Porcine Follicle-Stimulating Hormone Treatment of Gilts During an Altrenogest-Synchronized Follicular Phase: Effects on Follicle Growth, Hormone Secretion, Ovulation, and Fertilization1,2

Porcine FSH (SUPER OV®) , contain- follicles, respectively, on d 7 were as follows: saline (17, .7), eCG (43, .9), FSH14/21 (15, .6), FSH28 (12, 16), and FSH28+hCG (32, 21). Plasma FSH concen- trations were at least threefold higher ( P < .05) in gilts treated with FSH than in gilts not treated with FSH. The percentage in estrus was higher ( P < .05) for saline- and eCG-treated gilts (100 and 87%, respectively) than for FSH-treated gilts (53%). Proportion of FSH28+hCG-treated gilts with fertilized ova ( 27%) was lower than for other groups (79 to 100%). In summary, the 3-d high dose FSH treatment (FSH28 and FSH28+hCG) during an altrenogest- synchronized follicular phase increased the number of potentially ovulatory follicles, but this potential benefit was not realized because many follicles failed to ovulate. The co-injection of low doses of hCG (FSH28+hCG) increased the ovulation rate and estradiol secretion but reduced ova recovery and fertilization rate compared with eCG and the other FSH treatments.