Effects of metabolic changes produced in ewes with subclinical pregnancy toxemia over reproductive parameters

The objective of this work was to determine the repercussion of the metabolic changes that occur in induced subclinical pregnancy toxemia in single- or twin-bearing ewes on the duration of gestation, type and length of lambing, and placental expulsion time. Fifty-one adult Corriedale ewes with a known gestation date and fed in the wild were randomly divided at day 145 of gestation into four groups. Group A included single-bearing ewes, and C twin-bearing ewes, all of which were fed ad libitum . Group B was composed of single-bearing ewes, and D of twin-bearing ewes, all subjected to a 75% feed restriction until glycemic values were compatible with subclinical pregnancy toxemia. Metabolic parameters were determined in all ewes from day 145 of gestation to 72 h postpartum. Likewise, the duration of gestation, type of lambing (eutocic/dystocic), labor length, and placental expulsion time were recorded. Glycemia and β-hydroxybutyrate values compatible with subclinical pregnancy toxemia were achieved after 48 h of feed restriction, being 30.67±2.37 mg/dL and 1.87±0.12 mmol/L in single-bearing ewes and 28.40±3.39 mg/dL and 2.21±0.42 mmol/L in twin-bearing ewes, respectively. It is concluded that subclinical pregnancy toxemia induced by feed restriction at the end of gestation, frequent situation that occurs in flock management, produces mild metabolic changes, which return to normal values after the delivery. These metabolic changes registered before lambing do not modify the gestation length, do not increase the percentage of dystocical deliveries, nor influence labor length or placental expulsion time.