Feed additive, feed containing cinnamyl polyphenol and rosemary essential oil and application thereof

Abstract

The application provides a feed additive containing cinnamomum cassia polyphenol and rosemary essential oil, a feed and application thereof, and belongs to the technical field of beef cattle feed. The feed additive comprises cinnamomum cassia polyphenol and rosemary essential oil, and the weight ratio of the two is preferably 10:1. The additive is added to the basic daily ration of a suckling beef calf, 4 g of cinnamomum cassia polyphenol and 0.4 g of rosemary essential oil are added per kg of feed, which can significantly improve the average daily weight gain and survival rate of the calf, reduce the diarrhea rate and feces score, improve the intestinal mucosal barrier function, improve the body's antioxidant capacity and immune level, and optimize the intestinal flora structure. The synergistic effect of cinnamomum cassia polyphenol and rosemary essential oil is utilized, the problem of high diarrhea rate and poor growth performance of the suckling calf due to the imperfect development of physiological function and immune system is effectively solved, and a green and safe antibiotic replacement scheme is provided for beef cattle breeding.

Description

Technical Field

[0001] This invention belongs to the field of beef cattle feed technology, specifically relating to a composition of cinnamon polyphenols and rosemary essential oil and its application in improving the health and growth performance of lactating beef calves, as well as feed containing the composition. Background Technology

[0002] The health and growth of calves are crucial to the production performance of beef cattle in adulthood and are essential for the sustainable development of the beef cattle industry. Therefore, enhancing calf resistance, reducing morbidity, improving calf growth performance, and minimizing disease incidence are of great significance for improving the economic benefits of beef cattle farming. It is generally believed that during the lactation period after birth, calves are prone to high morbidity rates, especially diarrhea, due to their underdeveloped physiological functions, digestive system, and immune system. This severely impacts calf growth and development and adult growth performance, gradually becoming a bottleneck factor limiting the efficiency of beef cattle farming. For a long time, the extensive use of antibiotics to prevent and treat calf diarrhea during early calf rearing has effectively ensured calf health and enhanced their development, but it has been controversial due to its residual effects. Therefore, with the deepening global ban on antibiotics in feed, finding safe and effective functional green antibiotic alternatives for early calf rearing is an inevitable choice for green and sustainable development.

[0003] During the early rearing period after birth, calves often face invasion by various pathogens due to their low overall immunity, leading to gastrointestinal flora imbalance, inflammatory responses, apoptosis of gastrointestinal epithelial cells, and disruption of tight junctions between mucosal cells. This results in impaired gastrointestinal mucosal barrier function and inhibited growth and development. Furthermore, environmental or nutritional factors can cause oxidative stress in calves, further exacerbating the inflammatory response-immune imbalance and leading to abnormal intestinal barrier function. This results in diarrhea, reduced weight gain, and respiratory diseases, affecting normal growth and development, and in severe cases, causing lifelong developmental delays or even death. Therefore, regulating the balance of calf gastrointestinal flora, reducing inflammation, and improving antioxidant capacity and immune function may be effective methods to improve calf health and growth performance.

[0004] Cinnamon polyphenols (CPS) are a class of bioactive polyphenolic compounds extracted from the dried bark of cinnamon trees. Their main components are flavonoids and their polymers. Studies have shown that CPS not only enhances insulin bioactivity and has hypoglycemic and lipid-lowering effects, but also possesses antioxidant, anti-inflammatory, and macrophage-activating properties, showing potential to regulate macrophage function and potentially influence inflammation reduction and immune function improvement. Current research on CPS focuses primarily on its role in the prevention and treatment of diabetes, periodontitis, and cardiovascular diseases. Rosemary essential oil (REO) is a product collected by distillation of dried rosemary leaves. Its main components are monoterpenes and sesquiterpenes such as 1,8-cineole, α-pinene, camphor, camphene, and borneol. REO has advantages such as small molecular weight, easy penetration, the ability to inhibit tyrosinase activity, and a unique aromatic scent. It also has insecticidal, antibacterial, and antifungal activities and is widely used in cosmetics and food preparation.

