(141) Vaginal Microbiome Changes Associated with Fertility in Beef Cows Subjected to a 14-day Implant Synchronization Protocol

Thursday, July 31, 2025

8:30 AM - 9:30 AM EDT

Location: Marquis Ballroom 6-10

Author(s)

Riley J. Puck, MS

Masters Student
South Dakota State University
Isanti, Minnesota, United States

Abstract Authors:

Riley J Puck1; Cody J. Williams1; Silvio A. Isler2; Kendal L. Green1; Felipe O. Pedro2; Hunter C. Haberman1; Benoit St-Pierre1; Jessica N. Drum1

Department of Animal Science, South Dakota State University, Brookings, South Dakota

Department of Animal Science, Mato Grosso do Sul State University, Aquidauana, Brazil

Abstract Text: Synchronization protocols with progesterone implants for 7 days have been shown to contribute to shifts in microbial populations. However, these alterations have yet to be characterized when utilizing pre-synchronization strategies that extend the implant time. The objective of this study was to determine the diversity and composition of vaginal bacteria in pregnant (P) vs. open (OP) beef cows submitted to a 14-day implant synchronization protocol. We hypothesized that bacterial communities would change regarding pregnancy status, with increased variability at the implant removal compared to the beginning of the protocol. Beef cows (n = 133, 4.32 ± 2.41 years old) were enrolled in a 7 & 7 estrus synchronization protocol across two farms. Cows were swabbed with a double-guarded culture swab (Jorgensen Laboratories, CO) by spinning 15 times on the cranial vagina on days (d) 0, and 14 of the protocol. On d14, cows also received an estrus detection patch (Estrotect™, Rockway INC, WI). Estrus detection was performed every 6h during the daytime, starting 24h after CIDR pull. Cows underwent AI 12-18h after heat detection patches were activated. Cows that expressed heat 54h and up after CIDR removal were bred at the fixed time (66 ± 2 h) and received a concomitant GnRH injection. Pregnancy diagnosis was performed by ultrasonography d32 post-AI. Cows were grouped post-hoc based on pregnancy status, then 12 P and 12 OP cows were randomly selected for microbiome analysis. Microbiome data were generated from Illumina MiSeq (2x300) sequencing of PCR amplicons targeting the V1-V3 region of the 16 rRNA gene. Sequences were analyzed using custom Perl scripts and publicly available software (Mothur v.1.40, RDP classifier, and NCBI Blast). Analysis of species-level operational taxonomic units (OTUs) was performed on the samples from d0 and d14. Statistical analysis of microbial abundances used Kruskal-Wallis’s and Pairwise Wilcox test. The topmost abundant OTU, RP1-00038, closely related to Citrobacter gillenii (99.43%), decreased in abundance by d14 (OP_d0=68.6%, OP_d14=9.9%, P_d0=71.6%, P_d14=5.5%; P</span>≤0.00003), but abundance did not differ between status within the same day (P >0.05). Significant differences were also found when comparing statuses and (OP_d0=68.6% vs P_d14=5.5%; P=0.000004, P_d0=71.6% vs OP_d14=9.9%; P=0.00003). OTU RP4-08239 was closely related to Helcococcus ovis (99.60%), and its abundance increased from d0 to d14 by status (OP_d0=0.6%, OP_d14=18.4%, P_d0=0.5%, P_d14=24.1%; P <0.0001); while abundance did not differ between statuses on the same day (P >0.05), there were significant interactions of status and day (OP_d0=0.6% vs P_d14=24.1%, P=0.00002; P_d0=0.5% vs OP_d14=18.4%, P=0.000004). OUT RP4-12494 was closely related to Fusobacterium necrophorum (99.39%), and its abundance increased between d0 and d14 by status (OP_d0=0.2%, OP_d14=12.5%, P_d0=0.1%, P_d14=10.8%; OP, P=0.031; P</span>, P=0.029); while abundance did not differ between status on the same day (P >0.05), status and day (OP_d0=0.2% vs P</span>_d14=10.8% & P</span>_d0=0.1% vs OP_d14=12.5%; P=0.029). These results indicate shifts in the vaginal microbiome population across a 14-day implant synchronization protocol. Future research will be required to determine whether vaginal health and fertility may be impacted.