, close to the control group's 45.39%, the neutral detergent fiber increased from 34.78% to 42.26%, close to the control group's 44.00%, and the acid detergent fiber increased from 41.18% to 45.58%. This indicates that kelp polysaccharide can improve the nutrient digestibility disorder caused by aged corn and promote the absorption of protein and fiber.

[0017] (3) Enhance the body's antioxidant function and alleviate oxidative stress: The malondialdehyde content in the muscle, plasma and intestine of the aged corn group was significantly increased, and the activities of superoxide dismutase, glutathione peroxidase and total antioxidant capacity were significantly reduced; after adding kelp polysaccharide, the malondialdehyde content in the muscle decreased by about 20%, the malondialdehyde content in the plasma decreased by about 30%, and the activity of superoxide dismutase in the plasma increased by about 25% and the total antioxidant capacity increased by about 20%. The total antioxidant capacity and catalase activity in the liver were significantly improved, and the reactive oxygen species content in the intestine decreased by about 15%. This indicates that kelp polysaccharide can effectively alleviate the oxidative stress induced by aged corn by scavenging free radicals and enhancing antioxidant enzyme activity.

[0018] (4) Optimization of rumen fermentation and microecological homeostasis: The contents of rumen ammonia nitrogen (NH3-N), microbial protein (MCP), acetic acid, butyric acid and total volatile fatty acids (VFAs) in the aged corn group were significantly reduced. However, after the addition of kelp polysaccharide, the rumen environment affected by the aged corn was restored to a level similar to that of normal diet feeding. This indicates that the trace elements in kelp polysaccharide, such as iodine, potassium and magnesium, can participate in various metabolic reactions in the rumen and indirectly promote rumen fermentation. As a prebiotic, kelp polysaccharide has certain spatial structure and chemical properties, which can play a role in stabilizing enzyme structure, improving enzyme activity, promoting the growth of beneficial bacteria and optimizing the microbial community structure in the rumen environment.

[0019] (5) Improve meat quality and maintain muscle nutritional value: The yellowness of the meat (b*) in the aged corn group was significantly reduced, and the proline content in the muscle showed a downward trend. After adding kelp polysaccharide, the pH of the muscle increased from 4.36 to 5.1 45 minutes after slaughter, which was significantly higher than the 4.38 of the control group. This slowed down the rate of pH decay, restored the yellowness of the meat to the level of the control group, and alleviated the downward trend of proline content. It also maintained the stability of the amino acid composition of the muscle and improved the sensory quality and nutritional value of the meat.

[0020] (6) Realize the resource utilization of aged corn and reduce breeding costs: This invention uses severely aged corn (fatty acid value ≥78mg KOH / 100g) that is not suitable for storage as the main energy raw material. By adding kelp polysaccharide to offset its negative effects, the amount of high-priced ordinary corn used is reduced while ensuring the production performance of ruminants, thus reducing feed costs and providing a feasible way for the large-scale and safe utilization of aged corn.

[0021] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0022] The technical solution of the present invention will be further described below through embodiments.

[0023] To make the objectives, technical solutions, and advantages of this application clearer, more thorough, and more complete, the technical solutions of the present invention are clearly and completely described below through embodiments. The following detailed descriptions are all illustrations of embodiments, intended to provide further detailed explanations of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] The aged and regular corn used in the following examples were purchased from grain depots around Harbin, Heilongjiang Province, and their storage was carried out under the conditions specified in (GB / T 7415—2008): the warehouses had ventilation facilities, were kept dry, and the seeds were at least 200mm above the ground and at least 500mm from the top of the warehouse; the bagged corn was stacked in a "non-standard" shape, a semi-non-standard shape, or in piles, at least 500mm from the wall. The storage time for regular corn was 1 year, and the storage time for aged corn was 4 years. The mycotoxin content of both was lower than the limit specified in the National Feed Hygiene Standard (GB 13078-2017). The aflatoxin B1 content was 3.6 μg / kg, which is lower than the standard limit of 30 μg / kg; the zearalenone content was 0.12 mg / kg, which is lower than the standard limit of 0.5 mg / kg; the vomitoxin content was 0.62 mg / kg, which is lower than the standard limit of 5 mg / kg; the ochratoxin A content was lower than 2.0 μg / kg, which is lower than the standard limit of 100 μg / kg; the fumonisin content was 0.85 mg / kg, which is lower than the standard limit of 60 mg / kg; and the T-2 toxin content was 0.15 mg / kg, which is lower than the standard limit of 0.5 mg / kg.

[0025] The inorganic contaminant content in the aged corn in the examples was lower than the limits specified in the National Feed Hygiene Standard (GB 13078-2017). Specifically, the total arsenic content was 0.45 mg / kg, lower than the standard limit of 2.0 mg / kg; the lead content was 1.20 mg / kg, lower than the standard limit of 10 mg / kg; the mercury content was 0.015 mg / kg, lower than the standard limit of 0.1 mg / kg; the cadmium content was 0.08 mg / kg, lower than the standard limit of 1 mg / kg; the fluorine content was 8.5 mg / kg, lower than the standard limit of 150 mg / kg; and the nitrite (calculated as NaNO2) content was 3.2 mg / kg, lower than the standard limit of 15 mg / kg.

[0026] Corn typically does not contain natural plant toxins. In the examples involving aged corn, the content of natural plant toxins was lower than the limits specified in the National Feed Hygiene Standard (GB 13078-2017). The cyanide (calculated as HCN) content was <2.0 mg / kg, lower than the standard limit of 50 mg / kg; free gossypol and isothiocyanates were not detected.

