This thesis describes several boar stimuli in their potency to elicit estrous behavior and their potency to affect uterine contractility. With different levels of boar stimuli, onset of estrus can be recorded at different time points relative to ovulation, depending on the change in responsiveness of sows to the stimuli. However, the onset of estrus recorded in such ways, as well as the change in responsiveness recorded by using different stimuli to induce estrous behavior, appeared to be bad predictors for the time of ovulation. Time of ovulation is important for the success of insemination. The use of a back pressure test in the presence of a boar appeared to be most appropriate for detection of estrus, as with lower levels of boar stimuli the chance of not detecting estrus increases, and higher levels of stimuli did not add to the efficiency of estrus detection due to habituation. Uterine contractility is increased during estrus and is important for sperm transport, as suppression of uterine contractility reduces fertilisation rate. Stimulation of uterine contractility to a high degree on the other hand, can obstruct the uptake of the inseminate and increase the reflux of semen. Presence of a boar is more potent than 5-androstenon or tactile stimuli in inducing the release of oxytocin and in stimulating uterine contractility. Moreover, boar presence selectively stimulates uterine contractility only in sows that have a below average uterine contractility, and might therefore be an appropriate way of stimulating uterine contractility during insemination.
|Qualification||Doctor of Philosophy|
|Award date||4 Dec 2001|
|Place of Publication||S.l.|
|Publication status||Published - 2001|