Enhanced or reduced fetal growth induced by embryo transfer into smaller or larger breeds alters post-natal growth and metabolism in pre-weaning horses

Pauline Peugnet (1) , Laurence Wimel (2) , Guy Duchamp (3) , Charlotte Sandersen (4) , Sylvaine Camous (1) , Daniel Guillaume (5, 6) , Michèle Dahirel (1) , Cédric Dubois (2) , Luc Jouneau (1) , Fabrice Reigner (3) , Valérie Berthelot (7) , Stephane Chaffaux (1) , Anne Couturier-Tarrade (1) , Didier Serteyn (4) , Pascale Chavatte-Palmer (1)

1 BDR - Biologie du développement et reproduction
2 Station Expérimentale de la Valade
3 UE PAO - Unité Expérimentale de Physiologie Animale de l‘Orfrasiére
4 Faculté de Médecine Vétérinaire, Clinique Equine
5 PRC - Physiologie de la reproduction et des comportements [Nouzilly]
6 Institut Français du Cheval et de l'Equitation
7 MoSAR - Modélisation Systémique Appliquée aux Ruminants

In equids, placentation is diffuse and nutrient supply to the fetus is determined by uterine size. This correlates with maternal size and affects intra-uterine development and subsequent post-natal growth, as well as insulin sensitivity in the newborn. Long-term effects remain to be described. In this study, fetal growth was enhanced or restricted through ET using pony (P), saddlebred (S) and draft (D) horses. Control P-P (n = 21) and S-S (n = 28) pregnancies were obtained by AI. Enhanced and restricted pregnancies were obtained by transferring P or S embryos into D mares (P-D, n = 6 and S-D, n = 8) or S embryos into P mares (S-P, n = 6), respectively. Control and experimental foals were raised by their dams and recipient mothers, respectively. Weight gain, growth hormones and glucose homeostasis were investigated in the foals from birth to weaning. Fetal growth was enhanced in P-D and these foals remained consistently heavier, with reduced T3 concentrations until weaning compared to P-P. P-D had lower fasting glucose from days 30 to 200 and higher insulin secretion than P-P after IVGTT on day 3. Euglycemic clamps in the immediate post-weaning period revealed no difference in insulin sensitivity between P-D and P-P. Fetal growth was restricted in S-P and these foals remained consistently lighter until weaning compared to S-D, with elevated T3 concentrations in the newborn compared to S-S. S-P exhibited higher fasting glycemia than S-S and S-D from days 30 to 200. They had higher maximum increment in plasma glucose than S-D after IVGTT on day 3 and clamps on day 200 demonstrated higher insulin sensitivity compared to S-D. Neither the restricted nor the enhanced fetal environment affected IGF-1 concentrations. Thus, enhanced and restricted fetal and post-natal environments had combined effects that persisted until weaning. They induced different adaptive responses in post-natal glucose metabolism: an early insulin-resistance was induced in enhanced P-D, while S-P developed increased insulin sensitivity.

Mots clés: growth; dohad; foal; horse; embryo transfer

Domaines: Biologie de la reproduction; Biologie du développement

Pauline Peugnet, Laurence Wimel, Guy Duchamp, Charlotte Sandersen, Sylvaine Camous, et al.. Enhanced or reduced fetal growth induced by embryo transfer into smaller or larger breeds alters post-natal growth and metabolism in pre-weaning horses. PLoS ONE, 2014, 9 (7), pp.1-13. ⟨10.1371/journal.pone.0102044⟩. ⟨hal-01129848⟩