[0027] The examples involved aged corn with organochlorine contaminant content all below the limits specified in the National Feed Hygiene Standard (GB13078-2017). Specifically, polychlorinated biphenyls (PCBs) were <5.0 µg / kg, below the standard limit of 10 µg / kg; hexachlorocyclohexane (HCH) was <0.01 mg / kg, below the standard limit of 0.2 mg / kg; dichlorodiphenyltrichloroethane (DDT) was <0.01 mg / kg, below the standard limit of 0.05 mg / kg; and hexachlorobenzene (HCB) was <0.005 mg / kg, below the standard limit of 0.01 mg / kg.

[0028] The examples involved aged corn with microbial contaminant levels all below the limits specified in the national standard for feed hygiene (GB13078-2017). Specifically, the total mold count was 3.5 × 10⁻⁶. 4 CFU / g, below the standard limit of 4×10 4 CFU / g; Salmonella not detected.

[0029] The moisture content of both the aged corn and the regular corn involved in the examples was less than 13%.

[0030] The aged corn involved in the examples is corn with a fatty acid value >78mg / 100g, which is considered severely unsuitable for storage according to the "Rules for Judging the Storage Quality of Corn" (GB / T 20570-2015).

[0031] The kelp polysaccharide was purchased from Qingdao Mingyue Seaweed Bio-Health Technology Group. Its purity is 98%, and its sulfate content is 28.9%.

[0032] Animal experiments were conducted at the Acheng Experimental Base of Northeast Agricultural University from June to August 2023. These experiments were conducted with the approval of the Animal Committee of Northeast Agricultural University (approval number: NEAUEC20230243), and all procedures complied with the guidelines outlined in the "Animal Research Guidelines" of Northeast Agricultural University.

[0033] The instruments, equipment, reagents and materials not specified in the examples were all obtained through commercial means.

[0034] Example 1

[0035] Twenty-three healthy male Hu sheep with similar weights (39.05±3.55 kg) were selected for the experiment. A 10-week feeding trial was conducted. The first 14 days of the trial were designated as a pre-feeding period, during which the concentrate-to-roughage ratio of the Hu sheep's diet was gradually adjusted from 0:10 to 7:3. After the pre-feeding period, the sheep were randomly divided into three treatment groups based on their similar weights:

[0036] (1) Control group: aged corn replaced 0% of ordinary corn, NC group;

[0037] (2) Aged corn group: Aged corn 100% replaced ordinary corn, AC group;

[0038] (3) Aged corn + kelp polysaccharide group: 100% aged corn replaced ordinary corn + 0.5% kelp polysaccharide antioxidant based on dry matter, AC+LJP group.

[0039] Before the experiment began, the livestock sheds were thoroughly disinfected, and the sheep were dewormed. Morning feed was given at 7:00 AM and evening feed at 5:00 PM daily. During this time, roughage and concentrate were fed separately; roughage was given first, and concentrate was only given after the sheep had consumed all the roughage. Throughout the experiment, the sheep were housed in individual 1m x 2m pens, each with bedding that was changed every two days to maintain a clean environment. The composition and nutrient levels of the sheep's daily diet are shown in Table 1. The sheep were guaranteed free access to water daily during the experiment, and the daily surplus feed intake was ensured to be between 5% and 10% of the total feed intake.

[0040] Table 1. Composition and nutrient levels of the experimental basal diet (dry matter basis)

[0041]

[0042] Note: Each kilogram of compound premix contains 1500 IU of vitamin A, 200 IU of vitamin D, 15 IU of vitamin E, 75 mg of iron, 50 mg of copper, 40 mg of manganese, 50 mg of zinc, 0.5 mg of selenium, 1.0 mg of iodine, and 0.5 mg of cobalt; the nutritional levels are measured values.

[0043] During the formal trial period, the diet samples were collected every seven days and stored frozen at -20℃. After the trial, all diet samples were grouped and mixed. The diet samples were then dried at 65℃ for 48 hours, rehydrated for 24 hours, pulverized, and passed through a 1mm sieve. They were then sealed in airtight self-sealing bags for subsequent nutrient composition analysis.

[0044] Every morning at 7:00 AM, the amount of leftover feed from the previous day and the amount of feed input for the day were weighed and recorded for the Hu sheep. The daily feed intake for each Hu sheep was then calculated. On the 70th day of the experiment, the weight of each Hu sheep was weighed before the morning feed.

[0045] Feces from Hu sheep were collected at 7:00 and 19:00 on days 15-16, 40-41, and 66-68 of the experiment. The collected feces were then divided into two equal portions. One portion was treated with 10% concentrated sulfuric acid and stored at -20°C for later determination of CP content in the feces. The other portion was also stored at -20°C. After the experiment, the feces from the three stages were mixed, dried at 55°C for 48 hours, pulverized, and passed through a 1mm sieve. The mixture was then stored in sealed self-sealing bags for subsequent nutrient digestibility determination.

[0046] On the morning of the slaughter day, blood samples were collected from the jugular vein fossa of the sheep and placed into negative pressure heparin sodium tubes. The collected blood was centrifuged at 3000xg for 15 minutes, and the supernatant plasma was collected. The plasma was aliquoted into 1.5mL centrifuge tubes and stored at -20℃ for subsequent analysis of plasma biochemical and antioxidant indicators.

