Feed composition and application thereof in increasing content of vitamin A in raw milk

Abstract

The invention relates to the technical field of feeds, in particular to a feed composition and application thereof in increasing the content of vitamin A in raw milk. After dairy cows are fed with the feed composition, the content of vitamin A in raw milk can be remarkably increased, meanwhile, the flavor and taste of the milk prepared from the raw milk are improved, the stability of the vitamin A in the storage process of the milk is guaranteed, an effective method is provided for preparing the milk with the high vitamin A content, and the feed composition is worthy of popularization and application. The method is of great significance in improving the nutritional value of milk.

Description

Technical Field

[0001] This invention relates to the field of feed technology, and in particular to a feed composition and its application in increasing the vitamin A content in raw milk. Background Technology

[0002] Vitamin A is a class of compounds with retinol activity. It constitutes a component of the photosensitive substances in visual cells and is an important nutrient for maintaining night vision. In addition, vitamin A acts as a coenzyme to regulate glycoprotein synthesis, which is crucial for maintaining the morphology and function of epithelial cells. Through binding to specific retinoic acid receptors in the cell nucleus, vitamin A also plays a role in maintaining and regulating immunity. Furthermore, vitamin A participates in gene regulation by binding to retinoic acid receptors, playing an important physiological role in cell differentiation, cartilage formation, and reproductive function.

[0003] Milk is a food rich in nutrients with a suitable composition ratio, easily digestible, and of extremely high nutritional value. It provides humans with high-quality protein, calcium, vitamin B2, and other nutrients, and the lactose in it can promote the absorption of minerals such as calcium, iron, and zinc. The vitamin A content in milk is typically 40 μg RE / 100g, and some loss occurs during processing and storage. Vitamin A in milk decomposes under light conditions, and the resulting oxidized odor gradually increases over the shelf life. Therefore, increasing the vitamin A content and stability in raw milk is of great significance for improving the nutritional value of milk. Previous studies have attempted to increase the vitamin A content in raw milk by adding vitamin A to dairy cow diets, but the increase remains relatively limited. Summary of the Invention

[0004] This invention provides a feed composition and its application in increasing the vitamin A content in raw milk.

[0005] This invention aims to develop a feed composition for dairy cows to increase the vitamin A content in raw milk. During the research and development process, this invention discovered that the simultaneous addition of alfalfa, whole-plant corn, and red clover to roughage can have a synergistic effect, significantly increasing the vitamin A content in the milk produced by dairy cows, while also improving the stability of vitamin A in the milk and the flavor and taste of the milk.

[0006] Specifically, the present invention provides the following technical solutions.

[0007] The present invention provides a feed composition comprising feed additives, concentrates and roughage; wherein the roughage comprises alfalfa, whole-plant forage corn and red clover.

[0008] Preferably, the mass ratio of alfalfa, whole-plant corn, and red clover in the roughage is (35-45):(30-40):(12-18). Controlling the ratio of alfalfa, whole-plant corn, and red clover within the above range is beneficial for the three to exert a synergistic effect, thereby more effectively improving the vitamin A content in the milk produced by dairy cows and its stability during milk storage.

[0009] In this invention, alfalfa, whole-plant forage corn, and red clover are all fresh forage. This invention has found that, compared to using dried forage or silage, using freshly harvested forage is more beneficial in increasing the vitamin A content in raw milk and its stability during milk storage.

[0010] Preferably, alfalfa is harvested during the initial flowering stage, from the first flower to about 1 / 10 of the plant's flowers; whole-plant forage corn is harvested during the milk line stage (1 / 2 to 3 / 4 of the plant's length); and red clover is harvested from the initial flowering stage to full bloom. This invention has found that harvesting alfalfa, whole-plant forage corn, and red clover at the aforementioned times allows for better synergistic effects, which is more conducive to increasing the vitamin A content in raw milk and its stability during milk storage.

[0011] Preferably, the roughage also includes alfalfa meal.

[0012] Preferably, the roughage comprises the following components in parts by weight: 35-45 parts alfalfa, 30-40 parts whole-plant feed corn, 12-18 parts red clover, and 7-13 parts alfalfa meal.

