Vaginal Microbiota Changes During Estrous Cycle in Dairy Heifers

Area of Science:

• Veterinary Microbiology
• Ruminant Health
• Reproductive Biology

Background:

• The vaginal microbiota is crucial for dairy cattle reproductive health and can be targeted for infection prevention.
• Understanding the dynamic changes in the vaginal microbiota during the estrous cycle is essential for identifying healthy states and potential dysbiosis.

Purpose of the Study:

• To profile and compare the vaginal microbiota of healthy dairy heifers during the follicular (estrus) and luteal (diestrus) phases of the estrous cycle.
• To identify key bacterial taxa and assess the dominance of Lactobacillus species in the heifer vaginal microbiome.

Main Methods:

• 16S rRNA gene sequencing of the V3-V4 hypervariable region was used to analyze vaginal swabs from 20 heifers.
• Estrus was confirmed using an activity monitoring system and plasma progesterone levels.
• Samples were collected during estrus and diestrus phases of the estrous cycle.

Main Results:

• Significant differences in vaginal microbiota composition were observed between the follicular and luteal phases.
• Tenericutes, Firmicutes, and Bacteroidetes were the most abundant phyla, comprising over 96% of the total bacteria.
• The vaginal microbiota was non-Lactobacillus dominant, with Lactobacillus species present in low abundance, higher in the follicular phase.

Conclusions:

• The vaginal microbiota composition in dairy heifers varies significantly throughout the estrous cycle.
• The non-Lactobacillus dominant nature and specific bacterial genera identified provide a baseline for healthy heifer vaginal microbiome.
• Further research into native microbiota members could lead to probiotic applications for enhancing reproductive health in dairy cattle.