Effect of recombinant porcine somatotropin on fetal and placental growth in gilts with reduced uterine capacity.
Crowded uterine conditions were induced by unilateral hysterectomy-ovariectomy (UHO) in 42 gilts to determine the effect of recombinant porcine somatotropin on fetal and placental growth. Gilts were randomly assigned across three replicates to one of three treatments: Control (C; n = 14), daily injections of 1 mL saline from d 0 to 64 of gestation, Early (E; n = 12), 5 mg of rpST/d from d 0 to 30, followed by 1 mL saline from d 31 to 64, and Late (L; n = 16), 1 mL saline/d from d 0 to 29, followed by 5 mg of rpST/d from d 30 to 64 of gestation. Blood was collected from each gilt via jugular venipuncture at d 0 and every 15 d thereafter. Gilts were hysterectomized on d 65 of gestation. Length of placental attachment and fetal crown-rump length were measured. Placentas and fetuses were weighed. Placental length, wet weight, and dry weight were recorded. Treatment with rpST (either E or L) increased (P < 0.0001) maternal plasma IGF-I concentrations relative to controls. Treatment with rpST did not affect placental wet weight or placental DNA content. However, E and L treatments increased the percentage of placental protein (P = 0.01) and placental dry matter (P = 0.10) and increased contact area of uterine-placental interface (P = 0.01). Despite changes in placental composition and morphology, weights of fetuses collected from L-treated gilts did not differ from controls, whereas weights of fetuses collected from E-treated gilts tended to be less than controls (P < 0.06). Administration of rpST increased maternal IGF-I concentrations and placental surface area but failed to increase fetal growth in the UHO model. Therefore, mechanisms that are independent of maternal IGF-I or placental contact area may control early fetal growth under crowded uterine conditions.
Sterle
J A
JA
Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
Cantley
T C
TC
Matteri
R L
RL
Carroll
J A
JA
Lucy
M C
MC
Lamberson
W R
WR
D000818:Animals; D004247:DNA / Q000032:analysis; D005314:Embryonic and Fetal Development / Q000187:drug effects* / Q000502:physiology; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D007044:Hysterectomy / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D009929:Organ Size; D010920:Placenta / Q000033:anatomy & histology / Q000187:drug effects*; D010929:Placentation; D011247:Pregnancy; D011897:Random Allocation; D011994:Recombinant Proteins / Q000494:pharmacology; D013552:Swine / Q000196:embryology / Q000502:physiology*; D013997:Time Factors
D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D004247:DNA