[0013] In the feed composition described above, the concentrate includes corn gluten meal at a mass ratio of 20% to 24%. This invention has found that adding corn gluten meal to the concentrate helps to increase the vitamin A content in raw milk and its stability in processed milk.

[0014] Preferably, the concentrate comprises the following components in parts by weight: 6-16 parts corn, 20-24 parts corn gluten meal, 16-24 parts rice bran, 25-35 parts wheat bran, 8-12 parts fat powder, 0.5-1.5 parts sodium bicarbonate, 1-3 parts salt, and 3-5 parts premix.

[0015] The premix in the above-mentioned concentrate is a mixture of vitamins and minerals.

[0016] Preferably, the premix comprises vitamin D, MgSO4, FeSO4, CuSO4, MnSO4, KI and CoCl2.

[0017] Preferably, each kg of premix comprises: vitamin D 13000-17000 IU, MgSO4 100-140g, FeSO4 2-3g, CuSO4 8-9g, MnSO4 9.5-10.5g, KI 0.05-0.2g, and CoCl2 0.15-0.25g.

[0018] In the above premix, the functions of MgSO4, FeSO4, CuSO4, MnSO4, KI, and CoCl2 are all to provide the corresponding inorganic salt ions. Therefore, those skilled in the art will understand that the above inorganic salts can be replaced with other types of inorganic salts corresponding to the inorganic salt ions. For example, MgSO4 can be replaced with MgCl2, CuSO4 can be replaced with CuCl2, etc. When replacing with other inorganic salts, their dosage can be calculated according to the content of the corresponding salt ions of the above inorganic salts. These replacements are equivalent replacements of the present invention.

[0019] In the feed composition described above, the feed additives include β-carotene, vitamin A or its derivatives, vitamin E or its derivatives, yeast selenium, and emulsifiers.

[0020] Among the above feed additives, β-carotene, as a precursor of vitamin A, can be converted into vitamin A in the body. The combination of β-carotene and vitamin A increases the conversion substrate of vitamin A in dairy cows. At the same time, the addition of vitamin E or its derivatives and yeast selenium reduces the oxidative loss of vitamin A in the body. Combined with the addition of emulsifiers, the release and absorption efficiency of β-carotene, vitamin A and vitamin E in the intestine is improved. Preferably, the feed additive further includes maltodextrin. Maltodextrin, as a carrier of the additive, helps to ensure that other components of the feed additive are evenly dispersed in the feed.

[0021] Preferably, the feed additive comprises the following components in parts by weight: 45-75 parts β-carotene, 25-55 parts vitamin A or its derivatives, 120-200 parts vitamin E or its derivatives, 360-640 parts yeast selenium, 130-300 parts maltodextrin, and 10-40 parts emulsifier.

[0022] The above-mentioned vitamin A derivatives can be vitamin A esters, such as vitamin A acetate; vitamin E derivatives can be vitamin E esters, such as α-tocopherol acetate.

[0023] The emulsifier is preferably selected from at least one of sorbitan fatty acid esters, bile salts, and lecithin.

[0024] Preferably, the feed additive is a coated granule. Coating the feed additive (rumen-processing) helps reduce the metabolic loss of fat-soluble nutrients such as vitamin A and β-carotene in the rumen, increases their release rate in the intestine, and thus improves their absorption and utilization rate.

[0025] In some specific embodiments of the present invention, the coating solution used in the coating treatment comprises the following components: 3-5 parts chitosan, 1-2 parts magnesium stearate, 1-2 parts calcium carbonate, 0.3-0.7 parts talc, and 0.3-0.7 parts diethyl phthalate. Preferably, a fluidized bed granulation dryer is used for spray coating.

[0026] In the feed composition described above, the dry matter mass ratio of roughage, concentrate and feed additive is preferably (50~54):(42~48):(2~4).

[0027] The present invention provides a method for preparing the feed composition described above, the method comprising: first mixing concentrate and feed additives to obtain a concentrate mixture, and then mixing roughage with the concentrate mixture.

[0028] The present invention also provides any of the following applications of the feed compositions described above: (1) Application in dairy cow feeding; (2) Application in increasing the vitamin A content in raw milk, improving the taste and flavor of milk and / or improving the stability of vitamin A in milk; (3) Application in the preparation of dairy cow feed.

