Abstract :
The objective of this study was to characterize the vaginal bacterial flora and subsequent
pregnancy rates after AI in sheep subjected to 4 different estrous synchronization regimes
– the use of two intravaginal devices (silicone or polyurethane sponges), and two different
treatment periods (7 or 14 days). Twenty-one multiparous Texel ewes were randomly allocated
to 4 treatment groups during the breeding season. In the ewes from Group I (n = 6) and
Group II (n = 5), a polyurethane sponge containing 60mgMAP was inserted in the vagina for
a period of 7 or 14 days, respectively. In the ewes of Group III (n = 5) and Group IV (n = 5), an
intravaginal progesterone releasing insert (IVP4) containing 160mg of progesterone in an
inert silicone device, was inserted for 7 or 14 days, respectively. At device withdrawal, each
ewe was treated with 200 IU eCG i.m. Standard bacteriological procedures were performed
on vaginal mucus samples obtained before the introduction of the devices, at device withdrawal
and on the day of AI in all groups. Estrus was recorded with the aid of vasectomized
rams every 12 h, and AI was performed 52–54 h after device withdrawal, using fresh semen.
The intervals between device withdrawal and estrus were: Group I: 56.4±21.5 h; Group
II: 42.0±33.9 h; Group III: 51.6±21.5 h; Group IV: 37.2±10.7 h, while the pregnancy rates
were: Group I: 83.3%; Group II: 60.0%; Group III: 60.0%; Group IV: 60.0%. The pregnancy
rates and the interval between device withdrawal and the occurrence of estrus did not differ
between treatments. The predominant bacterial flora population at device insertion was
mostly gram positive (G+) (90%) bacteria. The strains most frequently found were Bacilllus
sp., Staphylococcus sp. and Corynebacterium sp. Of the 19 isolates made at device removal,
79% were gram negative, with the Escherichia sp. being the most frequently isolated. At the
time of AI and regardless of the device used, the 14-day treatment group presented an initial
gram positive bacterial flora, while the 7-day groups presented gram negative flora (82%).
It could be concluded that the use of intravaginal devices, regardless of their composition
(silicone or polyurethane), may generate changes in the normal vaginal bacterial flora of
the vaginal mucus. These changes did not reflect on the subsequent fertility. The use of
intravaginal devices should however include the adoption of strict hygiene procedures, to
minimize the growth of bacterial flora.