[0047] Immediately after slaughter, the rumen of the sheep was removed and its contents collected. The collected contents were immediately filtered through four layers of gauze to remove large feed particles, and the pH of the rumen fluid was immediately measured. Three 5 mL aliquots of the filtrate were collected. Two aliquots were added to 1 mL of 25% metaphosphate solution and 1 mL of 1% sulfuric acid solution, respectively, and frozen at -20°C for subsequent determination of NH3-N and volatile fatty acids (VFAs). The third aliquot was rapidly immersed in liquid nitrogen, transferred to the laboratory, and stored at -80°C for the determination of the rumen microbiota and metabolome. Additionally, one rumen fluid aliquot was placed in a 10 mL centrifuge tube and stored at -20°C for subsequent determination of MCP content.

[0048] Test

[0049] (I) Growth Performance Measurement: Based on the initial and final body weights and feed intake of the Hu sheep measured during the experimental period, the average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (F / G) of each group of Hu sheep were calculated. The effects of replacing ordinary corn with aged corn and adding kelp polysaccharides on the growth performance of Hu sheep are shown in Table 2:

[0050] Table 2. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the growth performance of Hu sheep.

[0051]

[0052] As shown in Table 2, the average daily weight gain of the sheep in group AC was significantly lower than that of the other groups (P<0.05); the feed conversion ratio was significantly higher than that of the other groups (P<0.05).

[0053] (II) Determination of dietary chemical composition and apparent digestibility of nutrients:

[0054] The dry matter and crude ash content of collected feed ingredients, finished products, and fecal samples were determined according to the analytical methods specified by AOAC. The contents of crude protein, crude fat, neutral detergent fiber, and acid detergent fiber were analyzed according to the method of Van Soest et al.

[0055] The fatty acid value (FAV) of the raw corn was determined according to the method specified in GB / T 20570-2015: 10g of sample was weighed and added to 50mL of anhydrous ethanol, extracted in a constant temperature air bath shaker for 30min, allowed to stand for 2min, and then filtered. A few drops of the initial filtrate were discarded, and 25mL was collected. 50mL of carbon dioxide-free distilled water was added, followed by the addition of phenolphthalein indicator. Finally, the volume of potassium hydroxide standard solution was recorded using an automatic titrator (Bethlehem Instruments Ltd., Zhejiang, China), and the mass of potassium hydroxide required to neutralize the free fatty acids in 100g of sample was calculated, which is the fatty acid value of the sample.

[0056] The content of acid insoluble ash (AIA) was determined according to the method specified in GB / T 23742-2009, "Determination of Hydrochloric Acid Insoluble Ash in Feed". The apparent digestibility of nutrients was determined using the AIA content in the diet and feces as internal standards, employing the endogenous indicator method to determine the apparent digestibility of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber. The formula for calculating the apparent digestibility of nutrients is as follows:

[0057] ;

[0058] in, The percentage of acid-insoluble ash in the diet. The percentage of acid-insoluble ash in feces. The percentage of a certain nutrient in the diet; This refers to the nutrient content in feces.

[0059] ① The physicochemical properties of aged corn and ordinary corn are shown in Table 3. Compared with ordinary corn, aged corn showed no significant differences in the content of conventional nutrients such as moisture, crude ash, crude fat, crude protein, neutral detergent fiber, and acid detergent fiber. The starch content of aged corn was slightly lower than that of ordinary corn, while its fatty acid value was much higher.

[0060] Table 3. Compositional analysis of aged corn and ordinary corn (dry matter basis %)

[0061]

[0062] ② The effects of replacing ordinary corn with aged corn and adding kelp polysaccharides on the apparent digestibility of Hu sheep are shown in Table 4. The apparent digestibility of crude protein, neutral detergent fiber, and acid detergent fiber in the AC group was significantly reduced (P<0.05). The apparent digestibility of crude protein, neutral detergent fiber, and acid detergent fiber in the NC group and the AC+LJP group was not significantly affected. The AC group showed a decreasing trend in apparent digestibility of dry matter (P=0.06).

[0063] Table 4. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on apparent nutrient digestibility.

[0064]

[0065] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0066] Analysis of tests (I) and (II) revealed that during storage, corn undergoes respiration, leading to a gradual decrease in antioxidant enzyme activity, lipid peroxidation, and a significant increase in ROS and malondialdehyde (MDA), the final product of lipid peroxidation. The reduced crude protein utilization indicates that oxidative stress affects the nitrogen utilization rate of Hu sheep, thus impacting rumen nitrogen metabolism. Simultaneously, the decreased digestibility of neutral and acid detergent fiber indicates that rumen microorganisms are affected in their digestion and decomposition, reducing the animal's absorption of nutrients and decreasing the body's energy supply. The tests found that aged corn significantly reduced the daily weight gain of Hu sheep and significantly increased the feed conversion ratio, indicating that replacing normal corn with aged corn reduces the growth performance of Hu sheep, consistent with previous research.

[0067] In the experiment, adding kelp polysaccharides to aged corn diets effectively alleviated the adverse effects of aged corn on the apparent digestibility of nutrients and growth performance in animals. This indicates that kelp polysaccharides, as a natural feed additive, can alleviate oxidative stress caused by aged corn and promote healthy animal growth.

[0068] (III) Meat quality determination

[0069] Approximately 150g of longissimus dorsi muscle from slaughtered Hu sheep was collected. Of this, 50g was used to determine the initial pH value and the pH value 24h after acid removal, as well as cooking loss, drip loss, shear force, brightness (L*), redness (a*), and yellowness (b*). The remaining 100g was frozen at -20℃ for the determination of antioxidant function and other indicators.

