Compound microbial inoculant for improving fiber utilization of broiler chickens and application thereof

Abstract

The application discloses a compound microbial agent for improving fiber utilization of broilers and application thereof, and belongs to the technical field of microorganisms. The compound microbial agent is compounded by Lactobacillus casei R7-6 and Lactobacillus rhamnosus R5-8 at a volume ratio of 1:0.5-2. The two known strains are compounded for the first time, and it is found that the compounded strains have a synergistic effect within the range of 1:0.5-2, and the effect is significantly reduced beyond the range. The compound microbial agent has selective fermentation characteristics for different fiber source substrates, and the fermentation effect of the compound microbial agent on purple elephant grass and Guimin elephant grass is significantly better than that on alfalfa and Gegen. After fermentation, the content of crude protein is increased, and the content of neutral detergent fiber is reduced. When the compound microbial agent is used for feeding the purple elephant grass or the Guimin elephant grass, the daily average weight gain of broilers is increased, the feed conversion ratio is reduced, and the abdominal fat rate is reduced. The application provides an efficient microbial solution for high-value utilization of agricultural by-products such as purple elephant grass, Guimin elephant grass and other fibers.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to the application of compound microbial agents in the preparation of fermented feed that improves broiler fiber utilization and enhances broiler production and slaughter performance. Background Technology

[0002] Dietary fiber is an indispensable component of poultry feed. Adequate fiber can promote gastrointestinal digestion and benefit gut health. However, as monogastric animals, poultry lack the enzymes to break down fiber in their stomach and small intestine, relying solely on microorganisms in the large intestine for limited fiber breakdown. Therefore, their adaptability to crude fiber is limited. Existing research indicates that while adding different types of fiber sources (such as elephant grass, alfalfa, and kudzu) to broiler diets can provide some gut health benefits, it often significantly reduces broiler growth performance. For example, studies have reported that adding fermented purple elephant grass, *Guimin* elephant grass, alfalfa, or kudzu can significantly reduce the average daily weight gain and significantly increase the feed conversion ratio in broilers, also affecting slaughter performance to varying degrees.

[0003] Microbial fermentation of fibrous feed ingredients is considered an effective way to enhance their nutritional value and improve animal growth performance. However, fibrous substrates from different sources exhibit significant differences in their lignocellulose structure, soluble sugar content, and anti-nutritional factors, leading to potentially drastically different fermentation effects and nutritional improvements on different fibrous substrates using the same microbial agent.

[0004] Therefore, the targeted optimization of fermentation effects by screening or compounding specific microbial agents for specific fiber sources is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of the above, the purpose of this invention is to provide a compound microbial agent composed of known strains Lactobacillus casei R7-6 and Lactobacillus rhamnosus R5-8. It has been found that the compound microbial agent has significant differences in fermentation effect on different fiber source substrates, and is particularly suitable for the fermentation treatment of purple elephant grass and Guimin elephant grass. It can effectively improve the utilization efficiency of fiber feed by broilers and overcome the problem of decreased growth performance of broilers due to feeding fiber source feed in the prior art.

[0006] To achieve the above objectives,

[0007] This invention provides a compound microbial agent for improving fiber utilization in broilers, characterized in that the compound microbial agent comprises Lactobacillus rhamnosus (… Lactobacillus rhamnosus R5-8 strain and Lactobacillus casei ( Lactobacillus casei R7-6 strain,

[0008] The Lactobacillus rhamnosus ( Lactobacillus rhamnosusThe accession number for R5-8 is CCTCC NO:2018436, and the accession date is July 2, 2018; the Lactobacillus casei ( Lactobacillus casei The accession number of R7-6 is CCTCC NO:M2018435, and the accession date is July 2, 2018.

[0009] To further explain, the compound microbial agent is composed of Lactobacillus rhamnosus ( Lactobacillus rhamnosus R5-8 and Lactobacillus casei ( Lactobacillus casei R7-6 was prepared by mixing them at a volume ratio of 1:0.5~2.

[0010] Preferably, the compound microbial agent is composed of Lactobacillus rhamnosus (Lactobacillus rhamnosus). Lactobacillus rhamnosus R5-8 and Lactobacillus casei ( Lactobacillus casei R7-6 was prepared by mixing them at a volume ratio of 1:1.

[0011] The present invention also provides the application of the aforementioned compound microbial agent in the preparation of elephant grass fermented feed.

