The reuse of Norgestomet implants on estrus manifestation ov

Abstract

This study assessed the efficacy of the re-utilization of a Norgestomet ear implant in the sheep. Following body condition scoring (CC 3-4) and weight (50-60 Kg) evaluation 60 Texel ewe lambs were randomly assigned to two experimental groups: NorgN (new) control group (n=30), and NorgR (re-used) treatment group (n=30). The implants employed in the treatment group were previously used in estrus synchronization of cows. The ewe lambs were treated with 1/3 of the dosage of Norgestomet recommended for cows. The estrus synchronization protocol consisted of administration of an ear implant at day 0 (beginning of experiment) for 6 days. At implant removal (day 6) the animals received i.m. injections of a prostaglandin analogue (xxx mg) and eCG (400 IU). Teaser rams with brisket paint were used to mark the ewes in heat for 5 days after implant withdrawal. In total, 95% (57/60) of the ewes displayed estrus. 100% (30/30) and 90% (27/30) of the ewes in NorgN and NorgR groups, respectively, displayed estrus 36 hours after implant removal. In conclusion, Norgestomet ear implants associated with eCG and a prostaglandin analogue can be successfully reused to synchronize estrus in Texel ewe lambs.