Maternal parity affects placental development, growth and metabolism of foals until 1 year and a half M. Robles a , C. Dubois b , C. Gautier c , M. Dahirel a , I. Guenon c , H. Bouraima-Lelong c , C. Vigui  e d , L. Wimel b , A. Couturier-Tarrade a , P. Chavatte-Palmer a, * a UMR BDR, INRA, ENVA, Universit e Paris Saclay, 78350, Jouy en Josas, France b IFCE, Station Exp erimentale, Chamberet, France c Normandie Univ, UNICAEN, EA2608, OeReCa, USC-INRA, Caen, France d INRA, UMR Toxalim, Research Center in Food Toxicology, Toulouse, France article info Article history: Received 28 August 2017 Received in revised form 1 December 2017 Accepted 7 December 2017 Available online 21 December 2017 Keywords: Horse Parity DOHaD Metabolism Placenta abstract Primiparous mares are known to produce smaller foals than multiparous mares. This difference seems to be partly explained by the reduced exchange surface and volume of the placental villi in primiparous compared to multiparous placentas. The effect of maternal parity on foals' post-natal growth, meta- bolism and sexual maturation, however, has been given little consideration. The objectives of this work were to analyse placental biometry and structure at term, growth of foals and yearlings, their metabolism and testicular maturation at one year of age. Twenty multiparous mares (M), aged over 6 years and 12 primiparous mares (P), aged up to 5 years were artificially inseminated with the same stallion and monitored the same way until foaling. At birth, foals and placentas were measured and placentas were sampled above at the umbilical cord insertion, as well as in the pregnant and the non-pregnant horn to perform stereological analyses. Foals were weighed and measured until 540 days of age. At 120 and 360 days of age, an Intravenous Glucose Tolerance Test was performed on foals and yearlings. At 360 days of age, the males were castrated and testicular maturation analysed by RT-qPCR. At birth, P dams produced lighter and smaller foals and placentas. The foal birth weight to placental surface ratio was lower in the P compared to the M group. P Foals remained lighter than M foals until 360 days of age and smaller until at least 540 days of age. At 120 days of age, P foals had a higher glucose tolerance than M foals, and then may be less mature than M foals in terms of the control of their glucose homeostasis. At 360 days of age, the testicles of prepubertal P stallions were less mature in the P vs the M group. In conclusion, primiparous dams produce intrauterine growth restricted, less mature and smaller foals compared to multiparous dams with altered metabolism and growth until at least 540 days of age. These differences could affect the sport career of these foals, especially if it begins at an early age. © 2017 Published by Elsevier Inc. 1. Introduction Studies in human populations and experimental works in non- equine animals have demonstrated that the maternal environ- ment affects feto-placental development and can increase the risk of developing non-communicable diseases at adulthood [1e4]. This concept is referred to as the Developmental Origins of Health and Disease (DOHaD). In the horse, intra uterine growth restriction (IUGR), experimentally induced by embryo transfers of Saddlebred horses into pony mares, was shown to impair feto-placental development and postnatal growth of the offspring until 3 years of age, to alter glucose metabolism until weaning and to increase the risk of developing osteochondrosis at 6 months of age [5e7]. Incidentally, primiparous mares are known to produce lighter and smaller foals at birth compared to multiparous mares [8e16]. These foals remain smaller until one year of age [9, 12, 14, 16]. They have lighter, smaller and less voluminous placentas [10, 11 , 16] with a reduced microscopic area of fetomaternal contact compared to * Corresponding author. E-mail address: pascale.chavatte-palmer@inra.fr (P. Chavatte-Palmer). Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com https://doi.org/10.1016/j.theriogenology.2017.12.019 0093-691X/© 2017 Published by Elsevier Inc. Theriogenology 108 (2018) 321e330