Effect of Porcine Somatotropin and Insulin on Prenatal Survival and Uteroplacental and Umbilical Cord Development in Gestating Gilts

Pregnant Yorkshire gilts were utilized to investigate the efficacy of exogenous administration of pST and/or insulin in enhancing prenatal piglet survival, uteroplacental and umbilical cord growth and development. Gilts were randomly assigned in a $2{\times}2$ factorial arrangement to four treatment combinations consisting of either daily i.m. injections of 5 mg pST (P, n=23); 0.50 IU/kg of insulin (I, n=23); combination of pST and insulin (P+I, n=23); or 1 ml of saline as control (C, n=23) from gestation Day 30 to 70. All gilts were sacrificed on gestation d 113 to evaluate piglet survival and uteroplacental or umbilical cord development Uteri were longer (346.3 vs 325.7 cm; p<0.05), and heavier (3122.8 vs 2940.7 g; p<0.05) in insulin treated gilts. Only placental macroscopic surface area was enhanced by maternal insulin injections (p<0.05) Incidence of umbilical cord abnormalities were low (14.3%), and they were independent of maternal treatment, occurring more in short cords than in long ones (21 vs 12%; p<0.05). A 6% increase in cord length (53.2 vs 48.6 cm; p=<0.05) was observed in piglets from treated gilts compared with controls. Significant sex differences (in favour of males) were observed in piglet weight, crown rump length and for most umbilical or placental parameters. Gilt weight gains from breeding to Day 113 of gestation were 10% and 15% greater in pST and insulin treated gilts compared with controls. These data indicate that prepartum injections of pST and/or insulin to gestating gilts seem to have a beneficial effect on uteroplacental or umbilical cord development and promote conditions conducive for perinatal piglet survival.