[0070] ① Meat pH value: Measured using a Statious-10 pH meter. Insert the electrode along the direction of the mutton muscle fibers. Start reading the pH value after the electrode is fully inserted into the sample and record the data after the pH reading stabilizes.

[0071] ② Cooking loss: Weigh an appropriate amount of meat sample, denoted as W1. Place the sample in a sealed bag and put it in an 80℃ water bath. Stop heating when the center temperature of the meat sample exceeds 70℃. Remove the meat sample, cool it to room temperature, and weigh it, denoted as W2. The formula for calculating cooking loss is as follows:

[0072] .

[0073] ③ Drip Loss: The obtained meat sample was trimmed into 2×2×2cm cubes and weighed, recorded as W1. The sample was then suspended in a sealable plastic box using fishing line and placed in a 4℃ refrigerator. After 24 hours, it was removed and weighed, recorded as W2. The formula for calculating drip loss is as follows:

[0074] .

[0075] ④ Shear force: After cooling, the sample with measured cooking loss was placed in a cone sampler to obtain a sample with a diameter of 2 cm and a height of 4 cm. The sample was measured using a digital tenderness meter along the direction perpendicular to the muscle fibers, and each sample was repeated 3 times.

[0076] ⑤ Take a 1cm thick meat sample and use a meat color analyzer to measure its brightness (L*), redness (a*), and yellowness (b*). Select 3 points that are not on the same straight line for measurement, and repeat the measurement 3 times at each point.

[0077] ⑥ Determination of Amino Acid Composition and Content in Muscle: After drying the meat sample in a freeze dryer, grind it and pass it through a 60-mesh sieve. Place 50 mg of the sample in a hydrolysis tube, add 6-8 mL of 1:1 (6 mol / L) HCl, purge the hydrolysis tube with nitrogen, seal it, and hydrolyze it in a 110℃ oven for 22 h. Remove, cool, shake well, filter, and dilute to 50 mL with double-distilled water. Rinse the hydrolysis tube at least 3 times. Take 1 mL of the filtrate and dry it in a freeze dryer (the solution needs to be frozen to a solid state before freeze-drying). After drying, add 1 mL of 0.02 mol / L HCl (1.8 mL HCl: 1000 mL H2O) to the tube and shake well. Centrifuge at 14000 rpm / min for 15 min, collect 0.8 mL of the supernatant, filter through a 0.45 μm filter membrane, and add it to a 1 mL glass sample bottle for later use. Use a fully automated amino acid analyzer to determine the amino acid composition and content.

[0078] ⑦ Determination of Antioxidant Properties of Muscle: An appropriate amount of meat sample was taken and its antioxidant properties were determined at 4℃. Using a commercial kit (Nanjing Jiancheng Bioengineering Institute), the total antioxidant capacity (T-AOC), GSH-Px, and superoxide dismutase (SOD) content of the muscle were determined by colorimetric methods. The absorbance of T-AOC was measured at 520 nm, the absorbance of GSH-Px at 412 nm, and the absorbance of SOD at 450 nm. The absorbance of catalase (CAT) in the muscle was measured using the ammonium molybdate method, and the absorbance of CAT was measured at 405 nm. The concentration of thiobarbituric acid reactants was determined using a commercial kit (Nanjing Jiancheng Bioengineering Institute), and the content of malondialdehyde (MDA) in the meat sample was determined, with its absorbance measured at 532 nm.

[0079] Results analysis:

[0080] (1) The effects of replacing ordinary corn with aged corn and adding kelp polysaccharide on the muscle quality of Hu sheep are shown in Table 5. The addition of aged corn significantly reduced meat color b* (P=0.054), while there were no significant differences in meat color L* and meat color a* among the groups (P>0.05). The muscle pH of the AC+LJP group was significantly higher than that of the control group and the AC group 45 minutes after slaughter (P=0.01), while there were no significant differences in muscle pH among the experimental groups after 24 hours (P>0.05). There were no significant differences in drip loss, cooking loss, and shear force among the groups (P>0.05).

[0081] Table 5. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the muscle quality of Hu sheep.

[0082]

[0083] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0084] (2) The effects of replacing ordinary corn with aged corn and adding kelp polysaccharide on the routine nutritional components of the longissimus dorsi muscle of Hu sheep are shown in Table 6. Compared with other experimental groups, the crude fat and crude protein in the AC group showed a decreasing trend, but the difference did not reach the level of statistical significance (P>0.05).

[0085] Table 6. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the routine nutritional components of Hu sheep muscle.

[0086]

[0087] (3) The effects of replacing ordinary corn with aged corn and adding kelp polysaccharide on the amino acid composition and content of Hu sheep muscle are shown in Table 7. A total of 17 amino acids were detected in Hu sheep muscle. The addition of aged corn caused a decrease in proline content in the muscle (P=0.06). The addition of kelp polysaccharide increased the proline content in the muscle that was affected by aged corn. The substitution of normal corn with aged corn had no significant effect on other amino acids in the muscle.

[0088] Table 7. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the amino acid composition and content of muscle in Hu sheep.

[0089]

[0090] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0091] (4) The effects of aged corn as a substitute for ordinary corn and the addition of kelp polysaccharides on the antioxidant index of Hu sheep muscle are shown in Table 8:

[0092] Table 8. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on antioxidant indices of Hu sheep muscle.

