关键词: 关键词：液相色谱-串联质谱, 山羊乳和牛乳, 泌乳期, 类固醇激素, 代谢差异

Abstract: Abstract: 【Purpose】To understand the metabolic differences in steroid hormone content between goat milk and cow milk at different lactation stages.【Method】Select 6 Guanzhong dairy goats and 6 Holstein cows each in the early lactation stage (2 days of lactation), peak lactation stage (90 days of lactation), and late lactation stage (220 days of lactation) with good health and consistent feeding conditions. Detection of steroid hormone levels in milk at different lactation stages by liquid chromatography-mass spectrometry (LC-MS/MS). The chromatographic conditions for detection were as follows: mobile phases A (ammonium fluoride aqueous solution) and B (methanol), positive ion spray voltage 5500V; The negative ion spray voltage is -4500 V, the ion source temperature was 550 ℃, and the column temperature was 45 ℃; Quantitative analysis using the multiple reaction detection (MRM) mode of triple quadrupole mass spectrometry. Combined with negative ion mode detection of electric spray ion source. 【Results】The results showed that a total of 9 types of steroid hormones were detected from goat milk and cow milk at different lactation stages, using 24 different targets as reference. These hormones were 17α-hydroxypregnenolone, 17α-pregnenolone, 17-Epi-Testosterone, progesterone, androstenedione, testosterone, estrogen, cortisol, and cortisol, respectively. The hormones with significant differences in content between goat milk and cow milk during the early lactation stage are 17a hydroxypregnenolone, estrogen, and cortisol (P<0.05); The hormones with significant differences in content during the peak lactation period were 17a hydroxyprogesterone, progesterone, cortisol, and cortisol (P<0.05); The hormones with significant differences in content between goat milk and cow milk in the late lactation stage are 17a hydroxypregnenolone, progesterone, and testosterone cortisone (P<0.05). 【Conclusion】The difference in steroid hormone levels between goat milk and cow milk may be due to differences in pregnancy status, the research results provide theoretical basis for the design of functional dairy products and the prevention of steroid hormone metabolism diseases.

Key words: Keywords: Liquid chromatography tandem mass spectrometry(UPLC-MS/MS), Lactation period, Goat milk, Milk, Steroid hormones