In order to explore the dynamic changes of metabolites in goat milk during different lactation periods, the differential metabolites in milk from Guanzhong dairy goats at the peak and late lactation stages were investigated by ultra-high performance liquid chromatography-quadrupole electrostatic field orbitrap mass spectrometry (UPLC-QE-MS). A total of 90 differential metabolites were identified using P < 0.05, variable importance in the projection (VIP) > 1.00, and fold change (FC) > 2 or < 0.5 as criteria. Compared with late-lactation milk, 50 differential metabolites were up-regulated and 40 down-regulated in peak-lactation milk. Metabolic pathway analysis showed that these differential metabolites were significantly correlated with the biosynthesis of secondary bile acids. According to the VIP, uridine diphosphate-N-acetylglucosamine and phosphatidylethanolamine (PE, 12:0/22:2(13Z,16Z)) could be considered as potential biomarkers for the differential changes of milk metabolites from Guanzhong dairy goats during the two lactation periods, but this needs further research to be confirmed.
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Open Access
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Open Access
Basic Research
Issue
To understand the differences in steroid hormone contents between goat and cow milk at different lactation stages.
The contents of steroid hormones in goat and cow milk at different lactation stages were investigated using ultra-high liquid chromatography-mass spectrometry (UPLC-MS). Gradient elution was performed using 0.5 mmol/L ammonium fluoride aqueous solution as mobile phase A and methanol as mobile phase B at a flow rate of 0.3 mL/min, and the target analytes were qualitatively and quantitatively detected using an electrospray ionization (ESI) source in the multiple reactions monitoring (MRM) mode.
A total of 11 steroid hormones, 17α-hydroxyprogesterone, 17α-pregnenolone, epi-testosterone, pregnenolone, progesterone, androstenedione, testosterone, estradiol, estrogen, cortisol, and cortisone, were detected from goat and cow milk samples. At the early lactation stage, the contents of 17α-hydroxyprogesterone, estrogen and cortisol showed significant differences between goat and cow milk (P < 0.05), and the contents of progesterone and progesterone showed extremely significant differences (P < 0.01); at the full lactation stage, significant differences in the contents 17α-hydroxyprogesterone, 17α-pregnenolone, androstenedione, and cortisone (P < 0.05), and extremely significant differences in the contents of progesterone and pregnenolone were found (P < 0.01); at the late lactation stage, significant differences in the contents of 17α-hydroxyprogesterone, androstenedione, estrogen, and cortisol (P < 0.05) were observed as well as extremely significant differences in the content of 17α-hydroxypregnenolone, pregnenolone, and progesterone (P < 0.01).
The differences in steroid hormone contents between goat and cow milk may be due to different pregnancy status.
Open Access
Research Article
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In order to identify and analyze the metabolites of colostrum differences between high yielding and low yielding Guanzhong dairy goats from metabolomics point of view. Six high-yielding (milk yield (3.68 ± 0.57) kg/d) and six low-yielding (milk yield (1.17 ± 0.64) kg/d) Guanzhong dairy goats of similar age, litter size, body weight, and days of lactation (2nd day postpartum) were selected. The colostrum samples were examined by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the results were combined with orthogonal partial least squares discriminant analysis (OPLS-DA) and Student’s t-test. The metabolites were screened for differential metabolites based on the principle of variable importance in the projection (VIP) > 1, P < 0.05, and the differential metabolites were subjected to cluster analysis, significant difference screening, and enrichment of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results showed that 95 differential metabolites were screened from the colostrum of Guanzhong dairy goats in the two groups, and the clustering heatmap showed that 9 of the top 50 differential metabolites were the most abundant in relative terms. The metabolites with significantly increased content in the colostrum of Guanzhong dairy goats in the high-yield group were D-alanine-D-serine, α-lactose, isoflavoprotein 2”-(6’-p-coumaroylglucoside), D-maltose, pravastatin, and diketoglucuronic acid, whereas the differential metabolites with relatively decreased content were taurocholate, L-carnitine, and thiamphenicol A. KEGG pathways enrichment analysis identified 8 potential metabolic pathways The results of this experiment provide a theoretical basis for the subsequent analysis of the mechanism of milk production traits in dairy livestock and the selection and breeding of high-yielding dairy goats.
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