Editing Horse (section)

==Reproduction and development==
{{Main|Horse breeding}}

[[File:Mare foal poland.jpg|thumb|Mare with a foal]]
[[Gestation]] lasts approximately 340&nbsp;days, with an average range 320–370 days,<ref name=Ensminger156>[[#Ensminger|Ensminger]], p. 156</ref><ref>{{Cite web |title=How Long is a Horse Pregnant? |url=https://talkoftheturf.com/article/how-long-is-a-horse-pregnant |access-date=2023-03-25 |website=Talk of the Turf |language=en}}</ref> and usually results in one [[foal]]; twins are rare.<ref>{{cite web|url= http://www2.okstate.edu/pio/twinfoals.html|access-date= 2008-09-23|title= Rare Twin Foals Born at Vet Hospital: Twin Birth Occurrences Number One in Ten Thousand|author= Johnson, Tom|website= Communications Services, Oklahoma State University|publisher= Oklahoma State University|archive-url= https://web.archive.org/web/20121012052136/http://www2.okstate.edu/pio/twinfoals.html|archive-date= 2012-10-12|url-status= dead}}</ref> Horses are a precocial species, and foals are capable of standing and running within a short time following birth.<ref>{{cite book |author1=Miller, Robert M. |author2=Rick Lamb|title=Revolution in Horsemanship and What it Means to Mankind |publisher= Lyons Press|location=Guilford, CT|year=2005|isbn=1-59228-387-X |oclc=57005594|pages=102–103}}</ref> Foals are usually born in the spring. The [[estrous cycle]] of a mare occurs roughly every 19–22 days and occurs from early spring into autumn. Most mares enter an ''anestrus'' period during the winter and thus do not cycle in this period.<ref name=Ensminger150>[[#Ensminger|Ensminger]], p. 150</ref> Foals are generally [[weaning|weaned]] from their mothers between four and six months of age.<ref>{{cite web|url=http://www.extension.org/pages/29352/reducing-weaning-stress-in-foals|author=Kline, Kevin H.|title=Reducing weaning stress in foals |publisher=Montana State University eXtension|date=2010-10-07|access-date=2012-04-03|url-status=dead|archive-url=https://web.archive.org/web/20120322182958/http://www.extension.org/pages/29352/reducing-weaning-stress-in-foals|archive-date=2012-03-22}}</ref>

Horses, particularly colts, are sometimes physically capable of reproduction at about 18&nbsp;months, but domesticated horses are rarely allowed to breed before the age of three, especially females.{{r|EnsmingerHT|page=129}} Horses four years old are considered mature, although the skeleton normally continues to develop until the age of six; maturation also depends on the horse's size, breed, sex, and quality of care. Larger horses have larger bones; therefore, not only do the bones take longer to form [[Bone|bone tissue]], but the [[epiphyseal plate]]s are larger and take longer to convert from [[cartilage]] to bone. These plates convert after the other parts of the bones, and are crucial to development.<ref>{{cite web|url=http://www.equineortho.colostate.edu/questions/dod.htm|title=Developmental Orthopaedic Disease: Problems of Limbs in young Horses|access-date=2008-04-20|author=McIlwraith, C.W.|publisher=Colorado State University|website=Orthopaedic Research Center|archive-date=2013-01-14|archive-url=https://web.archive.org/web/20130114221212/http://csu-cvmbs.colostate.edu/academics/clinsci/equine-orthopaedic-research-center/Pages/default.aspx|url-status=live}}</ref>

Depending on maturity, breed, and work expected, horses are usually put under saddle and [[horse training|trained]] to be ridden between the ages of two and four.<ref name=Train163>{{cite book|author=Thomas, Heather Smith |title=Storey's Guide to Training Horses: Ground Work, Driving, Riding |publisher=Storey Publishing |location=North Adams, MA |year=2003 |isbn=1-58017-467-1 |page=[https://archive.org/details/storeysguidetotr0000thom/page/163 163] |url=https://archive.org/details/storeysguidetotr0000thom/page/163}}</ref> Although [[Thoroughbred]] [[Horse racing|race horses]] are put on the track as young as the age of two in some countries,<ref>{{cite web|url= http://www.jockeyclub.com/factbook.asp?section=11|title= 2-Year-Old Racing (US and Canada)|access-date= 2008-04-28|website= Online Fact Book|publisher= Jockey Club|archive-date= 2013-02-16|archive-url= https://web.archive.org/web/20130216002618/http://www.jockeyclub.com/factbook.asp?section=11|url-status= live}}</ref> horses specifically bred for sports such as [[dressage]] are generally not put under saddle until they are three or four years old, because their bones and muscles are not solidly developed.<ref>{{cite book |title=The USDF Guide to Dressage |url=https://books.google.com/books?id=9NNobNYAiroC&pg=PA272 |author1=Bryant, Jennifer Olson |author2=George Williams |publisher=Storey Publishing |year=2006 |isbn=978-1-58017-529-6 |pages=271–272 |access-date=2020-09-28 |archive-date=2023-03-20 |archive-url=https://web.archive.org/web/20230320223812/https://books.google.com/books?id=9NNobNYAiroC&pg=PA272 |url-status=live }}</ref> For [[endurance riding]] competition, horses are not deemed mature enough to compete until they are a full 60&nbsp;calendar months (five years) old.<ref name=Endurance/>