1,720,965 research outputs found
Characterization of novel reproductive phenotypes in dairy cows
Get PDFA reproductive phenotype that has high variability, repeatability, heritability, and association with fertility could become an excellent candidate for genetic selection to augment fertility in dairy cows. Therefore, the general objective of this research was to evaluate the aforementioned characteristics for five novel reproductive phenotypes in dairy cows, namely gonadotropin releasing hormone (GnRH)-induced luteinizing hormone (LH) response, antral follicle count (AFC), anti-Müllerian hormone (AMH), insulin-like growth factor-1 (IGF-1), and ano-genital distance (AGD). The secondary objective was to identify genetic markers (single nucleotide polymorphisms; SNP) associated with three of the above reproductive phenotypes (AMH, IGF-1, and AGD). The first study was designed to determine the variability and repeatability of GnRH-induced LH responses and the associations among plasma LH, follicle stimulating hormone (FSH), estradiol (E2), and progesterone (P4) concentrations. The association between LH response categories and reproductive outcomes was also tested. I hypothesized that cows have variable responses to GnRH treatment, which are repeatable, and cows with a high LH response to GnRH would have increased likelihood of ovulation and consequently improved reproductive outcomes compared to cows with a low LH response. The GnRH-induced LH responses were normally distributed and highly variable but unrepeatable. Plasma concentrations of LH were positively associated with FSH and E2, and negatively associated with P4. Cows with high LH responses had numerically greater ovulation rate and pregnancy to first artificial insemination (P/AI); however, the association with reproductive outcomes needs to be evaluated in a larger population. The second study was designed to test the repeatability of AFC and AMH concentrations at an unknown stage of follicular growth and at an expected day of follicular wave emergence and the association between AFC and AMH at the above two stages in dairy cows. I hypothesized that the repeatability for AMH would be higher than the repeatability for AFC and the association between AFC and AMH would be strong at both stages. The repeatability was high for AMH and moderate for AFC, and a moderate correlation was found between AFC and AMH at both stages. The third study was designed to evaluate the distribution and variation of AMH, identify factors associated with variation in circulating AMH, determine heritability, establish an optimum AMH threshold predictive of P/AI, examine the relationship between AMH and fertility, and identify SNP associated with the phenotypic variation of AMH in dairy cows. Circulating AMH was positively skewed and highly variable, had a quadratic relationship with parity, moderately heritable, and was associated with numerous genetic markers. The relationships between AMH and fertility outcomes, however, were not significant despite numerical indications of better fertility outcomes in cows with high AMH concentration. The fourth study had similar objectives as the third study, with IGF-1 as the hormone of interest. Circulating concentration of IGF-1 was positively skewed and highly variable, influenced by herd, age, parity, pre-calving body condition score (BCS), and season of sampling. It was also positively associated with P/AI, and linked to a few genetic markers related to previously identified candidate genes of fertility in dairy cows.The fifth study was designed to characterize the distribution and variability of AGD, determine the relationships among AGD, age and height, and evaluate the associations between AGD and P/AI and cumulative pregnancy by 250 d in milk (DIM) within parity groups (first, second, and third + parities) in Canadian Holstein cows. I hypothesized that cows with short AGD, presumably exposed to low in-utero testosterone during fetal life, would have greater fertility than cows with long AGD. The AGD was normally distributed and highly variable, weakly-related to cow age and height, and inversely related to P/AI and pregnancy by 250 DIM in first and second parity cows, but not in third + parity cows. The sixth study, with similar objectives as the fifth study, was conducted in Irish Holstein cows. Despite its normal distribution, high variability, moderate heritability, and weak associations with cow age, height, weight and BCS, the inverse relationship between AGD and fertility found in Canadian Holsteins, was not evident in the Irish Holsteins. Overall, this doctoral thesis provided a deeper understanding of the characteristics of five novel reproductive phenotypes and their potential for selection in dairy cows, and opened new avenues for further research