[0005] CPS, a key component of cinnamon, is a combination of various types of monomeric polyphenols; rosemary essential oil contains a variety of monoterpenes and sesquiterpenes, characterized by its rich chemical composition and diverse molecular structures. As natural plant extracts, CPS and REO contain various monomeric functional nutrients and may exhibit synergistic and complementary effects, potentially leading to enhanced antioxidant, anti-inflammatory, antibacterial, and immunomodulatory efficacy. However, there are currently no studies or applications of adding CPS to animal feed. REO is mainly used to improve the production performance and quality of livestock products in pigs, dairy cows, and poultry, as well as to regulate methane production in rumen microorganisms of ruminants. Research and applications of combining CPS with REO in regulating the health and growth performance of lactating calves are not yet reported in the literature.

[0006] Newborn calves, during the lactation period from birth to weaning, are highly sensitive to the external environment due to their incomplete physiological and immune development, making them prone to gastrointestinal microbial homeostasis and diarrhea. Calf diarrhea is a common gastrointestinal disease in suckling calves, with a high morbidity, a certain mortality rate, and a serious negative impact on the subsequent growth and development of recovering calves, making it one of the most harmful diseases to the cattle industry. For a long time, the prevention and treatment of calf diarrhea in beef cattle production has relied heavily on antibiotics. However, the overuse of antibiotics has led to drug residues and drug resistance, drawing widespread attention from industry authorities and society. Therefore, finding safe and effective functional green antibiotic alternatives for early calf rearing is an inevitable choice for green and sustainable development in beef cattle production.

[0007] Therefore, developing a green and natural feed additive that can effectively improve the health and growth performance of lactating calves has important practical significance and application value. Summary of the Invention

[0008] This invention aims to address the problem in existing technologies where lactating calves, due to their underdeveloped physiological functions, digestive system, and immune system, suffer from high rates of diarrhea and stunted growth, ultimately affecting the production performance of adult beef cattle. Specifically, this invention provides a feed additive composed of cinnamon polyphenols and rosemary essential oil, and its application. By adding cinnamon polyphenols and rosemary essential oil in a specific ratio to the calf's basal diet, the synergistic effect of the two additives regulates the balance of intestinal flora, enhances intestinal mucosal barrier function, and improves the body's antioxidant capacity and immune function. This significantly reduces the incidence of diarrhea in calves, improves intestinal health, and ultimately effectively enhances the growth performance of lactating calves, providing a safe, green, and residue-free antibiotic alternative solution for the beef cattle industry.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a feed additive comprising cinnamon polyphenols and rosemary essential oil.

[0011] In this invention, cinnamon polyphenols (CPS) are a class of bioactive polyphenolic compounds extracted from the dried bark of cinnamon trees. Their main components are flavonoids and their polymers, with an effective content ≥30%. Cinnamon polyphenols possess antioxidant, anti-inflammatory, and macrophage-activating effects. Rosemary essential oil (REO) is a product collected by distillation of dried rosemary leaves. Its main components are monoterpenes and sesquiterpenes such as 1,8-cineole, α-pinene, camphor, camphene, and borneol, with an effective content ≥99%. Rosemary essential oil is characterized by its small molecular weight, easy penetration, and antibacterial and antifungal activities. This invention is the first to combine cinnamon polyphenols and rosemary essential oil, utilizing their rich chemical composition and diverse molecular structures to achieve a synergistic effect.

[0012] Preferably, the weight ratio of cinnamon polyphenols to rosemary essential oil is (2~8):(0.2~0.8). Within this ratio range, cinnamon polyphenols and rosemary essential oil can fully exert a synergistic effect, effectively improving the growth performance and health of calves.

