111 FUNCTIONAL AND MOLECULAR GENITAL ASYMMETRY IN THE COW

Abstract

Bilateral asymmetry in the cow affects ovarian function, uterine horn morphology, pregnancy, and embryonic sex. However, many aspects and molecular mechanisms of such laterality remain obscure. The objective of this work was identifying new traits of ovarian and uterine asymmetry, as based on oestrus and ovarian monitoring, P4 concentrations, early embryo development, flushing performance, and pregnancy outcomes after embryo transfer (ET). In addition, proteins identified in previous work by difference gel electrophoresis and mass spectrometry (DIGE-MS) in uterine fluid (UF) were reanalyzed in a horn-of-origin basis (n = 16 and n = 14 flushes from left and right horns, respectively; Muñoz et al. 2012 J. Proteome Res. 11, 751–766; Gómez et al. 2011 Reprod. Fert. Dev. 24, 152). Studies were performed in experimental herd and on field. Data were analyzed by Proc GLM of SAS/STAT (Version 9.2; SAS Inst. Inc., Cary, NC) and REGWQ test for means. In experimental herd, we analyzed ovarian and uterine asymmetry within animals (n = 25) monitored through different reproductive cycles (n = 109). Animals synchronised with progestagen + PGF2α were alternatively transferred with IVP embryos (n = 30–60) or vehicle (sham transfer) on Day 5 to ipsilateral horn. On Day 8, embryos and/or diluted UF were recovered by flushing with 30 or 45 mL PBS. Nonsignificant differences (P > 0.7) were obtained in ovulatory follicle diameters 48 h after PGF_2α injection, onset oestrus time and recoverable total protein by flushing between animals ovulating in the left or in the right ovary. However, cows bearing the corpus luteum (CL) in the right ovary (i.e. right) had higher (26.3 ± 1.5) Day 8 P4 concentration than those showing a CL in the left ovary (i.e. left) (21.6 ± 1.8) (P = 0.03). Fluid recovery (%) was lower in the left (47.0 ± 6.3) than in the right (64.4 ± 5.0) horn when 30 mL were infused (P = 0.035); in contrast, 45 mL infused did not differ between horns (61.6 ± 4.1 v. 67.9 ± 4.1). Less total embryos were recovered from the left (14.6 ± 4.7) than the right (31.0 ± 3.7) horn (P < 0.02), although the relative proportions of viable embryos were conserved. Among 76 proteins analyzed, concentrations of VLCAD, KPYM, CFB, ALB, FGG, EZR, and ACTB were higher (P ≤ 0.05), while TWF1 and ENO1 were lower in the left horn. On field experiments (n = 184 ET in 286 synchronised animals from 39 farms; ≥3 ET per farm) confirmed on Day 7 the above differences in P4 (right: 8.3 ± 0.43 v. left: 6.1 ± 0.55; P = 0.0058). Pregnancy rates after ET did not differ between horns (51.0 ± 3.6, right v. 53.2 ± 4.7, left). However, P4 concentrations differ (P = 0.018) between pregnant and open animals in the left (15.9 ± 1.7 v. 8.3 ± 1.2) but not in the right horn (12.4 ± 1.3 v. 12.4 ± 1.2), respectively. Genital asymmetry in the cow has physical concerns (flushing and recoveries), while changes in P4 and/or proteins could operate to hold similar pregnancy rates between horns.

Project AGL2009-10059 (MICINN). MM, BT and EC are sponsored by RYC08-03454, Cajastur and FPU2009-5265, respectively.