Ovarian activity in gilts including some characteristics of a native breed

Follicular development and ovulation result from a coordinated change in the balance of gonadotropins (LH, FSH) and steroids (progesterone, estradiol) during the estrous cycle. Emergence of ovulatory follicles is associated with decreased secretion of progesterone in the absence of significant change of LH concentration. Unlike what occurs in cattle, there is only one wave of follicular development during the porcine estrous cycle. The recruitment of these follicles is initiated by the postovulatory FSH surge. Preovulatory follicles grow and differentiate in an environment of declined FSH concentrations. Based on this physiological conditions there are two possible strategies to influence follicular development. Compared to the number of follicles destined to ovulate (about 12-18/gilt) the potential of recruited follicles is more than 2- to 3-fold higher. The first strategy includes the application of gonadotropins, i.e. PMSG, which has both a definite FSH and a balanced LH activity, during the follicular phase to influence the number of selected follicles. The second strategy comprises the application of porcine FSH during the early luteal phase to support the postovulatory FSH surge to increase follicle recruitment. Aboriginal and endangered swine breeds with different genetic, commercial or national value have been more and more in the focus of interest. Mangalica is a value nativ pig breed adapted to extensive climate and housing conditions in Hungary. Compared to modem breeds, Mangalica has a poor reproductive ability. Fecundity in different swine breeds may have its origin in ovarian reactivity. To propagate the very small population by means of biotechnical methods, the ovarian reactivity was analyzed after estrous synchronization with Regumate(R) and stimulation with different treatments of PMSG. The application of 1000 and 1250 IU PMSG resulted in a significant higher number of ovulation (24.2+/-2.5 and 21.0+/-2.9, p=0.01) compared to 750 IU PMSG and to untreated sows (13.7+/-3.1 and 11.5+/-2.1, respectively). Embryos recovered at the blastocyst stage were successful used in a embryo transfer program. Unsufficient ovarian reactivity seems not to be the reason of low fertility in Mangalica.