The main methods of checking for feed vitamins include the following

Microbiological method: A method of quantitative analysis that utilizes the growth dependence of certain microorganisms on specific vitamins. This method is simple, low cost and suitable for the determination of many water-soluble vitamins, such as vitamin B1, vitamin B2, vitamin B6, vitamin B12, niacin, pantothenic acid, folic acid and biotin.

High Performance Liquid Chromatography (HPLC): a method for separating and detecting different components in a mixture, with the advantages of high separation efficiency, fast analysis speed and high sensitivity. It is suitable for the determination of a variety of fat-soluble and water-soluble vitamins, such as vitamin A, vitamin D, vitamin E, vitamin K, vitamin C and so on.

Spectrophotometry: a method of quantitative analysis using the absorption characteristics of substances for specific wavelengths of light. This method is easy to operate, fast, and suitable for the determination of certain vitamins, such as vitamin A, vitamin B2, vitamin C, etc.

Rapid detection methods: These include visual inspection and simple chemical tests, such as rapid identification of Vitamin A, Vitamin E, Vitamin K3 and Vitamins B1 and B2 by the color change of the solution. These methods are usually used for rapid on-site testing.

The choice of these methods depends on the type of vitamin to be tested, the nature of the sample, and the accuracy and speed required. In practice, a combination of methods may be used to ensure the accuracy and reliability of the assay.