Genetic merit for fertility traits in Holstein cows: VI. Oocyte developmental competence and embryo development
| Autor: | Stephen T. Butler, S.G. Moore, Patrick Lonergan, Solomon Mamo, S. B. Cummins, Trudee Fair |
|---|---|
| Přispěvatelé: | National Development Plan, Dairy Levy Ireland |
| Rok vydání: | 2019 |
| Předmět: |
Candidate gene
Animal breeding Genotype medicine.medical_treatment ovum pick-up Embryonic Development Oocyte Retrieval Superovulation Biology Andrology 03 medical and health sciences Pregnancy Genetics medicine Animals Lactation Blastocyst Insemination Artificial 030304 developmental biology 0303 health sciences Reproduction Artificial insemination Uterus Embryogenesis 0402 animal and dairy science Embryo 04 agricultural and veterinary sciences Embryo Transfer Oocyte medicine.disease 040201 dairy & animal science Fertility Milk Phenotype medicine.anatomical_structure embryonic structures gene expression Oocytes Cattle Female Animal Science and Zoology Food Science |
| Zdroj: | Journal of Dairy Science. 102:4651-4661 |
| ISSN: | 0022-0302 |
| DOI: | 10.3168/jds.2018-15813 |
| Popis: | peer-reviewed The hypothesis of this study was that cows with good genetic merit for fertility traits (Fert+) would produce oocytes and embryos of greater quality than cows with poor genetic merit for fertility traits (Fert−) and that mRNA expression of candidate genes would reflect the observed differences in quality. The aim of the study, therefore, was to determine the effect of genetic merit for fertility traits on morphological classification and mRNA abundance of key genes in immature oocytes and cumulus cells following ovum pick-up and in embryos following superovulation, artificial insemination (AI), and uterine flushing. In experiment 1, 17 Fert+ and 11 Fert− cows, ranging from 54 to 84 d in milk, were submitted to ovum pick-up on 4 occasions during a 2-wk period. Recovered cumulus–oocyte complexes (COC) were morphologically graded. Oocytes and cumulus cells were separated, and mRNA abundance of genes associated with oocyte developmental competence was measured. There was no effect of genotype on the distribution of COC grades or on the mRNA abundance of the candidate genes in grade 1 COC. In experiment 2, 20 Fert+ and 19 Fert− cows, ranging from 71 to 189 d in milk, were submitted to superovulation and AI. The uteri of cows that responded to the superovulation protocol (17 Fert+ and 16 Fert− cows) were nonsurgically flushed 7 d postovulation. Recovered embryos were morphologically graded, and mRNA abundance of genes associated with embryo development was measured in grade 1 blastocysts. The response to the superovulation protocol was assessed by counting the number of codominant follicles on the day of AI, which was similar for both genotypes (22.0 ± 9.7 and 19.8 ± 8.2 for Fert+ and Fert− cows, respectively). There was no effect of genotype on the proportion of transferable embryos recovered or on the mRNA abundance of the candidate genes tested in the grade 1 blastocysts. Of the total embryos classified as blastocysts, however, the Fert+ cows tended to have a greater proportion of grade 1 blastocysts compared with Fert− cows (90% vs. 64%, respectively). In conclusion, genetic merit for fertility traits had a no effect on mRNA abundance of the candidate genes that were examined in immature oocytes and cumulus cells and in embryos recovered after superovulation. The observed differences in morphological blastocyst quality following superovulation would suggest that the superior reproductive performance of Fert+ cows could arise during the later stages of embryo development from d 7 until maternal recognition of pregnancy. |
| Databáze: | OpenAIRE |
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