Supplementation during pregnancy on the production and metabolic profile of Polwarth sheep

The aim of this study was to evaluate the effect of supplementation during different stages of pregnancy on the development and productive performance of Polwarth sheep. Fifty-three adult ewes under synchronised pregnancy were submitted to a supplement of 1.5% body weight with commercial feed during the different stages of pregnancy on natural pasture: NS - no supplementation, SIG - supplemented during the initial third of pregnancy, SMG - supplemented during the middle third of pregnancy, SFG - supplemented during the final third of pregnancy, and STG - supplemented throughout pregnancy. The ewes were weighed at the time of laparoscopic insemination, at every third stage of the pregnancy, and two days before the expected lambing date, at which time the body condition score and metabolic markers were evaluated. The pre-lambing weight of the STG ewes was greater than that of the SFG and SMG ewes, which were, in turn, greater than the SIG and NS ewes. Body condition was superior in the STG and SFG ewes. Lamb survival was greater in the STG and SFG ewes, and lower in the SMG, SIG and NS ewes. Beta-hydroxybutyrate was lower in the SFG and STG ewes. Supplementation during the final third and throughout pregnancy increases the rates of survival and production in the lambs, with supplementation only during the final third of gestation being less costly for the production system.