[0012] To further clarify, the raw materials for the fermented elephant grass feed are purple elephant grass and / or Guimin elephant grass.

[0013] The present invention also provides a fermented feed containing the above-mentioned compound microbial agent. The preparation method of the fermented feed is as follows: crush purple elephant grass and / or Guimin elephant grass, adjust the moisture content to 40-60%, inoculate with Lactobacillus casei strain R7-6 or Lactobacillus rhamnosus strain R5-8 or compound microbial agent, inoculate into purple elephant grass and / or Guimin elephant grass at an inoculation rate of 100 ml / kg, mix evenly, and then seal for fermentation.

[0014] The present invention also provides the application of the fermented feed as described above in feeding broiler chickens.

[0015] To further clarify, the broiler chicken in question is the Jinling Flower Chicken.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. This invention is the first to combine Lactobacillus casei R7-6 and Lactobacillus rhamnosus R5-8 to form a compound bacterial agent. Experiments have shown that the fermentation effect of the two strains on fiber substrates is significantly better than that of a single strain, with the crude protein content increasing by about 14% to 18% and the neutral detergent fiber degradation rate increasing by 6.5% to 7.9%, demonstrating a clear synergistic effect.

[0018] 2. Through systematic ratio screening experiments, this invention determined the optimal mixing ratio of *Lactobacillus casei* R7-6 to *Lactobacillus rhamnosus* R5-8 to be 1:0.5~2, with the most preferred ratio being 1:1. Experiments confirmed that when the mixing ratio exceeds this range, the synergistic effect significantly weakens, and the fermentation effect drops back to near the level of a single strain, indicating that the mixing ratio range of this invention is critical and irreplaceable.

[0019] 3. Through research, the inventors discovered that the compound microbial agent exhibits significant differences in fermentation effects on different fiber-source substrates. When applied to purple elephant grass and Guimin elephant grass, it can significantly reduce the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF) in the feed and increase the crude protein (CP) content, with effects significantly superior to those on alfalfa and kudzu.

[0020] 4. Broilers fed with purple elephant grass or Guimin elephant grass fermented with the compound microbial agent of this invention showed a significant increase in average daily weight gain and a significant decrease in feed conversion ratio, effectively overcoming the technical problem of declining broiler growth performance caused by traditional fiber-rich feeds. Simultaneously, it also optimized the slaughter performance of broilers, such as significantly reducing abdominal fat percentage.

[0021] 5. This invention provides a highly efficient and specialized microbial solution for the high-value utilization of fibrous agricultural by-products such as purple elephant grass and Guimin elephant grass, which helps to reduce broiler breeding costs and improve economic benefits. Attached Figure Description

[0022] Figure 1 This is a comparative graph showing the effects of the compound microbial agent of the present invention fermentation on different fiber source substrates on the average daily weight gain of broilers.

[0023] Figure 2 This is a comparative graph showing the effects of fermentation of different fiber-source substrates by the compound microbial agent of the present invention on the feed conversion ratio of broilers.

[0024] Figure 3 This is a comparative graph showing the effects of the compound microbial agent of the present invention fermentation on different fiber source substrates on abdominal fat percentage in broilers.

[0025] Information on the preservation of biological materials

[0026] The strain information deposited in this application is as follows:

[0027] Lactobacillus rhamnosus R5-8, its classification name is: Lactobacillus rhamnosus R5-8, Chinese classification name: Lactobacillus rhamnosus R5-8, accession number CCTCC NO:2018436; this strain is deposited at China Center for Type Culture Collection, Wuhan University, Wuhan, China, July 2, 2018.

[0028] Lactobacillus casei R7-6, its classification name is: Lactobacillus caseiR7-6, Chinese classification name: Lactobacillus casei R7-6, accession number CCTCC NO:M2018435; this strain is deposited at China Center for Type Culture Collection, Wuhan University, Wuhan, China, July 2, 2018. Detailed Implementation

[0029] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0030] Unless otherwise stated, each feature disclosed in this specification (including any appended claims and abstract) is merely one example of a series of equivalent or similar features.

[0031] Example 1: Preparation of Compound Microbial Agent

[0032] Lactobacillus casei R7-6 (CCTCC M 2018435) and Lactobacillus rhamnosus R5-8 (CCTCC M 2018436) were inoculated into MRS liquid medium and activated by incubation at 37°C for 24 h. After activation, the bacterial cells were collected and the bacterial concentration was adjusted to 10⁻⁶ with sterile physiological saline. 8 CFU / mL. The two bacterial solutions were mixed at a volume ratio of 1:1 to obtain a compound bacterial agent.