[0013] More preferably, the weight ratio of cinnamon polyphenols to rosemary essential oil is 10:1. Through extensive experimental screening, this invention has found that when cinnamon polyphenols and rosemary essential oil are combined in a weight ratio of 10:1, their synergistic effect is most significant, exhibiting optimal results in promoting calf weight gain, reducing diarrhea rates, improving intestinal barrier function, enhancing antioxidant capacity, and boosting immunity.

[0014] Secondly, the present invention provides feed containing the aforementioned feed additive.

[0015] Preferably, the feed comprises a basal diet and the feed additives, with 2-8g of cinnamon polyphenols and 0.2-0.8g of rosemary essential oil added per kilogram of feed.

[0016] More preferably, 4g of cinnamon polyphenols and 0.4g of rosemary essential oil are added per kilogram of feed. This invention, through systematic dosage screening experiments (see Examples 1 and 2), demonstrates that when the dosage of cinnamon polyphenols is 4g / kg of feed and the dosage of rosemary essential oil is 400mg / kg of feed, the effect of adding either one is optimal. More importantly, when both are added in combination at this dosage (see Example 3), the effect of increasing daily weight gain and reducing diarrhea rate in calves is significantly better than that of the individual single-agent groups, indicating that cinnamon polyphenols and rosemary essential oil produce an excellent synergistic effect at this ratio.

[0017] In this invention, the basal diet is calf starter feed. Calf starter feed is a well-known feed for the early rearing of calves, and can be conventionally formulated by those skilled in the art according to the nutritional needs of calves. The composition and nutritional levels of the basal diet used in the embodiments of this invention are shown in Table 1.

[0018] Thirdly, the present invention provides the application of cinnamon polyphenols and rosemary essential oil in the preparation of products that improve the health and growth performance of lactating beef calves.

[0019] Preferably, the product is a feed additive or feed.

[0020] In this invention, improving the health and growth performance of lactating beef calves includes one or more of the following aspects: (a) Increase average daily weight gain and final weight of calves; (b) Reduce fecal scores and diarrhea frequency in calves; (c) Reduce serum diamine oxidase (DAO) activity and improve intestinal mucosal barrier function; (d) Increase serum total antioxidant capacity (T-AOC) and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), reduce serum malondialdehyde (MDA) content, and enhance the body's antioxidant capacity; (e) Increase serum immunoglobulin A (IgA) and immunoglobulin G (IgG) levels, regulate inflammatory factor levels, and enhance the body's immune function; (f) Increase the richness and diversity of gut microbiota, optimize gut microbiota structure, reduce the Firmicutes / Bacteroidetes ratio, and increase the relative abundance of beneficial genera (such as Phocaeicola, Faecousia and Faecalibacterium).

[0021] Fourthly, this invention provides the application of cinnamon polyphenols and rosemary essential oil in improving the growth performance of lactating beef calves.

[0022] Fifthly, the present invention provides a method for improving the growth performance of lactating beef calves by adding the feed additive to the calf's basal diet or feeding the calf with the feed additive.

[0023] Preferably, the method includes: adding cinnamon polyphenols and rosemary essential oil to the basal diet of calves, so that each kilogram of basal diet contains 2-8g of cinnamon polyphenols and 0.2-0.8g of rosemary essential oil, mixing evenly, and allowing free access to feed.

[0024] More preferably, 4g of cinnamon polyphenols and 0.4g of rosemary essential oil are added per kilogram of basal diet.

[0025] Preferably, the calf is a lactating beef calf, more preferably a Chinese Simmental beef bull calf. The calf is 7-15 days old, and the experimental period is 40-60 days.

[0026] Preferably, the method further includes the calf nursing from its mother 2 to 4 times a day.

[0027] In this invention, cinnamon polyphenols and rosemary essential oil are mixed with the basal diet and stirred evenly using conventional feed mixing equipment. Both cinnamon polyphenols and rosemary essential oil are natural plant extracts, widely available, easily obtained, and convenient to use, making them suitable for large-scale application in the beef cattle farming industry.

