Optimised Method for Short-Chain Fatty Acid Profiling of Bovine Milk and Serum.

Cheng Li,Jennie Pryce,Zhiqian Liu,Carolyn Bath,Leah Marett,Simone Rochfort

doi:10.3390/molecules27020436

Cheng Li, Jennie Pryce + Show 4 more

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https://doi.org/10.3390/molecules27020436

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Abstract

Short-chain fatty acids (SCFA, C2-C5) in milk and serum are derived from rumen bacterial fermentation and, thus, have the potential to be used as biomarkers for the health status of dairy cows. Currently, there is no comprehensive and validated method that can be used to analyse all SCFAs in both bovine serum and milk. This paper reports an optimised protocol, combining 3-nitrophenylhydrazine (3-NPH) derivatisation and liquid chromatography-mass spectrometry (LC-MS) analysis for quantification of SCFA and β-hydroxybutyric acid (BHBA) in both bovine milk and bovine serum. This method is sensitive (limit of detection (LOD) ≤ 0.1 µmol/L of bovine milk and serum), accurate (recovery 84–115% for most analytes) and reproducible (relative standard deviation (RSD) for repeated analyses below 7% for most measurements) with a short sample preparation step. The application of this method to samples collected from a small cohort of animals allowed us to reveal a large variation in SCFA concentration between serum and milk and across different animals as well as the strong correlation of some SCFAs between milk and serum samples.

Highlights

Bovine milk and serum lipidomic studies are important for the dairy industry, as some of the lipids of milk and serum are associated with the physical properties and nutritional value of dairy products, and they have potential value for predicting the health status and fertility of dairy cows [1,2]
By optimising derivatisation parameters and reversed phase liquid chromatography-mass spectrometry (LC-MS) (RP-LC-MS) analysis, we show that our method is simple and reliable for SCFA analysis in both milk and serum samples
Each or 28~55 μmol/L) (A) and endogenous SCFA extracted from raw milk (B) and serum (C)

Summary

Introduction

Bovine milk and serum lipidomic studies are important for the dairy industry, as some of the lipids of milk and serum are associated with the physical properties and nutritional value of dairy products, and they have potential value for predicting the health status and fertility of dairy cows [1,2]. Some lipids in milk are transferred from the blood, while others are from de novo synthesis in the mammary gland [3]. In addition to triglycerides and phospholipids, blood and milk contain non-esterified or free fatty acids (FA), including short-chain FA (SCFA, C2-C5) or volatile. C2, C3 and C4 are precursors for de novo synthesis of FA in the mammary gland [4]. Ruminal SCFA are important signalling molecules, regulating a variety of physiological functions of the rumen [6]. Diet appears to have a large influence on this as it can alter the rumen microbiome, the SCFA profile produced by these microorganisms and even subsequent changes in ruminal pH, which can affect SCFA absorption in blood [7,8]. Heat stress (along with reduced feed intake) results in reduced de novo FA, including some

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