Effects of relaxin administration in early gestation or prior to mating on uterine length and fetal survival in gilts

• Published in: Biology of reproduction Vol. 52; no. 6; pp. 1389 - 1394
• Main Authors: Zaleski, H.M. (University of Hawaii, Honolulu, HI.), Winn, R.J, Jennings, R.L, Dziuk, P.J, Sherwood, O.D
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-06-1995
• Subjects: Animals; Biological and medical sciences; CERDAS; CICLO ESTRAL; CYCLE OESTRAL; Estradiol - pharmacology; ESTROGENOS; Female; FETO; Fetus - drug effects; FOETUS; Fundamental and applied biological sciences. Psychology; GESTACION; GESTATION; Gestational Age; Hormone metabolism and regulation; LARGURA; LONGUEUR; MORT DU FOETUS; MUERTE FETAL; OESTROGENE; Organ Size - drug effects; Ovariectomy; PESO; POIDS; Pregnancy. Parturition. Lactation; PROGESTERONA; PROGESTERONE; Progesterone - pharmacology; Relaxin - pharmacology; RELAXINA; RELAXINE; SUPERVIVENCIA; SURVIE; Swine; Time Factors; TRUIE; UTERO; UTERUS; Uterus - anatomy & histology; Uterus - drug effects; Vertebrates: reproduction; Relaxine; Embryonic development; Size; Ovarian hormone; Follicular phase; Pig; Vertebrata; Mammalia; Uterus; Female genital system; Female; Fetus; Early pregnancy; Artiodactyla; Estrous cycle; Morphometry; Ungulata
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod52.6.1389

The objective of this research was to determine the effect of administration of porcine relaxin to gilts during early gestation, or during the follicular phase of the estrous cycle immediately preceding mating, on the length of the uterus and consequently the number of surviving fetuses. Experiment 1 datermined the individual and combined effects of 10 days of administration of relaxin (0.5 mg, 4 times daily), estradiol benzoate (1 mg, 2 times daily), and progesterone (50 mg, 2 times daily) on uterine wet weight and length in 58 ovariectomized 8-mo old pubertal gilts. Relaxin alone had no effect on either uterine length or wet weight. Estrogen increased uterine wet weight, and this effect was augmented by relaxin. Progesterone increased uterine length, and this effect was augmented by estrogen. Combined treatment with progesterone, estrogen, and relaxin increased both uterine length and wet weight maximally. Experiment 2 determined tbe effects of relaxin administration in early gestation or prior to mating on uterine length and fetal survival in 75 unilaterally ovariectomized-hysterectomized gilts. Relaxin (0.5 mg, 4 times daily) was administered during three treatment periods, and uteri were collected on Day 40 of gestation. In this study, relaxin administration from Days 11 to 20 of gestation reduced the number of live fetuses (p = 0.01) and percentage survival (p = 0.01) and resulted in shorter uterine length (p = 0.01) and lower uterine wet weight (p = 0.03) than in controls, but did not affect length of uterus per fetus or uterine dry weight. Relaxin administration from Days 22 to 31 of gestation did not influence fetal survival, uterine length, uterine length per fetus, uterine wet weight, or uterine dry weight. Relaxin administration from Days 11 to 20 of the estrous cycle followed by mating at the subsequent estrus reduced the number of live fetuses (p = 0.03), reduced the percentage survival (p = 0.03), increased the occupied length of uterus per live pig