[0033] Example 2: Comparison of fermentation effects between compound microbial agents and single strains

[0034] This embodiment is used to verify the synergistic effect of the compound microbial agent (R7-6+R5-8) of the present invention compared with a single strain (R7-6 or R5-8) in fermenting fiber substrates.

[0035] 1.1 Preparation of Fermented Feed

[0036] Using *Elephantgrass* from Guangxi and Fujian as the fermentation substrate, it was pulverized and the moisture content was adjusted to 50%. The following treatment groups were set up:

[0037] 1.2 Experimental Design:

[0038] Control group (CK): No bacterial agent added.

[0039] Single bacterial group 1 (R7-6): Inoculate with Lactobacillus casei R7-6 bacterial suspension at an inoculation rate of 100 mL / kg.

[0040] Single bacterial group 2 (R5-8): Inoculate with Lactobacillus rhamnosus R5-8 bacterial suspension at an inoculation rate of 100 mL / kg.

[0041] Compound bacterial group (R7-6+R5-8): The compound bacterial agent prepared in Example 1 was inoculated at an inoculation rate of 100 mL / kg.

[0042] After thorough mixing, the mixtures were placed in polyethylene bags equipped with one-way exhaust valves, vacuum-sealed, and fermented at room temperature in the dark for 28 days. Crude protein (CP) and neutral detergent fiber (NDF) content were measured after fermentation. Three replicates were set for each group, and data are expressed as mean ± standard deviation. Results are shown in Table 1.

[0043] Table 1. Comparison of the effects of different microbial agents on fermenting *Elephant Ear Grass* in Guangxi and Fujian.

[0044]

[0045] Note: Different superscript letters in the same column indicate significant differences (P<0.05).

[0046] The results showed that, compared with the unfermented control (CK), all inoculant treatments significantly increased CP content and decreased NDF content. Specifically, the CP content of the compound inoculant group (R7-6+R5-8) was approximately 57.7% higher than CK, approximately 14.1% higher than R7-6, and approximately 18.2% higher than R5-8; the NDF content of the compound inoculant group was approximately 23.2% lower than CK, approximately 6.5% lower than R7-6, and approximately 7.9% lower than R5-8. When treated with the two single strains alone, the CP increases were 38.2% (R7-6) and 33.5% (R5-8), respectively, while the NDF decreases were 17.9% (R7-6) and 16.7% (R5-8), respectively. The improvement effect of the compound bacterial group was significantly better than that of any single strain group (P<0.05), and the effect of the two strains combined was far greater than that of either strain alone, indicating that Lactobacillus casei R7-6 and Lactobacillus rhamnosus R5-8 produced a synergistic effect when fermenting Elephantgrass in Guimin.

[0047] Example 3: Effect of different compound microbial agent ratios on fermentation effect

[0048] This embodiment is used to verify the effect of the compound ratio of Lactobacillus casei R7-6 and Lactobacillus rhamnosus R5-8 on the fermentation effect of fiber substrate, so as to determine the optimal compound ratio range.

[0049] 1.1 Experimental Design

[0050] Using *Lactobacillus casei* from the Guangxi and Fujian regions as the fermentation substrate, the substrate was pulverized and its moisture content adjusted to 50%. *Lactobacillus casei* R7-6 and *Lactobacillus rhamnosus* R5-8 were activated separately, and the bacterial concentration was adjusted to 10. 8 CFU / mL. The two bacterial cultures were mixed at different volume ratios to create the following treatment groups:

[0051] Control group (CK): No bacterial agent added.

[0052] Single bacterial group (R7-6): only Lactobacillus casei R7-6 bacterial suspension was added.

[0053] Single bacterial group (R5-8): only Lactobacillus rhamnosus R5-8 bacterial suspension was added.

[0054] Ratio 1: R7-6: R5-8 = 1: 0.3.

[0055] Ratio 2: R7-6: R5-8 = 1: 0.8.

[0056] Ratio 3: R7-6: R5-8 = 1:1.

[0057] Ratio 4: R7-6: R5-8 = 1: 1.5.

[0058] Ratio 5: R7-6: R5-8 = 1:2.

[0059] Ratio 6: R7-6: R5-8 = 1:3.

