Reproductive hormones and follicular growth during development of one or multiple dominant follicles in cattle.

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RNA-Seq analysis uncovers transcriptomic variations between morphologically similar in vivo- and in vitro-derived bovine blastocysts

<p>Abstract</p> <p>Background</p> <p>A valuable tool for both research and industry, in vitro fertilization (IVF) has applications range from gamete selection and preservation of traits to cloning. Although IVF has achieved worldwide use, with approximately 339,685 bovine embryos transferred in 2010 alone, there are still continuing difficulties with efficiency. It is rare to have more than 40% of fertilized in vitro cattle oocytes reach blastocyst stage by day 8 of culture, and pregnancy rates are reported as less than 45% for in vitro produced embryos. To investigate potential influences in-vitro fertilization (IVF) has on embryonic development, this study compares in vivo- and in vitro-derived bovine blastocysts at a similar stage and quality grade (expanded, excellent quality) to determine the degree of transcriptomic variation beyond morphology using RNA-Seq.</p> <p>Results</p> <p>A total of 26,906,451 and 38,184,547 fragments were sequenced for in vitro and in vivo embryo pools, respectively. We detected expression for a total of 17,634 genes, with 793 genes showing differential expression between the two embryo populations with false discovery rate (FDR) < 0.05. There were also 395 novel transcribed units found, of which 45 were differentially expressed (FDR < 0.05). In addition, 4,800 genes showed evidence of alternative splicing, with 873 genes displaying differential alternative splicing between the two pools (FDR < 0.05). Using GO enrichment analysis, multiple biological pathways were found to be significantly enriched for differentially expressed genes (FDR < 0.01), including cholesterol and sterol synthesis, system development, and cell differentiation.</p> <p>Conclusions</p> <p>Thus, our results support that IVF may influence at the transcriptomic level and that morphology is limited in full characterization of bovine preimplantation embryos.</p

Endocrine and metabolic differences between Bos taurus and Bos indicus cows and implications for reproductive management

Abstract Based on the considerable differences in ovarian morphology and function, as well as circulating hormones and metabolites between Bos indicus (B. indicus) and Bos taurus (B. taurus), researchers are using this acquired knowledge to optimize protocols for fixed-time artificial insemination (FTAI), and production of in vivo derived embryos by multiple ovulation or by in vitro embryo production (IVP). In B. indicus, at the time of follicle deviation, the dominant follicle is smaller and acquires ovulatory capacity at a smaller diameter than B. taurus. Moreover, despite ovulating smaller follicles and having smaller corpora lutea (CL), circulating concentrations of estradiol (E2) and progesterone (P4) are greater in B. indicus than B. taurus. These physiological differences may be related to greater circulating cholesterol, insulin and IGF1 in B. indicus than in B. taurus. For both genetic groups there is a negative relationship between circulating P4 and ovulatory response to the first GnRH treatment of a fixed-time AI (FTAI) protocol. Moreover, despite lower clearance rates of steroid hormones in B. indicus than B. taurus, the dose of 2 mg estradiol benzoate seems to be the most effective either for Nelore (B. indicus beef), Angus (B. taurus beef), or Holstein (B. taurus dairy) cows at the initiation of an E2/P4-based FTAI protocol to optimize synchronization and pregnancy per AI (P/AI). Several studies have shown that only one recommended dose of PGF2α at a FTAI protocol may be insufficient for adequate luteolysis in B. indicus and B. taurus. When submitted to multiple ovulation and embryo transfer, B. indicus cows and heifers need less FSH than B. taurus to achieve superovulation. Moreover, IVP has been more successful in B. indicus than B. taurus due to greater antral follicle count and anti-mullerian hormone, and better oocyte quality

The role of the exit in the initial screening of investment opportunities: The case of business angel syndicate gatekeepers

The exit process has been largely ignored in business angel research.. The practitioner community identifies the difficulty in achieving exits as the most pressing problem for investors. This has been attributed to the failure of investors to adopt an exit-centric approach to investing. The validity of this claim is examined via a study of the investment approach of 21 ‘gatekeepers’ (managers) of angel groups in Scotland and Northern Ireland. Most gatekeepers say that they do consider the exit when they invest. However, this is contradicted by a verbal protocol analysis which indicates that the exit is not a significant consideration in their initial screening process. The small number of exits achieved by the groups is consistent with the general lack of an exit-centric approach to investing. Only three groups exhibit evidence of a strong exit-centric approach to investing. The lack of exits may have a negative impact on the level of future angel investment activity