[0028] Compared with the prior art, the series of technical solutions provided by the present invention have the following significant advantages and positive effects:

[0029] First, the feed additive of this invention can significantly improve the growth performance of calves. Experimental results show that adding CPS and REO to the basal diet significantly increased the final weight and average daily weight gain of calves. Specifically, the calves in the CPS+REO combined supplementation group achieved a final weight of 119.66±5.78 kg and an average daily weight gain of 1.26±0.08 kg / d, significantly higher than the control group (final weight 103.98±5.76 kg, daily weight gain 0.95±0.10 kg / d), the CPS-only group (final weight 109.58±6.52 kg, daily weight gain 1.05±0.09 kg / d), and the REO-only group (final weight 113.26±5.86 kg, daily weight gain 1.16±0.07 kg / d) (P<0.05). This indicates that the combined use of CPS and REO has a significant synergistic effect in promoting calf weight gain.

[0030] Secondly, the feed additive of this invention can significantly reduce the diarrhea rate and fecal score in calves. The fecal score of calves in the CPS+REO combined supplementation group decreased to 1.59±0.09, and the diarrhea rate decreased to 5.75%, both significantly lower than the control group (fecal score 2.04±0.10, diarrhea rate 13.00%), the CPS-only group (fecal score 1.81±0.11, diarrhea rate 8.75%), and the REO-only group (fecal score 2.01±0.17, diarrhea rate 12.00%) (P<0.05). This indicates that the combined use of CPS and REO can effectively improve the intestinal health of calves and significantly reduce the risk of diarrhea.

[0031] Furthermore, the feed additive of this invention can improve the intestinal mucosal barrier function of calves. Compared with the control group and the REO group, the serum diamine oxidase (DAO) activity of calves in the CPS+REO combined addition group was significantly reduced (P<0.05), indicating that the intestinal mucosal barrier function was effectively improved.

[0032] Furthermore, the feed additive of this invention can enhance the antioxidant capacity of calves: compared with the control group, CPS group, and REO group, the total antioxidant capacity (T-AOC) and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in the serum of calves in the CPS+REO combined supplementation group were significantly increased (P<0.05); at the same time, compared with the control group and CPS group, the serum malondialdehyde (MDA) content was significantly reduced (P<0.05). This indicates that the combined use of CPS and REO can significantly enhance the antioxidant capacity of calves and effectively alleviate oxidative stress.

[0033] Furthermore, the feed additive of this invention can enhance the immune function of calves. Compared with the control group, CPS group, and REO group, the serum immunoglobulin A (IgA) and immunoglobulin G (IgG) levels in calves in the CPS+REO combined supplementation group were significantly increased (P<0.05); compared with the control group and REO group, the serum interleukin-4 (IL-4) level was significantly increased (P<0.05), and the tumor necrosis factor-α (TNF-α) level was significantly decreased (P<0.05). This indicates that the combined use of CPS and REO can effectively enhance the humoral immune function of calves and inhibit the inflammatory response.

[0034] Furthermore, the feed additive of this invention can optimize the gut microbiota structure of calves: at the phylum level, the relative abundance of Firmicutes in the CPS+REO combined supplementation group decreased, while the relative abundance of Bacteroides increased, and the Firmicutes / Bacteroides ratio decreased, which is beneficial for maintaining calf gut health. At the genus level, the relative abundance of Phocaeicola, Faecousia, and Faecalibacterium was significantly increased in the CPS+REO combined supplementation group (P<0.05), while the relative abundance of Cryptobacteroides was significantly decreased (P<0.05). In addition, the Chao1 index and Shannon index of the gut microbiota in the CPS+REO combined supplementation group were significantly higher than those in the control group and the REO group (P<0.05), indicating that the richness and diversity of gut microbiota were effectively improved.