[0060] Each treatment group was inoculated with the corresponding bacterial culture or mixed bacterial culture at an inoculation rate of 100 mL / kg. After thorough mixing, the cultures were placed in polyethylene bags equipped with one-way exhaust valves, vacuum sealed, and fermented at room temperature in the dark for 28 days. After fermentation, the contents of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were measured. Each group was tested in triplicate, and data are expressed as mean ± standard deviation.

[0061] 1.2 Experimental Results

[0062] The results are shown in Table 2.

[0063] Table 2 Comparison of the effects of fermented *Elephant Ear Grass* from Guangxi and Fujian with different compound ratios

[0064]

[0065] Note: Different superscript letters in the same column indicate significant differences (P<0.05).

[0066] 1.3 Results Analysis

[0067] As shown in Table 2:

[0068] Ratio 1 (1:0.3): This ratio is lower than the scope of protection claimed in this invention (1:0.5~2). Its CP content (11.23%) was slightly higher than the single-strain group (R7-6 10.82%, R5-8 10.45%) and ratio 6 (10.96%), but there was no significant difference (P>0.05). However, it was significantly lower than the ratios 2~5 (12.08%~12.35%) (P<0.05). Its NDF and ADF contents were not significantly different from the single-strain group, but significantly higher than the ratios 2~5 (P<0.05). This indicates that when the proportion of *Lactobacillus rhamnosus* R5-8 is too low, the synergistic effect of the two strains cannot be fully utilized, and the improvement in fermentation effect is limited.

[0069] Ratios 2–5 (1:0.8, 1:1, 1:1.5, 1:2): These four ratios are all within the protection range required by our research group. Compared with the single-strain group and ratios 1 and 6, the CP content was significantly increased (P<0.05), while the NDF and ADF contents were significantly decreased (P<0.05). Among them, ratio 3 (1:1) showed the best effect, with a CP content of 12.35%, significantly higher than other treatment groups (P<0.05), an NDF content (48.97%) significantly lower than all other treatment groups (P<0.05), and an ADF content (40.28%) that was not significantly different from ratios 2, 4, and 5 but significantly lower than the single-strain group and ratios 1 and 6 (P<0.05).

[0070] Ratio 6 (1:3): This ratio exceeds the scope of protection claimed in this invention. Its CP content (10.96%) was not significantly different from that of ratio 1 (P>0.05), but significantly lower than that of ratios 2-5 (P<0.05); its NDF and ADF contents were not significantly different from those of the single-strain group and ratio 1, but significantly higher than those of ratios 2-5 (P<0.05). This indicates that when the proportion of *Lactobacillus rhamnosus* R5-8 is too high, the proportion of *Lactobacillus casei* R7-6 is relatively insufficient, which may lead to microbial imbalance and inhibit synergistic fermentation.

[0071] In summary, the ratio of *Lactobacillus casei* R7-6 to *Lactobacillus rhamnosus* R5-8 significantly affected the fermentation effect (P<0.05). When the ratio was within the range of 1:0.8 to 2, the fermentation effect was significantly better than that of a single strain. When the ratio exceeded the range of 1:0.5 to 2 (i.e., 1:0.3 in ratio 1 and 1:3 in ratio 6), the fermentation effect decreased significantly, showing no significant difference from the single strain group (P>0.05). Therefore, the optimal ratio range of the compound microbial agent described in this invention is 1:0.5 to 2, with 1:1 being the most preferred.

[0072] Example 4: Comparison of fermentation effects of compound microbial agents on different fiber-derived substrates

[0073] This embodiment is used to verify that the fermentation effect of the compound microbial agent of the present invention on different fiber source substrates (purple elephant grass, Guangxi elephant grass, alfalfa, and kudzu) is significantly different.

[0074] 1.1 Preparation of Fermented Feed

[0075] Purple elephant grass, *Elephant grass from Fujian and Guizhou*, alfalfa, and kudzu were used as fermentation substrates, respectively. The substrates were pulverized and their moisture content adjusted to 50%. Each substrate was inoculated with the compound microbial agent prepared in Example 1 at a rate of 100 mL / kg. After thorough mixing, the mixture was placed in polyethylene bags equipped with one-way exhaust valves, vacuum-sealed, and fermented at room temperature in the dark for 28 days. Simultaneously, a non-fermented control was set up for each substrate: the same pulverized and moisture-content-adjusted substrates were taken, but not inoculated with the compound microbial agent, directly vacuum-sealed, and stored at 4°C for later use.

