Reproductive management in sheep often involves estrus synchronization using intravaginal sponges. While the effects on adult ewes are known, the impact on nulliparous ewe lambs remains unclear. This study characterized the vaginal bacteria of 22 Latxa ewe lambs at three stages using 16S rRNA gene amplicon sequencing: baseline, after initial physical handling (hymen rupture), and after sponge removal. At baseline, the ewes hosted diverse bacterial communities, showing similarities to those found in the gut. However, the first physical exam and subsequent hormone treatment significantly altered this environment, reducing bacterial diversity and promoting opportunistic genera often associated with infertility, such as Trueperella. Surprisingly, despite this temporary microbial imbalance, the flock achieved an 89% pregnancy rate. These findings show that while standard reproductive protocols significantly disrupt the vaginal ecosystem of young ewes, the reproductive tract is sufficiently resilient to restore functionality and allow for successful conception via natural mating.

Read the full article in the Journal of Animal Science.