[0035] In addition, cinnamon polyphenols and rosemary essential oil are both natural plant extracts, which are natural, green and safe, without drug residues or drug resistance issues, and can be promoted and applied in production as important components of calf starter feed. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments (corresponding to the experimental data in the appendix to the specification). It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0037] Materials used in the examples

[0038] The cinnamon polyphenols and rosemary essential oil used in the experiment were purchased from Shaanxi Haoyang Biotechnology Co., Ltd. The main components of cinnamon polyphenols are polyphenols and flavonoids, with an effective content ≥30%; the main components of rosemary essential oil are 1,8-cineole, α-pinene, camphor, and camphene, with an effective content ≥99%.

[0039] The experimental animals were Chinese Simmental beef calves (from a medium-sized cattle farm in Tongliao City, Inner Mongolia Autonomous Region).

[0040] The basal diet for calves is starter feed, and its composition and nutritional levels are shown in Table 1.

[0041] Table 1. Composition and nutrient levels of the basal diet for experimental calves (dry matter basis) %

[0042]

[0043] Each kilogram of premix contains: Vitamin A 1,300,000 IU, Vitamin E 5,000 mg, Vitamin D3 300,000 IU, Copper 1,250 mg, Iron 8,000 mg, Zinc 8,000 mg, Manganese 3,000 mg, Selenium 30 mg, Iodine 100 mg, and Cobalt 30 mg.

[0044] Example 1

[0045] Thirty-two healthy Simmental beef bull calves of similar age (10±2.45 days) and weight (52.09±4.37 kg) were randomly divided into four groups of eight calves each. The four groups were: control group, CPS1 group, CPS2 group, and CPS3 group. The control group calves were fed a basal diet, while the CPS1 group was fed a basal diet containing 2g CPS per kilogram, the CPS2 group was fed a basal diet containing 4g CPS per kilogram, and the CPS3 group was fed a basal diet containing 8g CPS per kilogram. The preliminary trial period was 7 days, and the formal trial period was 50 days. The basal diet for the experimental calves was starter feed, and CPS was mixed with the basal diet and allowed free access. The calves were also nursed by their mothers three times a day (7:00, 11:00, and 17:00) until the end of the trial. The composition and nutrient levels of the basal diet are shown in Table 1. During the experiment, the enclosures were regularly disinfected and cleaned, and the animals were provided with free drinking water. The enclosures were kept clean, dry, well-ventilated, and at a suitable temperature.

[0046] On the mornings of days 1 and 50 of the formal trial for each treatment calf, calves were weighed on an empty stomach, and the average daily gain (ADG) was calculated. Average daily gain (ADG) = (final weight - initial weight) / number of trial days. Additionally, the fecal condition of each group of calves was observed and scored daily during the trial. Normal morphology and firm appearance: 1 point; formed morphology and soft appearance: 2 points; unformed morphology and watery appearance: 3 points; unformed morphology, watery appearance with mucus and a small amount of blood: 4 points; unformed morphology, watery appearance with mucus and a large amount of blood: 5 points. A calf with a fecal score ≥3 was considered to have diarrhea. The diarrhea frequency was calculated based on the recorded number of calves with diarrhea and the duration of diarrhea. Diarrhea frequency = (number of calves with diarrhea * number of days of diarrhea in calves) / (number of experimental calves * number of experimental days) × 100%, and the results are shown in Tables 2 and 3.

[0047] Table 2 Effects of CPS supplementation on body weight of beef calves

[0048]

[0049] Table 3. Effects of dietary CPS supplementation on fecal score and diarrhea rate in beef calves

[0050]

[0051] Note: Different lowercase letters in the superscript of data in the same row indicate significant differences (P<0.05), while the same letter indicates no significant differences (P>0.05). The same applies below.

[0052] The results showed that dietary supplementation with cinnamylphenol in beef calves tended to increase final weight and daily weight gain compared to the control group, with CPS-2 showing the best effect and significantly increasing daily weight gain, although the differences between groups were not significant (P>0.05). Furthermore, dietary supplementation with cinnamylphenol in beef calves tended to decrease fecal scores and diarrhea rates compared to the control group, with CPS-2 showing the best effect and significantly reducing fecal scores and diarrhea rates (P<0.05).

