Effect of Mating on the Luteinizing Hormone Surge in the Pig

Abstract

Twenty-eight cannulated crossbred gilts were assigned to one of four treatments: natural mating, artificial insemination (AI, whole semen), AI (seminal plasma) or control (nonmated). Blood samples were collected four times daily (0800, 1200, 1600 and 2000 hr) on the day before standing estrus, the day of the onset of standing estrus and the first day after the onset of standing estrus. Thereafter, blood samples were collected once daily (1200 hr) until 15 days postestrus. Analysis of luteinizing hormone (LH) in the plasma revealed similar concentrations for all groups on the day of estrus, but higher (P less than .05) values for naturally mated gilts the following morning. Mean concentrations of LH on the first day after the onset of standing estrus were higher (P less than .01) for the mated gilts (2.75 +/- .54 ng/ml) than for gilts in the AI whole semen (.89 +/- .10 ng/ml), AI seminal plasma (1.02 +/- .13 ng/ml) and control groups (.92 +/- .11 ng/ml). Concentration of LH in the plasma of pregnant gilts tended to be higher after day 9. These results suggest that coitus may prolong the LH surge.

LH profile and advancement of ovulation after transcervical infusion of seminal plasma at different stages of oestrus in gilts

“…Natural mating shortens the interval between the onset of oestrus and ovula¬ tion in gilts (Pitkjanen, 1958;Signoret et al, 1972). This has been explained by the stimulatory effect of copulation (Ziecik et al, 1981;Kirsch et al, 1985) and by specific components of boar seminal plasma (Seglin'sh and Brutgans, 1981;Claus, 1989;Weitze et al, 1990). Previous studies that used the single uterine horn infusion technique with the contralateral uterine horn as the untreated control horn (Mariensee model, Jungblut et al, 1991) and sonographic monitoring of ovaries showed that infusion of seminal plasma at the onset of oestrus provoked ovulation in the ipsilateral ovary of the treated horn 10.7 h earlier than in the contralateral ovary.…”

The Effect of Repeated Mating at Short Intervals on Reproductive Performance of Gilts

“…These results might be explained in part by the research of Randel et al (1973), who reported that cervical and clitoral stimulation caused an earlier preovulatory LH surge and ovulation in cattle. Also, Ziecik et at. (1981) suggested that natural mating may prolong the LH surge in the pig.…”

“…Accepted January 6, 1985 as pigs. Signoret et al (1972) and Ziecik et al (1981) reported that copulation reduced the duration of ovulation in the pig. These results might be explained in part by the research of Randel et al (1973), who reported that cervical and clitoral stimulation caused an earlier preovulatory LH surge and ovulation in cattle.…”

Letter to the Editor

“…But before even mentioning any quick fix, like adding estradiol to the suspended semen, one should step back and ask why we are confronted so quickly with an aging oocyte. Evidence has been accumulating over several decades that some ungulates, especially sheep, pig and cattle are facultative induced ovulators: mating during the first half day of standing heat accelerates the occurrence of the preovulatory LH peak and of ovulation(s) (Signoret et al 1972;Jochle 1973;Jlichle 1975;Ziecik et al 1981). As with induced ovulators, this allows for a synchronization of the chain of events involving male and female gametes, designed to guarantee a high level of fertilization and of pregnancies.…”