[0029] In the above application, improving the stability of vitamin A in milk refers to improving the stability of vitamin A in milk during storage.

[0030] In the above applications, increasing the vitamin A content in raw milk, improving the taste and flavor of milk, and / or improving the stability of vitamin A in milk are achieved by feeding dairy cows with the feed composition described above.

[0031] The present invention provides a dairy cow feed, wherein the feed comprises the feed composition described above.

[0032] The beneficial effects of this invention include at least the following: the feed composition provided by this invention can significantly increase the vitamin A content in raw milk (reaching 100 μgRE / 100g or more) after feeding dairy cows; the milk processed from this raw milk has a better flavor and taste, a slightly yellow color, and a distinctive grassy aroma; the vitamin A content in the milk product is significantly increased (reaching 80 μgRE / 100g or more); and the vitamin A in the milk exhibits high stability during processing and storage. The feed composition of this invention provides an effective method for preparing milk with high vitamin A content, which is of great significance for improving the nutritional value of milk and has good application prospects. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] In the following examples, the alfalfa was harvested from the first flower to the initial flowering stage (1 / 10 of the plant is in bloom), the whole-plant forage corn was harvested from the milk line stage (1 / 2 to 3 / 4 of the plant is in bloom), and the red clover was harvested from the initial flowering stage to the peak flowering stage.

[0035] Example 1

[0036] This embodiment provides a feed composition comprising roughage, concentrate, and feed additives, wherein the dry matter mass ratio of roughage, concentrate, and feed additives is 52:45:3; wherein the composition of the roughage is as follows (mass percentage): 40% alfalfa, 35% whole-plant feed corn, 15% red clover, and 10% alfalfa meal.

[0037] The composition of the concentrate is as follows (by weight percentage): corn 11%, corn gluten meal 22%, rice bran 20%, wheat bran 30%, fat powder 10%, sodium bicarbonate 1%, salt 2%, and premix 4%. The premix contains the following components: vitamin D 15000 IU / kg, MgSO4 120g / kg, FeSO4 2.4g / kg, CuSO4 8.4g / kg, MnSO4 9.9g / kg, KI 0.1g / kg, and CoCl2 0.2g / kg.

[0038] The feed additive comprises β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester in a mass ratio of 60:40:160:500:220:20. Its preparation method is as follows: β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester are mixed and coated with a 60-fold dilution of coating solution. The coating solution formula is: chitosan 4%, magnesium stearate 1.5%, calcium carbonate 1.5%, talc 0.5%, and diethyl phthalate 0.5%. Spray coating is performed using a fluidized bed granulation dryer. The process parameters are: air source pressure 0.5 MPa, airtight pressure 0.3 MPa, atomization pressure 0.4 MPa, peristaltic pump 5-6 r / min, inlet air temperature 40℃, outlet air temperature 20℃, and damper 75%-95%.

[0039] The preparation method of the feed composition is as follows: feed additives and concentrates are fully mixed in a mixer to form a concentrate mixture; the concentrate mixture is fully mixed with roughage to form a complete diet.

[0040] Example 2

[0041] This embodiment provides a feed composition comprising feed additives, concentrates, and roughage, wherein the dry matter mass ratio of the feed additives, concentrates, and roughage is 4:42:54; wherein the roughage composition is as follows (mass percentage): alfalfa 35%, whole-plant feed corn 40%, red clover 12%, and alfalfa meal 13%.

[0042] The composition of the concentrate is as follows (by weight percentage): corn 6%, corn gluten meal 24%, rice bran 16%, wheat bran 35%, fat meal 10.5%, sodium bicarbonate 0.5%, salt 3%, and premix 5%. The premix contains the following components: vitamin D 13000 IU / kg, MgSO4 140 g / kg, FeSO4 2 g / kg, CuSO4 9 g / kg, MnSO4 9.5 g / kg, KI 0.2 g / kg, and CoCl2 0.15 g / kg.

