Circulating microRNA Profiles during the Bovine Oestrous Cycle

Area of Science:

• Veterinary Reproductive Biology
• Molecular Biology
• Biomarker Discovery

Background:

• Oestrus detection in dairy herds is often inaccurate, leading to reduced productivity and economic losses.
• MicroRNAs (miRNAs) are key gene regulators and circulating miRNAs can serve as biomarkers for physiological states.
• Previous research indicates miRNA profile changes during reproductive cycles.

Purpose of the Study:

• To investigate circulating microRNAs as potential biomarkers for oestrus detection in cattle.
• To identify specific miRNAs that change in abundance during the oestrous cycle.

Main Methods:

• Plasma samples were collected from Holstein-Friesian heifers across their oestrous cycle (Days 0, 8, 16).
• Small RNA populations were analyzed using Illumina sequencing and Qiagen PCR arrays.
• RT-qPCR was employed for validation and to assess additional relevant miRNAs.

Main Results:

• Four specific miRNAs (let-7f, miR-125b, miR-145, miR-99a-5p) showed significantly increased plasma levels during oestrus (Day 0).
• Plasma concentrations of these miRNAs increased up to 2.2-fold (P < 0.05) compared to other cycle days.
• Hundreds of isomiRs were identified, with their relative abundance in bovine plasma characterized.

Conclusions:

• Plasma microRNA profiles dynamically change throughout the bovine oestrous cycle.
• Circulating miRNAs hold promise as non-invasive biomarkers for detecting oestrus and assessing reproductive function in livestock.
• This research supports future development of accurate oestrus detection tools for dairy herds.