[0076] After fermentation, the contents of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in each fermentation group and the corresponding unfermented control group were measured. Each group had three replicates, and data are expressed as mean ± standard deviation. Paired t-tests were used to compare differences before and after fermentation of the same substrate, and one-way ANOVA and Tukey HSD post-hoc tests were used to compare differences between groups after fermentation of different substrates. A significance level was set at P < 0.05. The results are shown in Table 3.

[0077] Table 3 Comparison of nutrient composition before and after fermentation of different fiber-source substrates with compound microbial agents

[0078]

[0079] Note: The above indicates that the difference between fermented and unfermented control is significant (paired t-test, P<0.05); different superscript letters on the data after fermentation in the same column indicate significant differences between different substrates (ANOVA, P<0.05).

[0080] The results showed that after fermentation using the compound microbial agent of this invention, the CP content of all substrates was significantly increased compared with their respective unfermented controls (P<0.05), while the NDF and ADF contents were significantly decreased compared with their respective unfermented controls (P<0.05). However, the magnitude of change varied significantly among different substrates: when using purple elephant grass and *Eriocaulon guiminensis* as substrates, CP increased by approximately 74.2% and 57.7%, respectively; NDF decreased by approximately 25.9% and 23.2%, respectively; and ADF decreased by approximately 25.3% and 22.4%, respectively. When using alfalfa and kudzu as substrates, CP increased by only approximately 6.7% and 9.4%, respectively; NDF decreased by approximately 5.4% and 7.0%; and ADF decreased by approximately 6.3% and 8.0%, respectively. In absolute terms after fermentation, the CP content of alfalfa and kudzu was significantly higher than that of purple elephant grass and *Eriocaulon guiminensis* (P<0.05), but their NDF and ADF contents were also significantly lower (P<0.05), which is related to their inherently higher nutritional quality. However, in terms of the magnitude of increase (decrease), the increase in CP and the decrease in NDF and ADF after fermentation of purple elephant grass and Guimin elephant grass were significantly greater than those of alfalfa and kudzu (P<0.05), indicating that the compound microbial agent of the present invention has a significantly better fermentation effect on purple elephant grass and Guimin elephant grass than on alfalfa and kudzu.

[0081] Example 5: Effects of different fermentation substrates on broiler production performance

[0082] This embodiment is used to verify the effect of using the compound microbial agent of the present invention to ferment and treat different fiber source feeds on improving the production performance of broilers, and to further confirm the superiority of using purple elephant grass and Guimin elephant grass as substrates.

[0083] 1.1 Preparation of Fermented Feed

[0084] Following the method in Example 4, fermented purple elephant grass, fermented Guimin elephant grass, fermented alfalfa, and fermented kudzu were prepared respectively.

[0085] 1.2 Experimental Animals and Design

[0086] Two hundred and forty healthy Jinling Flower Chickens aged 30 days with no significant weight difference were randomly divided into five treatment groups, with 48 birds in each group and four birds per cage. The rearing environment was well-ventilated, with natural lighting, and humidity maintained at approximately 55%. Birds had free access to feed and water, and were fed twice daily. The trial lasted 15 weeks. Basic feed was provided by Guangxi Dafuhua Agricultural and Livestock Feed Co., Ltd.; the Jinling Flower Chickens were provided by Guangxi Jinling Agricultural and Livestock Co., Ltd.

[0087] Control group (CK): fed with basal diet.

[0088] Experimental Group 1 (GG): Basal diet + 8% fermented purple elephant grass.

[0089] Experimental group 2 (GR): basal diet + 8% fermented Guimin elephant grass.

[0090] Experimental group 3 (LM): basal diet + 8% fermented alfalfa.

[0091] Experimental group 4 (LA): basal diet + 8% fermented kudzu.

[0092] Each group recorded its daily feed intake and uneaten feed. At the end of the experiment, the group was weighed on an empty stomach, and growth performance indicators such as average daily weight gain and feed conversion ratio were calculated.

[0093] 1.3 Test Results

[0094] The results are shown in Table 4. Figure 1-2 As shown in the figure, compared with the control group, broilers fed with purple elephant grass (GG group) and Guimin elephant grass (GR group) fermented with the compound microbial agent of this invention had significantly higher average daily weight gain (P<0.05) and significantly lower feed conversion ratio (P<0.05) than the control group. However, broilers fed with fermented alfalfa (LM group) and fermented kudzu (LA group) showed no significant difference in average daily weight gain compared with the control group, but their feed conversion ratio was slightly higher. This indicates that the fermentation effect of the compound microbial agent of this invention on purple elephant grass and Guimin elephant grass can effectively translate into improved broiler production performance, overcoming the problem of decreased growth performance caused by traditional fiber-rich feeds.

