Blondin P.,LAlliance Boviteq
Animal Reproduction | Year: 2014
The current world population is increasing at a fast rate. In order to feed this larger population, food production must increase by 70 percent. Recent reports show a record global production of 58.9 Carcass Equivalent Weight million metric tonnes of beef expected for 2014. It becomes clear that the worldwide agricultural community will have to integrate new technologies to assure the sustainability of global livestock and meat demands. Agriculture has benefited tremendously from the innovation of reproductive technologies such as semen artificial insemination and cryopreservation, embryo transfer and cryopreservation, and in vitro fertilization. Only recently have some developed countries accepted the import and export of frozen IVF embryos and more countries are currently evaluating this. Before 2003, in vitro embryos represented not more than 20% of all embryos produced. After 2003, this jumped to 30 to 39% of all embryos produced, and is increasing. It is clear that South America, and more specifically Brazil, is driving this increase. However, most people in this field would agree that the trend is true for many regions active in this field. International movement of gametes or embryos must be performed in biosecure manners to make certain that pathogenic organisms are controlled and that transmission of infection to recipient animals and progeny is avoided. The embryo transfer industry has adopted appropriate procedures to manage the biosecurity risks and hence mitigate risks of pathogen transmission through international trade of bovine embryos. Techniques for biosecure production of in vivo bovine embryos have been well established. However, as in vitro embryos are relatively new to this business, there are not many papers on the subject of pathogen-interaction with this type of embryo. Certain studies demonstrate that the decontamination of in vitro embryos using recommended procedures is effective for specific pathogens while others have shown that this is not as evident in other conditions. All agree that more research is needed regarding washing protocols for in vitro embryos. It is imperative that the scientific community continues its research to validate current embryo sanitary washing procedures and recommend any modifications that would be necessary for IVF embryos. As embryos are becoming an important component of international trade of bovine genetics, such research must not only continue but augment if key parties want to assure they meet the worldwide rising need of meat and dairy products.
Gilbert I.,Laval University |
Robert C.,Laval University |
Dieleman S.,University Utrecht |
Blondin P.,LAlliance Boviteq |
Sirard M.-A.,Laval University
Reproduction | Year: 2011
The LH surge induces a multitude of events that are essential for ovulation and corpus luteum formation. The transcriptional responses to the LH surge of preovulatory granulosa cells (GCs) are complex and still poorly understood. In this study, a genome-wide bovine oligo array was used to determine how the gene expression profile of GCs is modulated by the LH surge. GCs from three different stages were used to assess the short- and long-term effects of this hormone on follicle differentiation: 1) 2 h before induction of the LH surge, 2) 6 h and 3) 22 h after the LH surge. The results obtained were a list of differentially expressed transcripts for each GC group. To provide a comprehensive understanding of the processes at play, biological annotations were used to reveal the different functions of transcripts, confirming that the LH surge acts in a temporal manner. The pre-LH group is involved in typical tasks such as cell division, development, and proliferation, while the early response to the LH surge included features such as response to stimulus, vascularization, and lipid synthesis, which are indicative of cells preparing for ovulation. The late response of GCs revealed terms associated with protein localization and intracellular transport, corresponding to the future secretion task that will be required for the transformation of GCs into corpus luteum. Overall, results described in this study provide new insights into the different transcriptional steps that GCs go through during ovulation and before luteinization. © 2011 Society for Reproduction and Fertility.
Colleau J.J.,French National Institute for Agricultural Research |
Sargolzaei M.,LAlliance Boviteq |
Sargolzaei M.,University of Guelph
Journal of Animal Breeding and Genetics | Year: 2011
In real data, inbreeding is usually underestimated because of missing pedigree information. A method adapted to the dairy cattle situation is presented to approximate inbreeding when the stored population pedigree is incomplete. Missing parents in incomplete pedigrees were given a dummy identification and assigned to groups (up to nine for a given birth date of progeny). These groups were linked to contemporary reference groups with known parents. An explicit model considered that polygenic breeding values in a censored group were centred on a function of the average breeding value in the corresponding reference group and deviated independently. Inbreeding coefficients were obtained progressively over birth dates starting from founders. For each date considered, the parameters pertaining to its groups were computed using the parameters already obtained from groups belonging to the previous dates. The updating algorithms were given in detail. An indirect method was implemented to expedite mass computations of the relationship coefficients involved (MIM). MIM was compared to Van Raden's (VR) method using simulated populations with 20 overlapping generations and different rates of missing sires and dams. In the situation of random matings, the average inbreeding coefficients by date obtained by MIM were close to true values, whereas they were strongly underestimated by VR. In the situation of assortative matings, MIM gave average inbreeding coefficients moderately underestimated, whereas those of VR's method were still strongly underestimated. The main conclusion of this study adapted to the situation of dairy cattle with incomplete pedigrees was that corrections for inbreeding and coancestry coefficients are more efficient with an explicit appropriate genetic model than without. © 2011 Blackwell Verlag GmbH.
