@article{MAKHILLJAVA20131264085,
    title = {Different Effects of Month of Conception and Birth on Gestation Length in 
  Mares},
    journal = {Journal of Animal and Veterinary Advances},
    volume = {12},
    number = {6},
    pages = {731-735},
    year = {2013},
    issn = {1680-5593},
    doi = {javaa.2013.731.735},
    url = {https://makhillpublications.co/view-article.php?issn=1680-5593&doi=javaa.2013.731.735},
    author = {Petr,Zdenek,Petr and},
    keywords = {foal sex,parturition,Gestation length,horse,conception},
    abstract = {Equine prenatal development is subjected to a great variety 
  of effects. The aim of the study was to compare the effects of the month of 
  conception and month of birth on gestation length in mares. Data from 321 pregnancies 
  were used. The conception occurred between February and August. Mares that conceived 
  early in the year had a longer gestation than mares that conceived later in 
  the breeding season (p<0.001). Foals were born between January and July. 
  The gestation period increased in mares that foaled from January to April (p<0.001) 
  and then decreased in later months. Mares carrying male fetuses had a longer 
  gestation (p<0.05) than those carrying female fetuses. Mare age, stud farm 
  and year of foal birth had no significant influence on gestation length. In 
  conclusion, the data suggest that the effects of the month of conception and 
  month of foaling on gestation length are the reverse in the first third of the 
  year.}
    }