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Early nutritional programming and progeny performance: Is reproductive success already set at birth?
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Repeatability of antral follicle count during early gestation in dairy cattle
No full textIntroduction and Objectives. The number of ovarian antral follicles ≥3 mm in diameter (antral follicle count, AFC) in cattle is highly repeatable in individuals, while being highly variable among animals [1]. Furthermore, AFC is positively associated with ovarian function and fertility in cattle [2]. However, the mean numbers of follicles per month gradually decline from month 7 to month 9 of pregnancy [3]. The ability to phenotypically classify cows based on AFC with a single examination is highly desirable, hence the objective of this study was to investigate if AFC was influenced by pregnancy status and stage of gestation.
Materials and Methods. Transrectal ultrasonography of the reproductive tract was performed as part of the routine reproductive management in a commercial dairy farm on 47 pregnant dairy cows, aged from 1.3 to 4.9 years. Examinations took place before pregnancy establishment (on a random day of the cycle or at the time of artificial insemination, AI±5 days), on the day of pregnancy diagnosis (Day 27-39) and on the day fetal sex assessment (Day 58-68). Each ultrasonography was recorded and subsequently analyzed to determine AFC. The correlations between AFC during different stages of gestation and between AFC and age, parity, body condition score (BCS) were analyzed using ANOVA.
Results. Antral follicle count ranged from 5 to 39 with a mean (±SEM) of 13.21±1.02 and was not influenced by age, parity or days from calving; AFC was not related to pregnancy status, day of gestation or body condition score.
Conclusions. Antral follicle count is a phenotypic biomarker that can be reliably assessed during early gestation in cattle. Cows with high or low numbers of follicles can be reliably identified through transrectal ultrasonography performed on a single examination on a random day during the first trimester of gestation. The variation of AFC within animal during later stages of gestation remains to be determined.
References.
[1] Burns DS, Jimenez-Krassel F, Ireland JL, Knight PG, Ireland JJ. Numbers of antral follicles during follicular waves in cattle: evidence for high variation among animals, very high repeatability in individuals, and an inverse association with serum follicle-stimulating hormone concentrations. Biol Reprod. 2005;73:54-62.
[2] Ireland JJ, Smith GW, Scheetz D, Jimenez-Krassel F, Folger JK, Ireland JL, et al. Does size matter in females? An overview of the impact of the high variation in the ovarian reserve on ovarian function and fertility, utility of anti-Müllerian hormone as a diagnostic marker for fertility and causes of variation in the ovarian reserve in cattle. Reprod Fertil Dev. 2011;23:1-14.
[3] Ginther OJ, Kot K, Kulick LJ, Martin S, Wiltbank MC. Relationships between FSH and ovarian follicular waves during the last six months of pregnancy in cattle. J Reprod Fertil. 1996;108:271-9.
Acknowledments. Funded by the Italian Ministry of University and Research, Rita Levi Montalcini Grant 2010
Evidence That Undernutrition During the First Trimester of Pregnancy Influences Development and Function of the Cardiovascular System in Female Offspring in Cattle
No full textThe cause of the inherently high variation in number of folliclesand oocytes in ovaries of mammals is unknown. However, nutritionduring gestation has a significant impact on postnatal health,but little is known about the role of maternal nutrition onovarian development in offspring. Our previous results showthat number of follicles growing during follicular waves reflectssize of the ovarian reserve (total number of healthy folliclesand oocytes in ovaries) in cattle. Therefore, the aim of thepresent study was to use the bovine model to examine the effectof maternal nutritional restriction from shortly before conceptionto the end of the first trimester of pregnancy (period encompassingthe peak in oocyte numbers in fetus) on the number of antralfollicles during follicular waves in female offspring. Cross-bredbeef heifers (n = 60), of similar age and weight, were randomlyassigned to one of two nutritional treatments: control (C; n= 25) or restricted (R; n = 35) and were individually fed at1.2 or 0.6 of their maintenance (M) energy requirements, respectively,starting 11 days before artificial insemination. Estrous cycleswere synchronized and heifers were artificially inseminatedwith sex-sorted semen from a single sire to increase the proportionof female calves born. Pregnancy diagnosis was carried out onDay 28 using ultrasonography and pregnant heifers (n=28) continuedto receive their respective diets up to Day 110 of gestation.From Day 110 to calving all animals received a 1.4 M diet. Twenty-ninecalves were born (C = 13; R = 16): 23 single female calves,one set of female twins and 4 males. Single female calves bornto mothers in the two groups (C, n=13; R, n=10) were weighedat birth and thereafter every fortnight. Daily transrectal ovarianultrasonography was performed for 10-14 days to count numberof antral follicles ≥ 3mm in diameter during a follicular wavestarting at 7 and 18 weeks of age. Maternal nutrition did notinfluence pregnancy rate on Day 28, gestation length, calf weightat birth, at 7 or 18 weeks of age, or diameter of the largestfollicle in each follicular wave. However, the peak, minimumand mean number of antral follicles ≥ 3mm in diameter in follicularwaves were 60% lower in calves born to heifers in the Restrictedcompared with the Control group. In conclusion, maternal nutritionalrestriction during the first trimester of pregnancy has a significantnegative impact on number of follicles growing during follicularwaves and correspondingly size of the ovarian reserve in calves.Funded by the Irish Department of Agriculture, Fisheries andFood (RSF 06-328) and NRI Competitive Grant nos. 2004-35203-14781& 2007-35203-18178 from CSREES to JJI
Evidence that total number of ovarian follicles >= 3 mm in diameter is moderately heritable in dairy cows
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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