[0093]

[0094] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0095] Post-slaughter glycolysis in muscle accelerates, leading to the continuous accumulation of acidic substances such as phosphoric acid and lactic acid. This causes a rapid drop in pH, reducing the muscle's water-retention capacity, resulting in lighter meat color, decreased color stability, and negatively impacting tenderness. The addition of kelp polysaccharides resulted in a significantly higher pH at 45 minutes in the AC+LJP group compared to other experimental groups. This indicates that the addition of antioxidants may directly or indirectly inhibit the activity of glycogen phosphorylase, reducing the rate of glycogen breakdown and thus decreasing lactic acid production.

[0096] In meat color assessment, L*, a*, and b* are commonly used colorimetric indicators. L* represents brightness, a* represents red-green value, and b* represents yellow-blue value. Corn is an important source of carotenoids, which, after deposition in animal bodies, can affect the yellow hue (b* value) of fat and muscle. During long-term storage, aged corn may lead to the oxidative degradation of carotenoids, reducing their deposition in muscle. This resulted in a significant decrease in the b* value of muscle compared to the control group (P=0.05). The meat color b* value characterizes the degree of fat oxidation and pigment deposition, and its decrease is positively correlated with fat oxidation. While the addition of aged corn did not significantly affect meat color L* and a*, it did reduce their values. This suggests that aged corn may reduce the myoglobin content in muscle through oxidative stress, thus lightening the meat color.

[0097] Aged corn primarily affects muscle through oxidative stress. Therefore, indicators related to oxidative stress in muscle were measured to further evaluate the muscle damage caused by aged corn, as shown in Table 8. The addition of aged corn significantly reduced the GSH-Px and T-AOC contents in muscle compared to the control group (P<0.05). The addition of kelp polysaccharides significantly reduced the MDA content in muscle of the AC+LJP group compared to the other experimental groups (P<0.05). The unsaturated fatty acids in aged corn oxidize to produce hydroperoxides, malondialdehyde, and other products. Excessive accumulation of these substances in the sheep forces the GSH-Px enzyme system to work overtime to clear peroxides. The detoxification process of peroxide products also increases the burden on the liver, affecting its ability to synthesize GSH-Px and other enzymes, leading to a decrease in enzyme content in muscle.

[0098] Meanwhile, aged corn may affect rumen metabolic function, reducing the absorption efficiency of nutrients such as selenium and vitamin E. The decrease in T-AOC content also reflects the significant consumption of non-enzymatic antioxidants due to their role in combating lipid peroxidation products. Kelp polysaccharides are rich in active structures such as phenolic hydroxyl groups and sulfate groups, which can directly neutralize reactive oxygen ions and reduce the formation of lipid peroxidation products (such as MDA); simultaneously, the groups in the polysaccharides can chelate Fe... 2+ Cu 2+ Kelp polysaccharides inhibit the Fenton reaction catalyzed by metal ions, thereby reducing oxidative damage. They also reduce inflammation-related oxidative stress and indirectly decrease MDA production by inhibiting NF-κB-mediated inflammatory responses and reducing the release of pro-inflammatory factors. As a prebiotic, kelp polysaccharides may promote the proliferation of beneficial bacteria, inhibit endotoxin-producing bacteria, and reduce the entry of gut-derived oxidative stress factors into the bloodstream, thus indirectly reducing systemic oxidative damage.

[0099] Proline possesses the ability to scavenge free radicals and can directly neutralize reactive oxygen species (ROS) through its cyclic structure. Aged corn contains a large amount of oxygen free radicals; elevated intracellular ROS levels directly attack proteins, lipids, and DNA, disrupting cellular homeostasis. Under oxidative stress, muscle cells may consume large amounts of free proline to cope with free radical damage, leading to a decrease in proline content. Glutamate is a precursor to proline synthesis; the reduced glutamate content in the AC group of rumen differential metabolites also reflects insufficient glutamate supply after feeding aged corn to animals, resulting in limited proline synthesis. Kelp polysaccharides enhance the antioxidant function of muscle cells by increasing antioxidant enzyme activity and activating antioxidant pathways, preventing excessive consumption of free proline. Simultaneously, as a prebiotic, kelp polysaccharides can improve intestinal metabolic patterns, alleviate intestinal metabolic disorders caused by oxidative stress, and enhance the absorption efficiency of glutamate, vitamin C, and other proline synthesis precursors in the intestine.

[0100] (iv) Determination of plasma biochemical parameters: SOD, MDA, GSH-Px, T-AOC, and CAT in plasma were measured according to the standard procedure of the kit. Plasma samples were tested by Huaying Biotechnology Research Institute (Beijing, China) using a fully automated biochemical analyzer to determine total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBIL), direct bilirubin (DBIL), and alkaline phosphatase (ALP).

[0101] Table 9 shows the effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on plasma metabolites in Hu sheep.

[0102] Table 9. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on plasma metabolites in Hu sheep.

[0103]

[0104] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0105] The results showed that the MDA content in the plasma of Hu sheep in the AC group was significantly higher than that in other treatment groups (P<0.01), while the T-AOC content was significantly lower than that in other treatment groups (P<0.01). This indicates that feeding aged corn reduced the antioxidant capacity of Hu sheep and increased the risk of oxidative stress. The addition of kelp polysaccharides improved oxidative stress and antioxidant enzyme indicators, significantly increasing T-AOC and SOD levels and significantly decreasing MDA levels. This suggests that kelp polysaccharides have the ability to scavenge free radicals, can weaken the attack of lipid peroxidation products on cell membranes to a certain extent, reduce free radical damage to cells, indirectly stabilize the activity of antioxidant enzymes, leading to a decrease in MDA levels. Simultaneously, its active components may upregulate the expression of antioxidant enzyme genes by activating intracellular antioxidant signaling pathways, thereby increasing the activity of antioxidant enzymes in the blood.