[0043] The feed additive comprises β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester in a mass ratio of 45:55:120:640:130:10. Its preparation method is as follows: β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester are mixed and coated with an 80-fold dilution of coating solution. The coating solution formula is: chitosan 4%, magnesium stearate 1.5%, calcium carbonate 1.5%, talc 0.5%, and diethyl phthalate 0.5%. Spray coating is performed using a fluidized bed granulation dryer. The process parameters are: air source pressure 0.5 MPa, airtight pressure 0.3 MPa, atomization pressure 0.4 MPa, peristaltic pump 5-6 r / min, inlet air temperature 40℃, outlet air temperature 20℃, and damper 75%-95%.

[0044] The preparation method of the feed composition is as follows: feed additives and concentrates are fully mixed in a mixer to form a concentrate mixture; the concentrate mixture is fully mixed with roughage to form a complete diet.

[0045] Example 3

[0046] This embodiment provides a feed composition comprising feed additives, concentrates and roughage, wherein the dry matter mass ratio of the feed additives, concentrates and roughage is 2:48:50; wherein the roughage composition is as follows (mass percentage): alfalfa 45%, whole-plant feed corn 30%, red clover 18%, alfalfa meal 7%.

[0047] The composition of the concentrate is as follows (by weight percentage): corn 16%, corn gluten meal 20%, rice bran 24%, wheat bran 25%, fat meal 9.5%, sodium bicarbonate 1.5%, salt 1%, and premix 3%. The premix contains the following components: vitamin D 15000 IU / kg, MgSO4 120 g / kg, FeSO4 2.4 g / kg, CuSO4 8.4 g / kg, MnSO4 9.9 g / kg, KI 0.1 g / kg, and CoCl2 0.2 g / kg.

[0048] The feed additive comprises β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester in a mass ratio of 75:25:200:360:300:40. Its preparation method is as follows: β-carotene, vitamin A acetate, α-tocopherol acetate, yeast selenium, maltodextrin, and sorbitan fatty acid ester are mixed and coated with a 40-fold dilution of coating solution. The coating solution formula is: chitosan 4%, magnesium stearate 1.5%, calcium carbonate 1.5%, talc 0.5%, and diethyl phthalate 0.5%. Spray coating is performed using a fluidized bed granulation dryer. The process parameters are: air source pressure 0.5 MPa, airtight pressure 0.3 MPa, atomization pressure 0.4 MPa, peristaltic pump 5-6 r / min, inlet air temperature 40℃, outlet air temperature 20℃, and damper 75%-95%.

[0049] The preparation method of the feed composition is as follows: feed additives and concentrates are fully mixed in a mixer to form a concentrate mixture; the concentrate mixture is fully mixed with roughage to form a complete diet.

[0050] Comparative Example 1

[0051] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that red clover is removed from the roughage and the proportion of alfalfa meal is adjusted to 25%.

[0052] Comparative Example 2

[0053] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that: whole-plant feed corn is removed from the roughage, the proportion of red clover is adjusted to 35%, and the proportion of alfalfa meal is adjusted to 25%.

[0054] Comparative Example 3

[0055] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that: alfalfa is removed from the roughage, the proportion of whole-plant feed corn is adjusted to 50%, the proportion of red clover is adjusted to 25%, and the proportion of alfalfa meal is adjusted to 25%.

[0056] Comparative Example 4

[0057] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that the red clover in the roughage is replaced with sheep grass.

[0058] Comparative Example 5

[0059] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that the whole-plant feed corn in the roughage is replaced with corn silage.

[0060] Comparative Example 6

[0061] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that alfalfa grass in the roughage is replaced with alfalfa hay.

[0062] Comparative Example 7

[0063] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that the corn gluten meal in the concentrate is removed, and the other components are adjusted as follows (mass percentage): corn 33%, rice bran 20%, wheat bran 30%, fat meal 10%, sodium bicarbonate 1%, salt 2%, and premix 4%.

[0064] Comparative Example 8

[0065] This comparative example provides a feed composition that differs from the feed composition of Example 1 only in that the corn gluten meal in the concentrate is replaced with soybean meal.

[0066] Experimental Example 1

[0067] The rumen degradation rate and intestinal fluid release rate of vitamin A contained in the feed compositions of each embodiment and comparative example were analyzed. The specific methods and results are described below.