[0053] Example 2

[0054] Twenty-eight healthy Simmental beef bull calves of similar age (11±2.65 d) and weight (51.83±4.94 kg) were randomly divided into four groups of seven calves each. The four groups were: control group, REO 1 group, REO 2 group, and REO 3 group. The control group calves were fed a basal diet; REO 1 group was fed a basal diet containing 200 mg REO per kg; REO 2 group was fed a basal diet containing 400 mg REO per kg; and REO 3 group was fed a basal diet containing 800 mg REO per kg. The preliminary trial period was 7 days, and the formal trial period was 50 days. The basal diet for the experimental calves was starter feed, with REO mixed with the basal diet and allowed free access. The calves were also nursed by their mothers three times a day (7:00, 11:00, and 17:00) until the end of the trial. The composition and nutrient levels of the basal diet are shown in Table 1. During the experiment, the enclosures were regularly disinfected and cleaned, and the animals were provided with free drinking water. The enclosures were kept clean, dry, well-ventilated, and at a suitable temperature.

[0055] On the mornings of days 1 and 50 of the formal trial for each treatment calf, the calves were measured on an empty stomach, and the average daily gain (ADG) was calculated. Average daily gain (ADG) = (final weight - initial weight) / number of trial days. Additionally, the fecal condition of each group of calves was observed and scored daily during the trial. The number of calves with diarrhea and the duration of diarrhea were recorded, and the diarrhea frequency was calculated. The fecal scoring criteria and diarrhea frequency calculation method were the same as in Example 1. The results are shown in Tables 4 and 5.

[0056] Table 4 Effects of REO supplementation on body weight of calves

[0057]

[0058] Table 5. Effects of REO supplementation in diet on fecal score and diarrhea rate in beef calves

[0059]

[0060] The results showed that supplementing the diets of beef calves with REO tended to increase their final weight and daily weight gain compared to the control group, with REO2 showing the best effect and significantly increasing daily weight gain, but the differences among the REO groups were not significant (P>0.05). In addition, supplementing the diets of beef calves with REO2 tended to decrease their fecal scores and diarrhea rate compared to the control group, but the differences among the groups were not significant (P>0.05).

[0061] Example 3

[0062] Thirty-two healthy Simmental beef calves of similar age (10±2.71 days) and weight (50.89±3.26 kg) were randomly divided into four groups of eight calves each. The four groups were: a control group, a CPS group, a REO group, and a CPS+REO group. The control group was fed a basal diet; the CPS group was fed a basal diet containing 4g CPS per kg; the REO group was fed a basal diet containing 400mg REO per kg; and the CPS+REO group was fed a basal diet containing both 4g CPS and 400mg REO per kg. The preliminary trial period was 7 days, and the formal trial period was 50 days. The basal diet for the experimental calves was a starter feed. CPS and REO were mixed with the basal diet and allowed free access to feed. The calves were also nursed by their mothers three times a day (7:00, 11:00, and 17:00) until the end of the trial. The composition and nutrient levels of the basal diet are shown in Table 1. During the experiment, the enclosures were regularly disinfected and cleaned, and the animals were provided with free drinking water. The enclosures were kept clean, dry, well-ventilated, and at a suitable temperature.

[0063] On the mornings of days 1 and 50 of the formal trial for each treatment calf, the calf's weight was measured on an empty stomach, and the average daily gain (ADG) was calculated. Average daily gain (ADG) = (final weight - initial weight) / number of trial days. Calf survival rate was recorded on day 90 of the formal trial. Results are shown in Table 6.

[0064] In addition, the fecal condition of calves in each group was observed and scored daily during the experiment. The number of calves with diarrhea and the duration of diarrhea were recorded, and the frequency of diarrhea was calculated. The fecal scoring criteria and the method for calculating the frequency of diarrhea were the same as in Example 1. The results are shown in Table 7.