[0106] The plasma AST level in the AC group was significantly higher than that in the NC group and the AC+LJP group (P<0.05). The DBIL levels in both the AC group and the AC+LJP group were significantly higher than those in the control group (P<0.05). The DBIL level in the AC+LJP group was lower than that in the AC group, but there was no significant difference.

[0107] AST is a marker of hepatocyte damage. During corn aging, lipid oxidation produces peroxidation products that can attack animal liver cells, damage hepatocyte membrane structures, and cause hepatocyte damage or apoptosis, leading to the release of AST into the bloodstream. Oxidized lipids may regulate the expression of lipid metabolism-related genes and inhibit the synthesis, transport, and excretion of bile acids by inhibiting the Farnesoid X receptor (FXR) signaling pathway. The accumulation of bile acids in the liver damages hepatocytes, impairs bilirubin metabolism, and ultimately leads to elevated DBIL levels.

[0108] (vi) Determination of liver antioxidant capacity:

[0109] After slaughter, the liver was quickly removed from the thoracic cavity and liver tissue samples were collected promptly. The collected liver tissue was rinsed with pre-cooled physiological saline to remove blood and other impurities, blotted dry with filter paper, and then rapidly frozen in liquid nitrogen. It was then transferred to a -80°C freezer for storage in preparation for subsequent antioxidant index testing. An appropriate amount of liver sample was taken and its antioxidant capacity was measured at 4°C. Using commercial reagent kits, the contents of T-AOC, GSH-Px, and SOD in the liver were determined colorimetrically. The absorbance of T-AOC was measured at 520 nm, GSH-Px at 412 nm, and SOD at 450 nm. The ammonium molybdate method was used to determine the CAT content in the liver, with the absorbance measured at 405 nm. The concentration of thiobarbituric acid reactants was determined using commercial reagent kits, and the MDA content in the liver samples was measured with its absorbance at 532 nm.

[0110] The effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the antioxidant indices of Hu sheep liver are shown in Table 10. The MDA content in the liver of the AC group showed an increasing trend compared to the other experimental groups, but the difference was not statistically significant (P>0.05). The addition of kelp polysaccharides significantly increased the T-AOC and CAT contents in the liver of the AC+LJP group compared to the other experimental groups (P<0.05).

[0111] Table 10. Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on antioxidant indices of Hu sheep liver.

[0112]

[0113] Note: NC = control group, aged corn 0% replaces ordinary corn; AC group = aged corn group, aged corn 100% replaces ordinary corn; AC+LJP group = aged corn + kelp polysaccharide group, aged corn 100% replaces ordinary corn + 0.5% kelp polysaccharide antioxidant.

[0114] No letter in the superscript of the same data indicates no significant difference (P>0.05), while different lowercase letters indicate significant differences (P≤0.05).

[0115] The liver plays a crucial role in nutrient breakdown, detoxification, and energy synthesis. As a metabolic hub, these processes (such as lipid metabolism) generate significant amounts of reactive oxygen species (ROS), making the liver one of the organs most severely affected by oxidative stress in the body. To cope with the high ROS environment, the liver has evolved a highly efficient endogenous antioxidant defense system, including enzyme systems, non-enzymatic antioxidants, and antioxidant functions in cellular structures. The liver may maintain its homeostasis by enhancing these efficient antioxidant systems. This may mask the potential effects of aged corn on the liver, possibly explaining why the increase in MDA content in the liver of the AC group in this experiment was not significant.

[0116] Kelp polysaccharides, due to their chemical structure, can bind to reactive oxygen species (ROS), directly neutralizing free radicals and reducing MDA content. Simultaneously, kelp polysaccharides may activate the Nrf2 signaling pathway, initiating the transcription of antioxidant response element genes, promoting the production of antioxidant enzymes such as CAT, and increasing liver T-AOC content. This resulted in a significant increase in T-AOC and CAT levels in the liver of the AC+LJP group in this experiment.

[0117] (VII) Determination of intestinal antioxidant properties: After slaughter, the intestines were removed and dissected according to their location. The intestines were rinsed with pre-cooled physiological saline to remove contents and impurities. After being blotted dry with filter paper, they were quickly frozen in liquid nitrogen and then stored at -80°C for subsequent antioxidant index testing. Appropriate amounts of ileum and colon samples were taken and their intestinal antioxidant properties were determined at 4°C. Using commercial kits, the contents of T-AOC, GSH-Px, and SOD in the ileum and colon were determined colorimetrically. The absorbance of T-AOC was measured at 520 nm, GSH-Px at 412 nm, and SOD at 450 nm. The concentration of thiobarbituric acid reactants was determined using commercial kits. The content of MDA in the intestinal samples was measured at 532 nm. The intestinal ROS content was determined using a fluorescent probe method using commercial kits.

[0118] Table 11 shows the effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the intestinal antioxidant index of Hu sheep.