[0068] Accurately weigh 4g of the diet (i.e., the feed composition of the examples and comparative examples) and place it into a 5cm×8cm nylon bag. Tie the nylon bag with nylon thread and then tie it to a hemp rope. Fix one end of the hemp rope to the rumen fistula of the cow with the fistula, and insert the other end with the nylon bag into the bottom of the cow's rumen to seal the rumen fistula. After 24 hours of digestion, remove the nylon bag. Rinse one portion simply with distilled water and set aside for the next digestion step; wash the other portion and dry it at 60℃ for 48 hours until constant weight, and collect the residue in the nylon bag.

[0069] After rumen fluid digestion, the nylon bag was placed in a 0.1 mol / L hydrochloric acid-protease (pH=2) solution and incubated at 39℃ for 1 h. Then, the nylon bag was simply rinsed and placed in a 0.5 mol / L KH₂PO₄-trypsin (pH=7.75) solution and incubated at 39℃ for another 24 h. After incubation, the nylon bag was washed and dried to constant weight. The bag was then loosened, and the digested residue was collected. The vitamin A content in the rumen and intestinal fluid digested residue was determined according to GB / T 17817-2010, "Determination of Vitamin A in Feed - High Performance Liquid Chromatography". The degradation rate of vitamin A in the rumen and the release rate in the intestinal fluid were calculated. The results are shown in Table 1.

[0070] The formula for calculating the rumen degradation rate is as follows: ; The formula for calculating the intestinal fluid release rate is: ×100%.

[0071] Table 1. Rumen degradation rate and intestinal fluid release rate of vitamin A in feed

[0072] Experimental Example 2

[0073] The feed compositions of each embodiment and comparative example were used as diets to feed dairy cows to detect the effects of different feed compositions on the vitamin A content in raw milk and on the flavor, taste and stability of processed milk.

[0074] Twenty adult Holstein dairy cows weighing 530-570 kg, with a lactation period of 200-240 days and a milk yield of 20-25 kg / day or more were selected and fed for 56 days. The herd was adjusted according to the cows' health status. The cows were fed and milked three times a day, and milk samples were collected weekly using the milking machine's diverter. Milk samples collected in the morning, noon, and evening were mixed in a 4:3:3 ratio and sent for testing for eight consecutive weeks. The vitamin A content in the raw milk samples was determined according to GB 5009.82 National Food Safety Standard - Determination of Vitamins A, D, and E in Food.

[0075] When the cows are nearing the end of their feeding period, raw milk is collected using a milking machine. Within 30 minutes of milking, the milk temperature is rapidly cooled to 2-3°C, with 800 kg of raw milk collected within one day. The collected raw milk is transported to the dairy processing plant by milk truck within 4 hours, with the temperature of the milk truck tanks not exceeding 7°C during storage and transportation. Raw milk is accepted only after its testing indicators meet the GB 19301 Raw Milk standard. The received raw milk is filtered through a filter of at least 80 mesh and stored in storage tanks equipped with agitators. After purification, the milk is heated to 68°C for degassing, followed by homogenization. The total homogenization pressure is set at 20 MPa, with a secondary homogenization pressure of 4 MPa. Ultra-high temperature (UHT) sterilization is performed using a tubular heating system. The milk is first slowly heated to 100°C and maintained for 100 seconds; then slowly heated to 135°C and maintained for 4 seconds; finally, the milk is cooled to room temperature within 50 seconds and then bottled.

[0076] After the product was stored at room temperature (20℃) for two weeks after production, a sensory evaluation was conducted. Fifteen professionally trained R&D personnel were invited to taste and score the product, using descriptive terms such as surface whiteness, milk flavor, sweetness, steamed flavor, grassy flavor, and creaminess. The sensory flavor intensity was scored from 0 to 9, with 0 indicating no flavor and 9 indicating a very strong flavor. Subsequently, the product was stored at room temperature for six months, and the vitamin A content was tested according to GB 5009.82 National Food Safety Standard for the Determination of Vitamins A, D, and E in Food.

[0077] Table 2 shows the trend of vitamin A content in raw milk over 8 consecutive weeks after feeding dairy cows with the diets of the various embodiments and comparative examples. Overall, after 4 weeks of dietary adjustment, vitamin A in raw milk reached a relatively stable level. After feeding with the feed compositions of the various embodiments, the vitamin A content in raw milk was significantly higher than that of the comparative examples.