The physiology and impact on fertility of the period of proestrus in lactating dairy cows

Abstract In cattle, proestrus begins with the initiation of luteolysis and ends with initiation of estrus and the GnRH/LH surge. This period is marked by a dramatic decrease in circulating progesterone (P4) that reaches a nadir by about 36-48 h in cows undergoing natural or prostaglandin F2α (PGF)-induced luteolysis. Inadequate luteolysis is a cause of reduced fertility particularly in timed AI programs with small elevations in circulating P4 reducing fertility. Increasing circulating estradiol (E2) during proestrus is dependent on presence, size, and function of the dominant follicle and this varies during natural proestrus, due to whether animals have two or three follicular waves, and during PGF-induced proestrus, according to stage of the follicular wave at time of PGF treatment. Inadequate circulating E2 can limit fertility and increase pregnancy loss in some specific circumstances such as in cows with low BCS and in cows during heat stress. Thus, studies to optimize the length of proestrus and the concentrations of E2 and P4 during proestrus could produce substantial improvements in fertility and reductions in pregnancy loss

Supplementation with estradiol-17 beta before the last gonadotropin-releasing hormone injection of the ovsynch protocol in lactating dairy cows

The aim of this study was to determine whether an increase in circulating estrogen concentrations would increase percentage pregnant per artificial insemination (PP/AI) in a timed AI protocol in high-producing lactating dairy cows. We analyzed only cows having a synchronized ovulation to the last GnRH of the Ovsynch protocol (867/1,084). The control group (n = 420) received Ovsynch (GnRH - 7 d - PGF2α - 56 h - GnRH -16 h - timed AI). The treatment group (n = 447) had the same timed AI protocol with the addition of 1 mg of estradiol-17β (E2) at 8 h before the second GnRH injection. Ovarian ultrasound and blood samples were taken just before E2 treatment of both groups. In a subset of cows (n = 563), pressure-activated estrus detection devices were used to assess expression of estrus at 48 to 72 h after PGF2α treatment. Ovulation was confirmed by ultrasound 7 d after timed AI. Treatment with E2 increased expression of estrus but overall PP/ AI did not differ between E2 and control cows. There was an interaction between treatment and expression of estrus such that PP/AI was greater in E2-treated cows that showed estrus than in E2-treated or control cows that did not show estrus and tended to be greater than control cows that showed estrus. There was evidence for a treatment by ovulatory follicle size interaction on PP/AI. Supplementation with E2 improved PP/ AI in cows ovulating medium (15 to 19 mm) but not smaller or larger follicles. The E2 treatment also tended to improve PP/AI in primiparous cows with low (S2.5) body condition score, and in cows at first postpartum service compared with Ovsynch alone. In conclusion, any improvements in PP/AI because of E2 treatment during a timed AI protocol appear to depend on expres sion of estrus, parity, body condition score, and size of ovulatory follicle

Business angel exits: A theory of planned behaviour perspective

Although there are a handful of studies on business angel investment returns, the business angel literature has given little or no attention to exits and the exit strategy. This is surprising given that a primary objective of investing is to achieve a capital gain through some form of liquidity event. Using the theory of planned behaviour (TPB) as an interpretative heuristic, we examine how exits happen: specifically, what are the motivations to seek an exit and to what extent are they planned or opportunistic? Based on multiple case studies in which business angels were invited to tell the story of their most recent exit(s), the evidence suggests that the majority of liquidity events are the outcome of planned behaviour. We propose a typology of angel-backed investment exits as the basis for identifying future directions for research and developing practical advice to angels on effective business practices

Fertilization rate and embryo quality in superovulated Holstein heifers artificially inseminated with X-sorted or unsorted sperm.

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Antecedents and consequences of effectuation and causation in the international new venture creation process

The selection of the entry mode in an international market is of key importance for the venture. A process-based perspective on entry mode selection can add to the International Business and International Entrepreneurship literature. Framing the international market entry as an entrepreneurial process, this paper analyzes the antecedents and consequences of causation and effectuation in the entry mode selection. For the analysis, regression-based techniques were used on a sample of 65 gazelles. The results indicate that experienced entrepreneurs tend to apply effectuation rather than causation, while uncertainty does not have a systematic influence. Entrepreneurs using causation-based international new venture creation processes tend to engage in export-type entry modes, while effectuation-based international new venture creation processes do not predetermine the entry mod