Intravaginal Device-Type and Treatment-Length for Ovine Estrus Synchronization Modify Vaginal Mucus and Microbiota and Affect Fertility

Abstract

Simple SummaryThis study examined the effects of different intravaginal device types used for estrous cycle management in sheep, and the timing of their insertion, on vaginal features (characteristics of vaginal mucus discharge, pH and microbiota) and fertility under field conditions.AbstractInduction and synchronization of estrus and ovulation in sheep is based on intravaginal progestagen-impregnated polyurethane sponges or progesterone-loaded silicon-based devices (CIDR), in either short- (6–7 days) or long-term (12–14 days) protocols. Bearing in mind that the use of intravaginal sponges in long-term protocols has been related to the presence of vaginitis at removal, we compared the effects of sponges and CIDRs, maintained during either 7 or 14 days, on vaginal features (characteristics of vaginal mucus discharge, pH and microbiota) and fertility under field conditions. Almost all the ewes treated with intravaginal sponges showed vaginal discharge at device withdrawal, which was purulent and/or bloody in around 15% and 80% of the females treated for 7 and 14 days, respectively. The vaginal pH and microbiota changed in both groups when compared to control sheep, especially in ewes treated for 14 days, which showed a pH value around 8 and a higher incidence of Salmonella spp. and Staphylococcus aureus. On the other hand, independently of the length of the treatment, only around 15–20% of the sheep treated with CIDRs evidenced vaginal discharge (p < 0.00005 when compared to sponge groups), and such discharge was scarce, clear, and showed no changes in vaginal pH and microbiota when compared to control sheep. Fertility yields were associated with vaginal features, being higher in both short-term treatments (75%) and the long-term CIDR-based treatment (70%) than in the long-term sponge-based treatment (45%).

Use of Probiotics in Intravaginal Sponges in Sheep: A Pilot Study

“…In the present study, no significant differences were observed in the total number of bacteria on T0 and on T-Estrus, but in the control group variance was higher during T-Estrus, which could suggest that intravaginal sponge altered the ewe's vaginal ecosystem dynamics and could increase instability during fertilization process. These results are in agreement with previous studies showing that intravaginal sponges are associated with abnormal discharges and vaginitis at sponge withdrawal [8]. Changes in the vaginal microbiota after long term progestagen treatment predispose to inflammatory and infectious processes which result in abnormal vaginal discharges [30].…”

“…Most protocols of estrous synchronization in ewes include the use of synthetic progestagens administered by intravaginal sponges for 12-14 days [1,2]. The use of intravaginal devices may generate retention of vaginal secretions and abnormal discharges at device withdrawal, which may create changes in the normal vaginal bacterial microbiota [3,4] and a lower fertilization rate [5][6][7][8]. These changes in vaginal microbiota could allow the growth of opportunistic pathogenic bacteria which can require antibiotic treatment [9,10].…”

Influence of Progesterone-Treatment Length and eCG Administration on Appearance of Estrus Behavior, Ovulatory Success and Fertility in Sheep

“…These alterations were later related to the prolonged time of treatment permanence, and these findings supported the use of short-term (5–7 days) progestative treatments [6,7,8]. Currently, short-term protocols are recognized to be equally as effective as long-term protocols for inducing estrus, ovulation, and fully functional corpora lutea [9], with lower incidence of vaginal infections [10] and higher fertility yields [11].…”

Onset of oestrus and periovulatory events in sheep exposed to 5 and 14 days of CIDR treatment with and without eCG

“…Short‐term protocols (5–7 days of progesterone insertion) are increasingly used since they are equally as effective as long‐term protocols for inducing ovulation and fully functional corpora lutea (Martinez‐Ros, Astiz, Garcia‐Rosello, Rios‐Abellan, & Gonzalez‐Bulnes, ), with lower incidence of vaginal infections (Martinez‐Ros, Lozano, et al, ) and higher fertility yields (Menchaca, Santos‐Neto, Cuadro, Souza‐Neves, & Crispo, ; Swellum, Alowaimer, & Abouheif, ).…”