<abstract xmlns="http://www.w3.org/1999/xhtml"><p> An appropriate management of reproduction allows ewes to breed at a more intensive rhythm, more compatible with economic efficiency of farms. Hence, the objectives of the present work were to evaluate a traditional estrus synchronization protocol (based on medroxyprogesterone acetate-impregnated intravaginal sponges combined or not with equine chorionic gonadotropin) on a Merino sheep herd during the breeding season, in order to determine the best working protocol for this breed. A total of 277 sheep, blocked by age (200 ewes and 77 ewe lambs) were randomly allocated to four groups, two of ewes (E and Ee) and two of ewe lambs (L and Le). All females received 60 mg MAP (medroxyprogesterone acetate) sponges on the first day. At the day of removal the animals of groups Ee and Le received 450 IU of eCG (equine chorionic gonadotropin). Mean estrus synchronization rate was 92.06% and similar among groups. Time to estrus was shorter for Ee (46.93±12.44 h) and Le (44.34±10.76 h), when compared to treatments without eCG (60.60±20.46 h and 58.68±17.72 h for E and L, respectively; P&lt;0.05 for both). Pregnancy rates were 71.35 and 72.86% for ewes and ewe lambs, respectively, and similar among groups. Lambing rates were lower in ewes (1.36) than in ewe lambs (1.85) with no significant effect of eCG. The study demonstrates the efficacy of the synchronization method with MAP and the reduction in the time to estrus induced by eCG in Spanish Merino ewes and ewe lambs during the breeding season.</p></abstract>

An appropriate management of reproduction allows ewes to breed at a more intensive rhythm, more compatible with economic efficiency of farms. Hence, the objectives of the present work were to evaluate a traditional estrus synchronization protocol (based on medroxyprogesterone acetate-impregnated intravaginal sponges combined or not with equine chorionic gonadotropin) on a Merino sheep herd during the breeding season, in order to determine the best working protocol for this breed. A total of 277 sheep, blocked by age (200 ewes and 77 ewe lambs) were randomly allocated to four groups, two of ewes (E and Ee) and two of ewe lambs (L and Le). All females received 60 mg MAP (medroxyprogesterone acetate) sponges on the first day. At the day of removal the animals of groups Ee and Le received 450 IU of eCG (equine chorionic gonadotropin). Mean estrus synchronization rate was 92.06% and similar among groups. Time to estrus was shorter for Ee (46.93±12.44 h) and Le (44.34±10.76 h), when compared to treatments without eCG (60.60±20.46 h and 58.68±17.72 h for E and L, respectively; P<0.05 for both). Pregnancy rates were 71.35 and 72.86% for ewes and ewe lambs, respectively, and similar among groups. Lambing rates were lower in ewes (1.36) than in ewe lambs (1.85) with no significant effect of eCG. The study demonstrates the efficacy of the synchronization method with MAP and the reduction in the time to estrus induced by eCG in Spanish Merino ewes and ewe lambs during the breeding season.

Synchronization Protocols in Spanish Merino Sheep: Reduction in Time to Estrus by the Addition of eCG to a Progesterone-Based Estrus Synchronization Protocol

Department of Applied Science and Technology, Catholic University of Valencia “San Vicente Mártir” 46001 Valencia, Spain

Department of Cell Biology, Immunology and Physiology, Cordoba University, 14071 Córdoba, Spain

Department of Animal Reproduction, INIA, 28040 Madrid, Spain

Department of Physiology, Murcia University, 30100 Murcia, Spain

Annals of Animal Science

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

An appropriate management of reproduction allows ewes to breed at a more intensive rhythm, more compatible with economic efficiency of farms. Hence, the...

Synchronization Protocols in Spanish Merino Sheep: Reduction in Time to Estrus by the Addition of eCG to a Progesterone-Based Estrus Synchronization Protocol

Published Online: Apr 23, 2015

Page range: 409 - 418

Received: Aug 13, 2014

Accepted: Dec 01, 2014

DOI: https://doi.org/10.1515/aoas-2015-0003

Keywords
Spanish Merino sheep, age, estrus synchronization, reproductive response, eCG

© by Salvador Ruiz

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Synchronization Protocols in Spanish Merino Sheep: Reduction in Time to Estrus by the Addition of eCG to a Progesterone-Based Estrus Synchronization Protocol

Published Online: Apr 23, 2015

Page range: 409 - 418

Received: Aug 13, 2014

Accepted: Dec 01, 2014

DOI: https://doi.org/10.1515/aoas-2015-0003

KeywordsSpanish Merino sheep, age, estrus synchronization, reproductive response, eCG

© by Salvador Ruiz

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Spanish Merino sheep, age, estrus synchronization, reproductive response, eCG