[0119] Table 11 Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharides on the intestinal antioxidant indices of Hu sheep

[0120]

[0121] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0122] The results showed that the SOD content in both the AC group and the AC+LJP group was significantly higher than that in the NC group in both the ileum and colon (P<0.01), while the MDA content in both the AC+LJP group was significantly lower than that in the AC group in both the ileum and colon (P<0.05). The GSH-Px content in both the AC group and the control group was significantly higher than that in the AC group in both the ileum and colon (P<0.01), while the GSH-Px content in the AC+LJP group was significantly higher than that in the AC group in the ileum (P<0.01). The T-AOC content in both the AC group and the control group was significantly higher than that in the AC group in both the ileum and colon (P<0.01), while the T-AOC content in the AC+LJP group was significantly higher than that in the AC group in both the ileum and colon (P<0.01). The ROS content in both the AC group and the AC group was significantly higher than that in all other groups in both the ileum and colon (P<0.01).

[0123] During the aging process, corn undergoes lipid peroxidation, generating large amounts of reactive oxygen species (ROS) and the peroxide end product maize (MDA). Feeding corn to animals as diet leads to the direct attack of peroxidized fatty acids on intestinal cells, triggering cell membrane lipid peroxidation and causing MDA accumulation, thus increasing the levels of ROS and MDA in the animal's body. This explains why the ROS and MDA levels in the ileum and colon of the AC group were significantly higher than those in the NC group in this experiment.

[0124] Increased ROS levels in animals activated the Nrf2 / ARE signaling pathway, promoting the synthesis of antioxidant enzymes such as SOD and GSH-Px, and increasing T-AOC. The simultaneous increase in antioxidant and oxidative indices in the ileum and colon of the AC group in this experiment may be due to insufficient compensatory increases in the antioxidant system to completely neutralize the excessive ROS introduced by the aged corn, leading to persistent oxidative damage in the intestines. With prolonged experimental duration, extended exposure to peroxidation may deplete the body's antioxidant resources and exacerbate oxidative damage.

[0125] Kelp polysaccharides are rich in sulfate groups and phenolic substances, which can directly neutralize reactive oxygen species, block oxidative chain reactions, and reduce lipid peroxidation products. Kelp polysaccharides may also regulate the Nrf2 / ARE antioxidant pathway by targeting and activating the Nrf2 transcription factor, promoting the synthesis of antioxidant enzymes such as SOD and GSH-Px. Furthermore, as a prebiotic, kelp polysaccharides can promote the proliferation of beneficial bacteria in the gut, improve gut microbiota structure, inhibit harmful bacteria, and reduce intestinal oxidative stressors.

[0126] (viii) Determination of rumen fermentation indicators:

[0127] ① The pH value of the rumen fluid after filtration through four layers of gauze was measured using a portable pH meter.

[0128] ②The determination of NH3-N was performed using the indophenol colorimetric method: The sample was centrifuged at 12000g for 20 min, and the supernatant was retained. 40 μL of the supernatant was transferred to a test tube, followed by the addition of 2.5 mL of phenol solution and 2 mL of sodium hypochlorite solution. After mixing thoroughly, the mixture was incubated in a water bath at 37℃ for 30 min, and then cooled with cold water to terminate the reaction. The absorbance was measured at a wavelength of 550 nm using a spectrophotometer.

[0129] ③VFAs were determined by gas chromatography using a Shimadzu GC-2010 gas chromatograph equipped with an Agilent capillary column. Standard solutions of volatile fatty acids at different concentrations were prepared, and the content of volatile fatty acids in rumen fluid was determined using a standard curve method. The standard curve reagents included acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, and valeric acid. The samples were centrifuged at 10000g for 15 min, filtered through an aqueous filter membrane, and then sealed and stored at 4℃ for gas chromatographic analysis. The operating parameters of the gas chromatograph were as follows: injection port and detector temperature set to 220℃; initial temperature 120℃, held for 3 min, then increased to 180℃ at a rate of 10℃ / min; high-purity nitrogen as carrier gas; injection pressure 90 kPa; hydrogen flow rate 40 mL / min; air flow rate 400 mL / min; and make-up gas flow rate 45 mL / min.

[0130] ④ Rumen Microbial Protein (MCP) Determination: After lyophilizing the rumen fluid sample, accurately weigh 0.2 g of the lyophilized sample into a 15 mL centrifuge tube; add 10 mL of 19.4% trichloroacetic acid (TCA) solution to each tube (TCA is added in four equal increments of 2.5 mL to minimize foaming), and then incubate on ice for 45 min. Quantitatively transfer the contents of the tube to a 50 mL centrifuge tube (carefully rinse the tube with a minimum amount of 2% TCA), and centrifuge at 7719 g for 20 min; quantitatively transfer the contents of each centrifuge tube to a single Whatman 541 filter paper and filter by gravity, rinsing the residue with 2% TCA until all the contents are rinsed into the filter paper; then filter the filtrate through a Whatman GF / A glass fiber filter, rinsing the residue with 2% TCA; dry the Whatman 541 and GF / A filters at 55 °C for 24 h; place the dried Whatman 541 and GF / A filters into the same protein tube for Kjeldahl nitrogen determination.

[0131] Table 12 shows the effects of replacing regular corn with aged corn and adding kelp polysaccharides on rumen fermentation in Hu sheep.

[0132] Table 12 Effects of aged corn as a substitute for regular corn and the addition of kelp polysaccharide on rumen fermentation in Hu sheep

[0133]

[0134] Note: No letter in the superscript of the same row indicates no significant difference (P>0.05), different lowercase letters indicate significant difference (P≤0.05).

