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Follicle maturation, ovulation rate and early embryonic development in pigs as influenced by natural and induced changes in gonadotropins during the estrous cycle
Abstract
The first of three experiments evaluated the effects of FSH suppression during late luteal and early follicular phases of the estrous cycle on follicle recruitment, maturation and ovulation rate. Gilts were administered 5 ml of steroid-reduced pFF from d 10 through d 14 and luteolysis was induced on d 12. Concentrations of FSH were reduced during pFF treatment compared to controls. A small increase in FSH was observed on d 15 after last pFF injection on d 14. Treatment with pFF reduced numbers of medium follicles compared to controls on d 13 and 15 but not on d 17. Numbers of large follicles were reduced on d 17 from pFF but ovulation rate at post-treatment estrus was not affected. Experiment 2 characterized differences in FSH, LH, ratio of FSH:LH, E$\sb2,$ P$\sb4$ and inhibin profiles during the estrous cycle in gilts differing in ovulation rate (OR). Concentrations of FSH were elevated throughout the estrous cycle in high ovulating gilts expressing a 20 d estrous cycle compared to low OR gilts. High OR gilts that expressed 25 d estrous cycles had elevated FSH only during the late luteal and early follicular phases. No differences were detected in mean LH, LH pulse characteristics or E$\sb2,$ but P$\sb4$ (luteal phase), inhibin (follicular phase) and ratio of FSH:LH (luteal phase) were elevated in high OR gilts. Experiment 3 developed a dose and treatment regimen of FSH-P that induced superovulation and compared its effectiveness against PMSG for increasing ovulation rate, numbers of embryos and synchrony of embryo development on d 10. Treatment with FSH-P (6 i.m. injections of 1.6 AU/8 h beginning on d 13) increased OR and numbers of embryos on d 10 compared to controls but incidence of estrus and ovulation were reduced. PMSG (1200 IU) also induced superovulation and increased numbers of embryos. Within litter variation in embryo size was comparable for control and FSH-P gilts but was increased in gilts treated with PMSG.
Subject Area
Anatomy & physiology|Animals|Veterinary services|Zoology|Livestock
Recommended Citation
Knox, Robert Victor, "Follicle maturation, ovulation rate and early embryonic development in pigs as influenced by natural and induced changes in gonadotropins during the estrous cycle" (1992). ETD collection for University of Nebraska-Lincoln. AAI9225474.
https://digitalcommons.unl.edu/dissertations/AAI9225474