"Grootlamsiekte", a specific syndrome of prolonged gestation in sheep : further investigations

Abstract

By feeding both leaves and twigs of Salsola tuberculata var. tomentosa to pregnant ewes, it was established that the daily ingestion of 0,9 kg of this material for at least 10 to 50 days during any stage of gestation could result in postmaturity. The leaves mainly affected the terminal 50 days of pregnancy, whereas the twigs prolonged gestation even when fed during the initial 50 days. The longest gestation period after feeding twigs was 205 days and after leaves 214 days. Many of the lambs born between 150 and 165 days of gestation were either smaller than or equal in size to control lambs and enlarged ones were born mainly after longer periods. The heaviest experimental post-mature lamb mass-measured 9,46 kg. Normal post-natal development of multiple vesicular follicles was found in the ovaries of lambs born at normal term. This may at least partly explain the presence of ovarian polyfollicularity in post-maturity. Partus was frequently successfully induced by using stilboestrol and oxytocin, especially between 150 and 170 days of gestation. Many dystocias, however, occurred. The shrub is apparently most harmful when the dormant stages are ingested, especially during droughts. This phenomenon may be related either to an increased intake or to increased toxicity or to both factors.