Age of the Jeju pony Emphasis Type="Italic"Equu

Authors: Jeong R Rho Robert B Srygley Jae C Choe

Publish Date: 2009/01/17

Volume: 27, Issue: 3, Pages: 483-488

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Abstract

In a related paper we showed that mares that reproduced early in life tended to have higher fecundity because of a decrease in the duration of interbirth intervals relative to mares that reproduced later in life However we know that young mares are subordinate to older mares Hence costs associated with low dominance rank might offset the benefits of earlier reproduction We compared harassment of foals of female Jeju ponies that first reproduced at three years of age with that of foals of females that first reproduced at five years of age As a consequence of their positions in the linear dominance hierarchy foals born to and guarded by young mares were harassed more frequently than foals whose mothers were older when they first reproduced A mare that reproduced early in life guarded her offspring more closely and intervened between her foal and neighboring mares more frequently than those mares which first reproduced when older This need to guard their foals and the harm that might ensue from frequent harassment might counterbalance selection towards earlier reproduction in maresWe are grateful to Katherine A Houpt Susan Lappan and Daniel Mills for comments on the manuscript We thank the Korean Institute for Livestock Promotion for data on reproduction of the mares on the farm since 1986 and Hong S Kim Chang S Park and other farm keepers for the care of horses on the farm We are also very grateful to Hang K Oh and Jung Y Song for providing assistance at the start of this study This study was supported by a BK21 Research Grant from the Korean Ministry of Education and Human Research Development

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