Fate of cystic ovarian follicles, clinical responses, and pregnancy in dairy cows subjected to Ovsynch and timed artificial insemination, with or without an intravaginal progesterone device
No full textOur objectives were to determine the fate of cystic ovarian follicles (COF), clinical responses, and pregnancy to timed artificial insemination (TAI) in lactating Holstein cows subjected to an Ovsynch protocol, with or without insertion of a progesterone releasing intravaginal device (PRID). Cows diagnosed with at least 1 COF (≥ 25 mm) were given 100 µg of gonadorelin acetate (GnRH; day –10 and day –1), 500 µg cloprostenol (prostaglandin F2α; day –3), and TAI (day 0). Cows randomly received PRID® (n = 49) for 7 days or NO-PRID (n = 62). Transrectal ultrasonography was conducted on days –10, –3, 0, 1, and 11 to monitor ovarian responses and on day 32 for pregnancy diagnosis. Cows were also categorized as low progesterone (LP; n = 50) or high progesterone (HP; n = 61) based on plasma progesterone concentrations (< or ≥ 1.0 ng/ml) or luteal status (presence or absence of luteal tissue) on day –10. Mean (± SEM) diameter of COF was 33 ± 0.6 mm. Although ovarian responses did not differ by PRID treatment, a higher (p = 0.05) proportion of COF in HP compared to LP cows underwent complete luteinization (21 versus 8%) after 1st GnRH treatment. In contrast, the proportion of cows ovulating an existing follicle after 1st GnRH treatment was higher (p = 0.03) in LP than in HP cows (72 versus 54%). No interactions existed between treatment (PRID or NO-PRID) and progesterone categories (LP, HP) in any of the ovarian or endocrine responses. Furthermore, 10% of COF ovulated and 62% of other preexisting follicles ovulated after 1st GnRH treatment. A new follicle was detected (day –3) in 95% of cases and 84% ovulated after 2nd GnRH. Pregnancy per AI did not differ (p = 0.46) between PRID and NO-PRID cows (37 versus 45%). Plasma progesterone at TAI was elevated (p = 0.02) in LP than HP cows (0.7 versus 0.2 ng/ml) and pregnancy tended to be lower (p = 0.13) in LP than in HP cows (34 versus 48%). In summary, cows with COF responded normally to Ovsynch protocol; although incorporating PRID into the protocol was not beneficial, cows with HP status at the start of the protocol tended to have higher pregnancy per AI
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Low-dose natural prostaglandin F2α (dinoprost) at timed insemination improves conception rate in dairy cattle
No full textThe primary objective was to determine if low doses of PGF2α (dinoprost) given intramuscularly (im) concurrent with timed artificial insemination (TAI) would improve conception rates in dairy cattle. A secondary objective was to determine if body condition score (BCS) and parity would influence conception rates, either independently or in interaction with PGF2α treatment. In experiment I, 307 lactating Holstein cows were randomly assigned to receive either 5-mg PGF2α im (PGF2α treated, n = 154) or 0-mg PGF2α (control, n = 153) at TAI (Day 0). Blood samples were obtained on Days −10, −3, 0, and 7 to determine plasma progesterone (P4) concentrations. Pregnancy was confirmed 30 to 32 days after insemination by transrectal ultrasonography. In experiment II, 451 cows were randomly assigned to receive either 10-mg PGF2α im (PGF2α treated, n = 226) or 0-mg PGF2α (control, n = 225) at TAI, and pregnancy was confirmed 45 to 50 days after TAI by palpation per rectum. Pregnancy data were analyzed by CATMOD (SAS). In experiment I, PGF2α treatment, BCS, and parity did not affect conception rate (35.7% vs. 37.0% for PGF2α treated vs. control; P > 0.05). However, in experiment II, conception rates were higher in cows given 10-mg PGF2α than those in control cows (45.8% vs. 36.0%; P < 0.05), in cows with high BCS than in cows with low BCS (52.1% vs. 30.4%; P < 0.01), and in primiparous than in multiparous cows (47.6% vs. 34.4%; P < 0.01), but their interaction with PGF2α treatment did not affect conception rates. In summary, 5 mg of PGF2α given im concurrent with TAI failed to enhance conception rate in lactating dairy cows, whereas 10 mg of PGF2α significantly increased conception rate
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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