title: Split-weaning before altrenogest synchronization of multiparous sows alters follicular development and reduces embryo survival.
abstract: This study used split-weaning (SW) to induce differences in follicle size at weaning and study its consequences for follicle development during and after post-weaning altrenogest feeding and for reproductive performance. Multiparous sows (n=47) were assigned to SW (n=23; litter size reduced to the six smallest piglets 3 days before weaning) or control (C; n=24; normal weaning). Altrenogest (20 mg/day) was fed to all 47 sows from Day -1 till Day 5 (complete weaning = Day 0). Follicle size on Day 1, 2 and 8 was smaller in C than in SW (p ≤ 0.05). Ovulation rate was similar, but C sows had higher embryo survival rate (ESR) than SW sows (83 ± 19 and 58 ± 31%, respectively; p=0.001). SW sows with low ESR (<63%; n=10) had a greater follicle size on days 3-6 than SW sows with high ESR (>63%; n=10; p ≤ 0.04). A decrease in follicle size between Day 5 and 6 of altrenogest feeding was associated with increased ESR in both treatments (p=0.002). Follicle pool analyses (assessment of all follicles >2 mm) revealed that on Day 3, sows with low ESR had a higher % of follicles >5 mm compared with sows with high ESR (30% vs 10%; p=0.04). Thus, sows in which follicle growth was less suppressed during altrenogest feeding had a lower ESR. These effects on follicle development and ESR were more pronounced in split-weaned sows.
authors: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, Wageningen, the Netherlands.
authors: J J J
authors: JJ
authors: van Leeuwen
authors: M
authors: M
authors: Verhoeven
authors: I
authors: I
authors: van der Heden-van Noort
authors: S
authors: S
authors: Kranenbarg
authors: B
authors: B
authors: Kemp
authors: N M
authors: NM
authors: Soede
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000502:physiology*; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D006080:Ovarian Follicle / Q000187:drug effects / Q000254:growth & development*; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary; D010298:Parity; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011372:Progestins / Q000008:administration & dosage; D012098:Reproduction / Q000502:physiology; D013552:Swine / Q000502:physiology*; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives*; D014886:Weaning
chemical_list: D011372:Progestins; C023445:altrenogest; D011374:Progesterone; D014204:Trenbolone Acetate