Environmental factors and interval from the introduction of rams to estrus in postpartum Saint Croix sheep

ISSN： 0049-4747

Source： Tropical Animal Health and Production, Vol.43, Iss.4, 2011-04, pp. : 887-891

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The objective of this study was to determine whether season and total rainfall during the breeding season, sheep parity, and/or litter size affect the interval from the introduction of rams to estrus (IRE) in hair Saint Croix sheep in northeastern Mexico. An analysis was made of 874 services performed during 9 years, introducing the rams into the sheep flock after an isolation period of 60 days during the postpartum period. Estrus was recorded twice daily during 35 days. Year and season influenced significantly on the interval between ram introduction and estrus length (P < 0.01). winter="" ire="" length="" (7.9 ± 0.1 days)="" was="" shorter="" than="" in="" the="" other="" three="" seasons="" (11.1 ± 0.2,="" 11.1 ± 0.1,="" and="" 16.2 ± 0.2 days="" in="" summer,="" autumn,="" and="" spring,="" respectively)="">P < 0.01). an="" interaction="" was="" observed="" between="" rainfall="" and="" season,="" then="" by="" rainfall="" between="" 0="" and="" 100 mm,="" ire="" was="" shorter="">P < 0.05) in="" winter="" (6.8 ± 0.3 days),="" and="" by="" rainfall="" between="" 100="" and="" 199 mm,="" ire="" was="" shorter="">P < 0.05) in="" autumn="" (10.2 ± 0.5 days);="" however,="" when="" rainfall="" was="" beyond="" 200 mm,="" ire="" length="" was="" shorter="">P < 0.01) in="" summer="" (4.8 ± 0.5 days)="" than="" in="" autumn="" (14.5 ± 0.3 days).="" the="" ire="" length="" was="" also="" longer="" in="" first="" lambing="" ewes="">P < 0.05) and="" was="" not="" affected="" by="" litter="" size.="" in="" the="" present="" study,="" several="" factors,="" including="" the="" breeding="" season,="" rainfall="" and="" parity,="" directly="" influenced="" the="" interval="" between="" the="" male="" introduction="" and="" the="" onset="" of="" estrus="" by="" saint="" croix="" hair="" sheep.="">