Differences in the bovine milk whey proteome between early pregnancy and the estrous cycle

ABSTRACT: As current bovine pregnancy detection methods are not reliable until at least day 28 post artificial insemination (AI), commercial interest exists for the discovery of novel biomarkers of pregnancy which could reliably detect pregnancy status at or before day 21 of pregnancy. This would allow producers the opportunity to rebreed at the next oestrus event. Therefore, the objective of the present study was to use liquid chromatography tandem mass spectrometry (LC-MS/MS) to perform a global, label-free, proteomics study on (i) whole milk whey and (ii) extracellular vesicle (EV) enriched milk whey samples, from day 21 of pregnancy and day 21 of the oestrous cycle, in order to identify potential protein biomarkers of early pregnancy. The oestrous cycles of 10 dairy cows were synchronised, they went through one (control) oestrous cycle and these cows were artificially inseminated during the following oestrous. These cows were confirmed pregnant by ultrasound scanning. Milk whey samples were collected on day 21 of the oestrous cycle and on day 21 post AI. A Q-Exactive was used to analyse whole milk whey samples and EV enriched milk whey samples by LC-MS/MS and subsequent analyses of the label-free quantitative data was performed in MaxQuant and Perseus. Four proteins (APOB, SPADH1, PLIN2 and LPO) were differentially expressed between the proteomes of whole milk whey from day 21 of pregnancy and day 21 of the oestrous cycle (P<0.05). Ten proteins (PIGR, PGD, QSOX1, MUC1, SRPRA, MD2, GAPDH, FOLR1, GPRC5B and HHIPL2) were differentially expressed between the proteomes of milk whey from day 21 of pregnancy and day 21 of the oestrous cycle (P<0.05). These proteins are potential milk whey biomarkers of early pregnancy; however, the small fold change differences in their abundance between samples obtained during early pregnancy and during oestrous will restrict their use in a pregnancy diagnosis test.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Bos Taurus (bovine)

SUBMITTER: Dayle Johnston  

LAB HEAD: Michael Diskin

PROVIDER: PXD007927 | Pride | 2018-04-23

REPOSITORIES: Pride