[0065] Table 6. Effects of dietary supplementation with CPS and REO on body weight and survival rate of calves.

[0066]

[0067] Table 7 Effects of dietary supplementation with CPS and REO on fecal score and diarrhea rate in beef calves

[0068]

[0069] The results showed that the diets supplemented with CPS+REO resulted in significantly higher ending weight and daily weight gain for beef calves compared to the control, CPS, and REO groups (P<0.05), but there was no significant difference in calf survival rate among the groups (P>0.05). Furthermore, the diets supplemented with CPS+REO resulted in significantly lower fecal scores and diarrhea rates for beef calves compared to the control, CPS, and REO groups (P<0.05).

[0070] On the last day of the experiment, 10 mL of blood was collected from the jugular vein of each group of calves in the morning while they were fasting. The blood was allowed to stand at room temperature for 30 min, then centrifuged at 3500 r / min for 15 min. The serum was collected in dried EP tubes and stored at -80℃ for the determination of serum biochemistry, intestinal barrier permeability, antioxidant, and immune indicators. An automated biochemical analyzer was used to detect serum biochemical indicators. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum intestinal barrier permeability, immune levels, and antioxidant levels. The experimental procedures were performed according to the kit instructions. The results are shown in Tables 8, 9, 10, and 11.

[0071] As shown in Table 8, compared with the control and REO groups, the CPS2 group of beef calves supplemented with CPS+REO showed significantly reduced serum DAO activity (P<0.05).

[0072] Table 8 Effects of CPS and REO on serum DAO levels in beef calves

[0073]

[0074] As shown in Table 9, compared with the control, CPS and REO groups, the addition of CPS+REO to the diet of beef calves significantly reduced serum BUN and ALT levels (P<0.05), and significantly reduced serum AST levels compared with the control and REO groups (P<0.05). However, there were no significant differences in serum total protein, glucose and triglyceride levels among the groups (P>0.05).

[0075] Table 9 Effects of CPS and REO on serum biochemical parameters in beef calves

[0076]

[0077] As shown in Table 10, compared with the control, CPS and REO groups, the addition of CPS+REO to the diet of beef calves significantly increased serum T-AOC and the activities of SOD, GSH-Px and CAT (P<0.05), while the serum MDA content was significantly reduced compared with the control and CPS groups (P<0.05).

[0078] Table 10 Effects of CPS and REO on serum antioxidant levels in calves

[0079]

[0080] As shown in Table 11, compared with the control, CPS, and REO groups, dietary supplementation with CPS+REO significantly increased serum IgA and IgG levels in beef calves (P<0.05), while serum IL-4 was significantly increased compared with the control and REO groups (P<0.05). Furthermore, dietary supplementation with CPS+REO significantly decreased serum TNF-α levels compared with the control and REO groups (P<0.05).

[0081] Table 11 Effects of CPS and REO on serum immune markers in beef calves

[0082]

[0083] On the last day of the experiment, fecal samples were collected from the deep rectum of calves, rapidly frozen in liquid nitrogen, and stored at -80 °C for later analysis. Libraries were constructed using the TruSeq Nano DNA LT Library Prep Kit (Illumin, USA), and the V3-V4 regions of 16S rDNA were amplified using specific primers 338F (5'-barcode+ACTCCTACGGGAGGCAGCA-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3'). Library construction and sequencing analysis were performed by Shanghai Paisenuo Biotechnology Co., Ltd., and the relative abundance of gut microbiota at the phylum and genus levels was analyzed. The results are shown in Tables 12 and 13.