[0135] After consuming food, animals produce a large amount of organic acids through the action of rumen microorganisms, leading to fluctuations in rumen pH. When the rumen environment stabilizes, the pH value is typically between 5.5 and 7.0. In this experiment, the rumen pH values ​​of all groups were within the normal range, and there were no significant changes in pH values ​​among the experimental groups. The lack of significant pH changes in this experiment may be due to the relatively strong or short-lived impact of aged corn on the Hu sheep, or it may be related to compensatory mechanisms from other physiological regulatory mechanisms in the Hu sheep. Prolonged low rumen pH levels can trigger a series of physiological and metabolic abnormalities, including rumen microbial imbalance, impaired nutrient absorption, and disordered immune responses, resulting in decreased productivity and adverse health consequences for ruminants.

[0136] NH3-N concentration directly reflects the nitrogen utilization rate of rumen microorganisms and is the most important nitrogen source for ruminants. The vast majority of rumen microorganisms utilize NH3-N as a nitrogen source to synthesize mechanoprotein (MCP), which can meet 40%-80% of the protein requirements of ruminants. A decrease in rumen NH3-N concentration affects the types, quantity, and activity of rumen microorganisms, leading to reduced microbial protein synthesis, altering rumen microbial fermentation patterns and efficiency, changing the production and proportion of volatile fatty acids, and ultimately impacting the energy supply of ruminants.

[0137] VFAs are the main byproducts of carbohydrate degradation in the rumen, serving as the primary source of metabolic energy for rumen fermentation in ruminants. Their main components are acetic acid, propionic acid, and butyric acid, all precursors for energy production in ruminants. Various physiological functions of the rumen are regulated by these short-chain fatty acids. Appropriate concentrations of short-chain fatty acids can promote rumen wall microbial diversity and enrich its gene pool, induce a symbiotic lifestyle of opportunistic pathogens, suppress inappropriate immune responses, and promote tight junctions and cell renewal in the rumen epithelium. However, further changes in short-chain fatty acid concentration can lead to rumen acidification, reduced rumen wall microbial diversity, upregulation of immune responses, disruption of tight junctions and gap junctions in the rumen epithelium, and impairment of epithelial homeostasis.

[0138] In this experiment, the NH3-N and MCP contents of the aged corn group were significantly lower than those of the other two groups (P<0.05), and the total VFA, acetic acid, and butyric acid contents were significantly lower than those of the other experimental groups (P<0.05). The propionic acid content showed a decreasing trend compared to the other two groups (P=0.05). This indicates that feeding aged corn affected the rumen fermentation pattern of Hu sheep. With prolonged storage, the starch structure of corn undergoes significant changes, with an increase in amylose content, which is conducive to the formation of resistant starch. This reduces the available energy. The growth, reproduction, and fermentation of rumen microorganisms require a sufficient energy supply; insufficient energy will limit the metabolic activities of microorganisms, leading to a decrease in the production of volatile fatty acids and microbial proteins.

[0139] Furthermore, with the aging of corn, the content of anti-nutritional factors such as non-starch polysaccharides may increase. Non-starch polysaccharides are difficult for rumen microorganisms to degrade, encapsulating nutrients such as starch, reducing their contact area with microorganisms, hindering digestion and fermentation processes, and leading to a decrease in the production of ammonia nitrogen, volatile fatty acids, and microbial protein. In this experiment, the addition of kelp polysaccharides improved the rumen fermentation pattern of sheep fed an aged corn diet, restoring the rumen environment affected by aged corn to a level similar to that of sheep fed a normal diet. This may be because kelp polysaccharides are polysaccharides that provide additional carbon and energy sources for rumen microorganisms. In addition, kelp polysaccharides also contain trace elements such as iodine, potassium, and magnesium, which can participate in various metabolic reactions in the rumen and indirectly promote rumen fermentation. As a prebiotic, kelp polysaccharides have certain spatial structures and chemical properties, which can stabilize enzyme structures, improve enzyme activity, promote the growth of beneficial bacteria, and optimize the microbial community structure in the rumen environment.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A ruminant feed based on aged corn and kelp polysaccharides, characterized in that, The ordinary corn in the ruminant feed is replaced with aged corn in equal proportion and 0.5% kelp polysaccharide is added on a dry matter basis. The aged corn is ordinary corn that has been stored for 4 years and meets the feed hygiene standards. The ruminant is the Hu sheep.

2. The ruminant feed based on aged corn and kelp polysaccharides according to claim 1, characterized in that, The ruminant feed, on a dry matter basis, contains the following raw materials in the following percentages by weight: 30% sheepgrass, 32.76% aged corn, 14% sprayed corn husk, 3.5% corn germ meal, 10.5% DDGS, 5.6% soybean meal, 0.7% beet molasses, 1.05% limestone powder, 0.42% slow-release ammonium chloride, 0.42% sodium chloride, 0.42% dicalcium phosphate, 0.35% sodium bisulfate, 0.28% compound premix, and 0.5% kelp polysaccharide.

3. A ruminant feed based on aged corn and kelp polysaccharides according to claim 1, characterized in that, The kelp polysaccharide has a purity of ≥98% and a sulfate content of ≥28%.

4. A ruminant feed based on aged corn and kelp polysaccharides according to claim 1, characterized in that, The moisture content of both the ordinary corn and the aged corn was less than 13%.

5. The application of a ruminant feed based on aged corn and kelp polysaccharides as described in any one of claims 1 to 4 in improving the production performance, meat quality, liver antioxidant properties, and intestinal antioxidant properties of ruminants.

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