1. Investigación

The vaginal microbiota plays an important role in the health of dairy cattle, and it could be manipulated for the prevention and treatment of reproduction-related infections. The present study profiles and compares the vaginal microbiota of healthy dairy heifers during the estrous cycle focusing the results in follicular (estrus) and luteal (diestrus) phases using 16S rRNA sequencing of the V3–V4 hypervariable region. Twenty 13–16-months-old virgin dairy heifers from a single farm were included in this study. Vaginal swabs and blood samples were obtained during estrus (6–8 h before artificial insemination) and diestrus (14 days after insemination). Estrus was evaluated by an activity monitoring system and confirmed with plasma progesterone immunoassay. Results showed that the taxonomic composition of the vaginal microbiota was different during the follicular and luteal phases. At the phylum level, the most abundant bacterial phyla were Tenericutes, Firmicutes, and Bacteroidetes which comprised more than 75%of the vaginal microbiota composition. The next more abundant phyla, in order of decreasing abundance, were Proteobacteria, Actinobacteria, Fusobacteria, Epsilonbacteraeota, and Patescibacteria. Together with Tenericutes, Firmicutes, and Bacteroidetes represented more than 96% of the bacterial composition. Ureaplasma, Histophilus, f_Corynebacteriaceae, Porphyromonas, Mycoplasma, Ruminococcaceae UCG-005, were the most abundant genera or families. The results also showed that the vaginal microbiota of dairy heifers was non-lactobacillus dominant. The genus Lactobacillus was always found at a low relative abundance during the estrous cycle being more abundant in the follicular than in the luteal phase. Despite more research is needed to explore the potential use of native vaginal microbiota members as probiotics in dairy heifers, this study represents an important step forward. Understanding how the microbiota behaves in healthy heifers will help to identify vaginal dysbiosis related to disease.

Sheep estrous synchronization is mainly based on progestagen-impregnated sponges which could cause vaginitis. Several species of Lactobacillus used as probiotics are commonly used in the treatment or prevention of urogenital infections in humans. However, no studies have been performed to analyze the potential use of probiotics to prevent urogenital infections in sheep. A randomized controlled clinical trial was conducted with 21 one-year-old ewes to develop a model of probiotic infusion in vaginal sponges in order to study their influence in ewe’s vaginal microbiota, general health status, fertility and prolificity. Synchronization of estrus was based on intravaginal sponges for 14 days. Bacterial communities (Enterobacteriaceae and lactic acid bacteria) were highly fluctuating over time and between animals. The safety of probiotic infusion (mix of Lactobacillus spp. 60% L. crispatus, 20% L. brevis and 20% L. gasseri) in the vagina of healthy ewes was firstly confirmed. Neutrophils were observed in 80% (8/10) of the control ewes compared to 36% (4/11) of the ewes in the probiotic group 2 days after sponge removal (p = 0.056). Fertility in the control and probiotic groups was 60% (6/10) and 91% (10/11), respectively p = 0.097. These results suggest that Lactobacillus spp. infusion in the ewe’s vagina does not affect general health status or fertility.

Lactic acid bacteria (LAB) dominate human vaginal microbiota and inhibit pathogen proliferation. In other mammals, LAB do not dominate vaginal microbiota, however shifts of dominant microorganisms occur during ovarian cycle. The study objectives were to characterize equine vaginal microbiota in mares by culture-dependent and independent methods and to describe its variation in estrus and diestrus. Vaginal swabs from 8 healthy adult Arabian mares were obtained in estrus and diestrus. For culture-dependent processing, bacteria were isolated on Columbia blood agar (BA) and Man Rogosa Sharpe (MRS) agar. LAB comprised only 2% of total bacterial isolates and were not related to ovarian phases. For culture-independent processing, V3/V4 variable regions of the 16S ribosomal RNA gene were amplified and sequenced using Illumina Miseq. The diversity and composition of the vaginal microbiota did not change during the estrous cycle. Core equine vaginal microbiome consisted of Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria at the phylum level. At the genus level it was defined by Porphyromonas, Campylobacter, Arcanobacterium, Corynebacterium, Streptococcus, Fusobacterium, uncultured Kiritimatiaellae and Akkermansia. Lactobacillus comprised only 0.18% of the taxonomic composition in estrus and 0.37% in diestrus. No di erences in the relative abundance of the most abundant phylum or genera were observed between estrus and diestrus samples.

The present study supports that short-term (7-days) protocols based on progestagen-impregnated sponges and progesterone-loaded CIDRs are equally effective to induce ovulatory response in sheep. There were no significant differences in the onset of estrus behavior (32.0±6.0 and 33.8±4.0h after device withdrawal for sponges and CIDRs, respectively; p > .05) and preovulatory LH discharge (5.1 ± 2.1 and 5.8 ± 3.3h after onset of estrus behavior for sponges and CIDRs, respectively; p > .05). These features are similar to previously described for classical long-term (12-14 days) treatments. Hence, short-term CIDR-based protocols may be implemented using the same time-intervals for insemination than sponge-based and long-term protocols.

The present study indicates that short-term progestagen-based protocols for synchronization of estrus and ovulation in sheep involving 7 days of progestagen insertion with administration of prostaglandin F2α at either insertion or removal of the progestagen sponge resulted in 80–90% fertility during the breeding season, while a classical long-term protocol of 14 days of progestagen insertion resulted in 77% fertility. During the non-breeding season, fertility was significantly higher for the 7-day protocol with prostaglandin administration at sponge insertion (79.2%) and for the 14-day protocol (80%) than for the 7-day protocol with prostaglandin administration at sponge removal (59.1%; P = 0.018). Prolificacy, in contrast, varied significantly with genotype, being higher in prolific breeds, but it did not vary with progestagen protocol or breeding season. These results suggest that short-term progestagen-based treatments can provide similar reproductive efficiency as long-term treatments, which may help practitioners reduce welfare and health issues while maintaining productivity.