Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Technical Abstract: Forty-three prepubertal gilts underwent unilateral hysterectomy-ovariectomy to reduce uterine capacity to evaluate effects of rpST on fetal and placental growth. Gilts were artificially inseminated at first estrus and randomly assigned across three replicates to one of three treatments: Control (C): daily injections of 1 ml saline d 0-64 of gestation; Early (E): daily injections of 5 mg rpST in 1 ml of injectable water d 0-30; or Late (L): 5 mg rpST d 30-64. Gilts were bled via jugular venipuncture at d 0 and every 15 d thereafter. Gilts were hysterectomized on d 65 of gestation and fetal and placental measurements taken. A fetus was considered nonviable if the fetus was partially resorbed. Fetal variables were analyzed using a model which included effects of treatment, replicate, sex, and sex x treatment interaction with replicate x treatment or sow(treatment, replicate) identified as error terms. The model for maternal variables included effects of treatment and replicate with treatment x replication as the error term. Enhanced fetal weight (P<.06) and length (P<.01) were observed in the L treatment group. There was no effect of treatment on ovulation rate, conceptus survival (# viable/# corpora lutea), or sow weight at d 65 of gestation. However, there was a replicate x treatment interaction (P<.03) due to poor survivability across all treatments in Replicate 2. There was a beneficial effect of L rpST treatment on fetal development in two of the three replicates. Early rpST treatment did not appear to result in this beneficial effect. Treatment with rpST increased (P<.0001) maternal plasma IGF-1 concentrations. These results suggest there may be an effect of L rpST treatment on fetal and placental growth under crowded uterine conditions.