[0095] Table 4. Effects of different fermentation substrates on the production performance of Jinling Flower Chicken

[0096]

[0097] Note: This indicates a significant difference compared to the control group (P<0.05).

[0098] Example 6: Effects of different fermentation substrates on broiler slaughter performance

[0099] At the end of the experiment in Example 5, 12 broilers of similar weight were randomly selected from each treatment group for slaughter, and slaughter performance indicators were measured. The results are shown in Table 5. Figure 3 As shown in the figure, compared with the control group, the abdominal fat percentage of the GG and GR groups was significantly reduced (P<0.05), while other slaughter performance indicators (slaughter rate, eviscerated yield, etc.) showed no significant differences. The slaughter performance indicators of the LM and LA groups showed no significant differences compared with the control group. The results indicate that fermenting *Eriocheir sinensis* and *Eriocheir sinensis var. sinensis* with the compound microbial agent of this invention can significantly reduce abdominal fat percentage and improve meat quality without affecting broiler meat production performance.

[0100] Table 5. Effects of different fermentation substrates on the slaughter performance of Jinling Flower Chicken

[0101]

[0102] Note: This indicates a significant difference compared to the control group (P<0.05).

[0103] The above embodiments demonstrate that this invention, for the first time, combines known *Lactobacillus casei* R7-6 and *Lactobacillus rhamnosus* R5-8, resulting in a compound microbial agent with significantly better fermentation effects on fiber substrates than a single strain. More importantly, this invention reveals significant differences in the fermentation effects of this compound microbial agent on different fiber-source substrates, making it particularly suitable for the fermentation of *Eriocaulon purpurea* and *Eriocaulon guiminense*. Feeding *Eriocaulon purpurea* or *Eriocaulon guiminense* fermented with this compound microbial agent significantly improves the growth and slaughter performance of broilers, providing an efficient microbial solution to the technical challenge of low utilization of fiber-source feeds and their impact on growth performance in broiler farming, and achieving targeted and efficient utilization of different fiber-source substrates.

[0104] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A compound microbial agent for improving broiler fiber utilization, characterized in that, The compound microbial agent includes Lactobacillus rhamnosus ( Lactobacillus rhamnosus R5-8 strain and Lactobacillus casei ( Lactobacillus casei R7-6 strain, The Lactobacillus rhamnosus ( Lactobacillus rhamnosus The accession number for R5-8 is CCTCC NO:2018436, and the accession date is July 2, 2018; the Lactobacillus casei ( Lactobacillus casei The accession number of R7-6 is CCTCC NO:M2018435, and the accession date is July 2, 2018.

2. The compound microbial agent as described in claim 1, characterized in that, The compound microbial agent is composed of Lactobacillus rhamnosus ( Lactobacillus rhamnosus R5-8 and Lactobacillus casei ( Lactobacillus casei R7-6 was prepared by mixing them at a volume ratio of 1:0.5~2.

3. The compound microbial agent as described in claim 1, characterized in that, The compound microbial agent is composed of Lactobacillus rhamnosus ( Lactobacillus rhamnosus R5-8 and Lactobacillus casei ( Lactobacillus casei R7-6 was prepared by mixing them at a volume ratio of 1:

1.

4. The application of the compound microbial agent as described in claim 1 in the preparation of elephant grass fermented feed.

5. The application as described in claim 4, characterized in that, The raw materials for the fermented elephant grass feed are purple elephant grass and / or Guimin elephant grass.

6. A fermented feed comprising the compound microbial agent according to claim 1, characterized in that, The preparation method of the fermented feed is as follows: crush purple elephant grass and / or Guimin elephant grass, adjust the moisture content to 40-60%, inoculate with Lactobacillus casei strain R7-6 or Lactobacillus rhamnosus strain R5-8 or compound bacterial agent, inoculate into purple elephant grass and / or Guimin elephant grass at an inoculation rate of 100ml / kg, mix evenly, and then seal for fermentation.

7. The application of the fermented feed as described in claim 6 in feeding broiler chickens.

8. The application as described in claim 7, characterized in that, The broiler chickens mentioned are Jinling Flower Chickens.

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