FETAL MORTALITY IN THE PREPUBERAL GILT

Abstract

Forty prepuberal gilts weighing from 45 to 55 kg were injected with 1000 IU of pregnant mare’s serum (PMS), followed 48 hours later by an injection of 500 IU of human chorionic gonadotrophin (HCG) and 10 mg of diethylstilbestrol (DES). They were inseminated 24 hours after the HCG and DES injections. Ten gilts killed four days after insemination ovulated a mean of 18 ova; 91% of the ova recovered were fertilized, of which 81% were in the morula stage and undergoing normal cleavage. A mean daily oral intake of 26.4 mg of chlormadinone acetate (CAP) and 52.8 μg of DES per gilt, commencing seven days after insemination, appeared to assist in the maintenance of pregnancy early in gestation, as seven of nine gilts killed at 20 days of gestation were pregnant (anatomical abnormalities were found in the other two gilts) whereas a similar intake of hormones failed to maintain pregnancy in 15 gilts slaughtered 50 days after insemination. Similarly, six gilts administered 1000 IU of PMS and 500 IU of HCG at 9 and 11 days of gestation, respectively, in an attempt to induce a second set of corpora lutea, were not pregnant when killed 50 days after insemination. All 21 gilts slaughtered 50 days after insemination displayed complete regression of the corpora lutea. Maintenance of pregnancy to 20 days of gestation by oral administration of CAP and DES suggests that fetal mortality subsequent to this period was due to a lack of endogenous hormonal support.