[0084] Table 12 Effects of CPS and REO on the α-diversity of gut microbiota in beef calves

[0085]

[0086] As shown in Table 12, the Chao and Shannon indices of calves in the CPS+REO group were significantly higher than those in the control and REO groups (P<0.05), and showed an increasing trend relative to the CPS group, while the Simpson index showed no significant difference (P>0.05). The coverage indices of all groups were above 0.98, indicating that they sufficiently reflected the gut microbiota of calves. Alpha diversity is an important indicator for measuring the richness and diversity of gut microbiota. The Chao1 and Shannon indices represent alpha diversity, with the Chao1 index reflecting the richness of sample species and the Shannon index reflecting the diversity of sample species. The results indicate that adding 4g of CPS + 400mg of REO per kilogram of diet can effectively improve the richness and diversity of gut microbiota in lactating calves.

[0087]

[0088] Table 13 Effects of CPS and REO on the major gut microbiota structure of beef calves

[0089] As shown in Table 13, at the phylum level, the dominant gut microbiota in each group of calves mainly consisted of Firmicutes, Bacteroides, Actinobacteriota, and Proteobacteria. Compared with the control, the relative abundance of Bacteroides and Proteobacteria was significantly increased in the CPS+REO group (P<0.05), while the relative abundance of Actinobacteriota was significantly decreased. Studies have clearly established that the Firmicutes / Bacteroides ratio is an important indicator of intestinal health in animals. An increase in this ratio will lead to an imbalance in gut microbiota homeostasis, triggering intestinal mucosal barrier dysfunction or inflammation. Importantly, compared with the control, CPS group and REO group, the CPS+REO group showed a decreasing trend in Firmicutes and an increasing trend in Bacteroidetes, which in turn reduced the Firmicutes / Bacteroidetes ratio, which is beneficial for maintaining the intestinal health of calves.

[0090] Furthermore, at the genus level, compared with the control and CPS, the relative abundance of the genera *Phocaeicola*, *Faecousia*, and *Faecalibacterium* was significantly increased in the CPS+REO group (P<0.05), while the abundance of the genus *Cryptobacteroides* was significantly decreased (P<0.05). These results indicate that supplementing the diet with 4g CPS + 400mg REO per kilogram of feed can improve the gut microbiota structure at both the phylum and genus levels in lactating calves, reduce diarrhea rates, and promote calf health.

[0091] The cinnamon polyphenol and rosemary essential oil feed additives provided by this invention are made from natural, green, and safe raw materials. The preparation method is simple and easy for industrial production. This invention can be widely applied to the early rearing of suckling calves in the beef cattle industry, effectively improving the health and growth performance of calves, reducing the incidence of diarrhea and mortality, and reducing the use of antibiotics. It has good economic and social benefits and is suitable for large-scale promotion and application in the beef cattle industry.

Claims

1. A feed additive, characterized in that, It includes cinnamon polyphenols and rosemary essential oil.

2. The feed additive according to claim 1, characterized in that, The weight ratio of cinnamon polyphenols to rosemary essential oil is (2~8):(0.2~0.8).

3. The feed additive according to claim 2, characterized in that, The weight ratio of cinnamon polyphenols to rosemary essential oil is 10:

1.

4. A feed containing any one of the feed additives described in claims 1-3.

5. The feed according to claim 4, characterized in that, The diet includes a basal diet and the feed additives, wherein each kilogram of feed contains 2-8g of cinnamon polyphenols and 0.2-0.8g of rosemary essential oil.

6. The feed according to claim 5, characterized in that, Each kilogram of feed contains 4g of cinnamon polyphenols and 0.4g of rosemary essential oil.

7. Application of cinnamon polyphenols and rosemary essential oil in the preparation of products that improve the health and growth performance of lactating beef calves.

8. The product according to claim 7, characterized in that, The product is a feed additive or feed.

9. Application of cinnamon polyphenols and rosemary essential oil in improving the growth performance of lactating beef calves.

10. A method for improving the growth performance of lactating beef calves, characterized in that, The feed additives according to any one of claims 1 to 3 are added to the basal diet of calves, or the calves are fed with the feed according to any one of claims 4 to 6.

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