Novel Insights into the Bovine Polled Phenotype and Horn Ontogenesis in Bovidae

Despite massive research efforts, the molecular etiology of bovine polledness and the developmental pathways involved in horn ontogenesis are still poorly understood. In a recent article, we provided evidence for the existence of at least two different alleles at the Polled locus and identified candidate mutations for each of them. None of these mutations was located in known coding or regulatory regions, thus adding to the complexity of understanding the molecular basis of polledness. We confirm previous results here and exhaustively identify the causative mutation for the Celtic allele (PC) and four candidate mutations for the Friesian allele (PF). We describe a previously unreported eyelash-and-eyelid phenotype associated with regular polledness, and present unique histological and gene expression data on bovine horn bud differentiation in fetuses affected by three different horn defect syndromes, as well as in wild-type controls. We propose the ectopic expression of a lincRNA in PC/p horn buds as a probable cause of horn bud agenesis. In addition, we provide evidence for an involvement of OLIG2, FOXL2 and RXFP2 in horn bud differentiation, and draw a first link between bovine, ovine and caprine Polled loci. Our results represent a first and important step in understanding the genetic pathways and key process involved in horn bud differentiation in Bovidae

Repeated OPU on four Blonde d'Aquitaine cows: variation in the stimulation response and in the rate of diploid oocytes after in vitro maturation

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Superovulatory response and oocyte recovery after ovum pick up in feed restricted heifers with two profiles of AMH

Anti–Müllerian hormone (AMH) was found to be a reliable endocrine marker of the population of small antral gonadotropin-responsive follicles in the cow. The measurement of circulating AMH concentrations can help predicting the follicular and ovulatory responses to gonadotrophin treatment in cows (Rico et al., 2009, Rico et al., 2012). The aim of this study was to determine the superovulatory response and the number and quality of oocytes recovered by Ovum Pick Up (OPU) in feed restricted heifers (LWG: 600g/d) with two profiles of AMH. Sixteen Holstein heifers (15.8 ± 1.2 months old; LW: 370±41.2 kg) were grouped according to AMH concentrations: low (L = 1-80 pgmL-1; n=7) or high (H: >150 pgmL-1; n=9). Plasma concentrations of AMH were determined using AMH GENII ELISA kit (Beckman Coulter France, Roissy CDG, France), as described previously (Monniaux et al., 2008). OPU was performed during two periods (P1 and P2) at an interval of 6 weeks. Two OPUs were performed in each period. Before each OPU, estrous cycles were synchronized with subcutaneous 3mg Norgestomet implants (Crestar; MSD, Angers, France) inserted under the convex surface of the ear for 9 days. On the day of implant insertion, heifers received an i.m. injection of GnRH (Receptal®, Intervet, Angers, France). Two days before implant removal, 500 μg cloprostenol (Estrumate®; Schering-Plough, Levallois-Perret, France) were injected. On day 2.5 of the synchronized estrous cycle (day 0 was the day of estrus), heifers were superovulated with a total dose of 300 μg follicle-stimulating hormone (pFSH; Stimufol ; Reprobiol, Belgium) divided into 5 i.m. injections given 12 h apart, at decreasing doses. Cumulus–oocyte complexes were collected by OPU 12 h after the last FSH injection (day 5 of the cycle). Oocytes were graded for quality as, 1, 2, 3 and 4, according to Marquant-Le Guienne (1998). Before OPU all follicles (diameter 3-12 mm) were counted. The statistical analyses (Student’s T test and data correlation) were performed using GraphPadprism. There was a high correlation in both periods 1 and 2 between AMH concentrations and the number of follicles aspirated (P1: r=0.86, P<0.0001; P2: r=0.74, P<0.001), the number of oocytes collected (P1: r= 0.83, P< 0.0001; P2: r=0.81, P < 0.0001) and the number of quality 1, 2 and 3 oocytes (P1: r=0.84, P<0.0001; P2: r=0.82, P<0.0001). Animals with AMH H had significantly higher numbers of aspirated follicles, total oocytes and 1, 2 and 3 quality oocytes than AMH L animals (Table 1). The percentage of 1, 2 and 3 quality oocytes and the percentage of follicles aspirated were similar between AMH H and AMH L. There was no significantly difference between periods. The number of oocytes aspirated was not altered by multiple stimulations

Expression des Pregnancy associated glycoproteins par les cellules trophoblastiques et par les cellules du cumulus chez le bovin

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Phenotyping the reproduction function in cattle: inputs from functional genomics and epigenetics

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