Bohmanova J.,University of Guelph |
Sargolzaei M.,LAlliance Boviteq |
Schenkel F.S.,University of Guelph
BMC Genomics | Year: 2010
Background: Effectiveness of genomic selection and fine mapping is determined by the level of linkage disequilibrium (LD) across the genome. Knowledge of the range of genome-wide LD, defined as a non-random association of alleles at different loci, can provide an insight into the optimal density and location of single-nucleotide polymorphisms (SNPs) for genome-wide association studies and can be a keystone for interpretation of results from QTL mapping.Results: Linkage disequilibrium was measured by |D'| and r 2between 38,590 SNPs (spaced across 29 bovine autosomes and the X chromosome) using genotypes of 887 Holstein bulls. The average level of |D'| and r 2for markers 40-60 kb apart was 0.72 and 0.20, respectively in Holstein cattle. However, a high degree of heterogeneity of LD was observed across the genome. The sample size and minor allele frequency had an effect on |D'| estimates, however, r 2was not noticeably affected by these two factors. Syntenic LD was shown to be useful for verifying the physical location of SNPs. No differences in the extent of LD and decline of LD with distance were found between the intragenic and intergenic regions.Conclusions: A minimal sample size of 444 and 55 animals is required for an accurate estimation of LD by |D'| and r 2, respectively. The use of only maternally inherited haplotypes is recommended for analyses of LD in populations consisting of large paternal half-sib families. Large heterogeneity in the pattern and the extent of LD in Holstein cattle was observed on both autosomes and the X chromosome. The extent of LD was higher on the X chromosome compared to the autosomes. © 2010 Bohmanova et al; licensee BioMed Central Ltd.
Tscherner A.,University of Guelph |
Gilchrist G.,University of Guelph |
Smith N.,University of Guelph |
Blondin P.,LAlliance Boviteq |
And 2 more authors.
Reproductive Biology and Endocrinology | Year: 2014
Background: Oocyte fertilization and successful embryo implantation are key events marking the onset of pregnancy. In sexually reproducing organisms, embryogenesis begins with the fusion of two haploid gametes, each of which has undergone progressive stages of maturation. In the final stages of oocyte maturation, minimal transcriptional activity is present and regulation of gene expression occurs primarily at the post-transcriptional level. MicroRNAs (miRNA) are potent effectors of post-transcriptional gene silencing and recent evidence demonstrates that the miR-34 family of miRNA are involved in both spermatogenesis and early events of embryogenesis. Methods: The profile of miR-34 miRNAs has not been characterized in gametes or embryos of Bos taurus. We therefore used quantitative reverse transcription PCR (qRT-PCR) to examine this family of miRNAs: miR-34a, -34b and -34c as well as their precursors in bovine gametes and in vitro produced embryos. Oocytes were aspirated from antral follicles of bovine ovaries, and sperm cells were isolated from semen samples of 10 bulls with unknown fertility status. Immature and in vitro matured oocytes, as well as cleaved embryos, were collected in pools. Gametes, embryos and ovarian and testis tissues were purified for RNA. Results: All members of the miR-34 family are present in bovine spermatozoa, while only miR-34a and -34c are present in oocytes and cleaved (2-cell) embryos. Mir-34c demonstrates variation among different bulls and is consistently expressed throughout oocyte maturation and in the embryo. The primary transcript of the miR-34b/c bicistron is abundant in the testes and present in ovarian tissue but undetectable in oocytes and in mature spermatozoa. Conclusions: The combination of these findings suggest that miR-34 miRNAs may be required in developing bovine gametes of both sexes, as well as in embryos, and that primary miR-34b/c processing takes place before the completion of gametogenesis. Individual variation in sperm miR-34 family abundance may offer potential as a biomarker of male bovine fertility. © 2014 Tscherner et al.; licensee BioMed Central Ltd.