[0078] Table 2. Changes in Vitamin A Content (μgRE / 100g) in Raw Milk

[0079] The sensory evaluation results of the processed milk produced by feeding dairy cows with the feed compositions of each embodiment and comparative example are shown in Table 3. The surface whiteness of the milk is affected by the vitamin A content; the lower the vitamin A content, the higher the surface whiteness of the milk.

[0080] Table 3 Sensory scores of processed milk

[0081] Table 4 shows the changes in vitamin A content in processed milk produced from milk fed with the feed compositions of each embodiment and comparative example during room temperature storage. After 6 months of storage, the vitamin A content in processed milk produced from milk fed with the feed compositions of each embodiment can still be maintained above 80 μgRE / 100g, with a decay rate of 7%-11.4%.

[0082] Table 4. Changes in Vitamin A Content (μgRE / 100g) in Processed Milk under Room Temperature Storage Conditions

[0083] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A feed composition, characterized in that, The feed composition includes feed additives, concentrates, and roughage; The roughage includes alfalfa, whole-plant forage corn, and red clover.

2. The feed composition according to claim 1, characterized in that, The roughage consists of alfalfa, whole-plant forage corn and red clover in a mass ratio of (35~45):(30~40):(12~18).

3. The feed composition according to claim 1 or 2, characterized in that, Alfalfa, whole-plant forage corn, and red clover are all fresh forage grasses; Preferably, alfalfa is harvested when the plant has opened its first flower to the initial flowering stage (when 1 / 10 of the flowers have bloomed); whole-plant forage corn is harvested when it is 1 / 2 to 3 / 4 of the milk line stage; and red clover is harvested when it is in its initial flowering stage to its peak flowering stage.

4. The feed composition according to any one of claims 1 to 3, characterized in that, The roughage comprises the following components in parts by weight: 35-45 parts alfalfa, 30-40 parts whole-plant feed corn, 12-18 parts red clover, and 7-13 parts alfalfa meal.

5. The feed composition according to any one of claims 1 to 4, characterized in that, The concentrate includes corn gluten meal at a mass ratio of 20% to 24%; Preferably, the concentrate comprises the following components in parts by weight: 6-16 parts corn, 20-24 parts corn gluten meal, 16-24 parts rice bran, 25-35 parts wheat bran, 8-12 parts fat powder, 0.5-1.5 parts sodium bicarbonate, 1-3 parts salt, and 3-5 parts premix.

6. The feed composition according to claim 5, characterized in that, The premix includes vitamin D, MgSO4, FeSO4, CuSO4, MnSO4, KI and CoCl2; Preferably, each kg of premix contains 13,000-17,000 IU of vitamin D, 100-140 g of MgSO4, 2-3 g of FeSO4, 8-9 g of CuSO4, 9.5-10.5 g of MnSO4, 0.05-0.2 g of KI, and 0.15-0.25 g of CoCl2.

7. The feed composition according to any one of claims 1 to 6, characterized in that, The feed additives include β-carotene, vitamin A or its derivatives, vitamin E or its derivatives, yeast selenium, and emulsifiers; Preferably, the feed additive further includes maltodextrin; Preferably, the feed additive comprises the following components in parts by weight: 45-75 parts of β-carotene, 25-55 parts of vitamin A or its derivatives, 120-200 parts of vitamin E or its derivatives, 360-640 parts of yeast selenium, 130-300 parts of maltodextrin, and 10-40 parts of emulsifier. Preferably, the emulsifier is at least one selected from sorbitan fatty acid esters, bile salts, and lecithin; Preferably, the feed additive is a coated granule.

8. The feed composition according to any one of claims 1 to 7, characterized in that, In the feed composition, the dry matter mass ratio of roughage, concentrate and feed additive is (50~54):(42~48):(2~4).

9. Any of the following applications of the feed composition according to any one of claims 1 to 8: (1) Application in dairy cow feeding; (2) Application in increasing the vitamin A content in raw milk, improving the taste and flavor of milk and / or improving the stability of vitamin A in milk; (3) Application in the preparation of dairy cow feed.

10. A dairy cow feed, characterized in that, The feed comprises the feed composition according to any one of claims 1 to 8.

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