1,721,033 research outputs found
Preliminary results on the composition of oviductal fluid in buffalo species.
No full textAlthough the multi-step process of IVEP has been successfully used for producing morulae/blastocysts and pregnancies in buffalo, the efficiency, in terms of transferable embryos (TE) and development to term, is still very low. We believe that IVEP efficiency in buffalo may be greatly improved by minimizing the stress before IVM and identifying the causes of the lower cleavage rate. It is still not clear if the lower cleavage rate is due to problems occurring during IVM or IVF. Furthermore it is advisable to carry out new studies in order to better understand the physiology and the metabolism of buffalo embryos, that may have different culture requirements compared to bovine embryos. The characterization of buffalo oviductal fluid in different stages of the estrus cycle would allow the optimization of the IVEP system, because the oviduct represents the microenvironment in which the processes of fertilization and early embryo development happen. The production of oviductal fluid is affected by the phase of the estrous cycle. In fact, when progesterone levels are higher, the oviductal fluid volume is lower than 1ml, whereas definitely higher values are recorded during the follicular phases of the cycle. Anyway, the volume of oviductal fluid collected in buffalo, both in follicular and luteal phases of the cycle, is greatly lower than those reported in bovine and in swine. The concentration of this metabolite assessed during the estral phase (0.06 mmol/L) resulted similar to that recorded in bovine. A different trend is recorded for lactate and pyruvate: in fact similar values were observed both in luteal and estral phases. Few differences were observed regarding to the ionic components of the Ampullary fluid. The levels of sodium, potassium and calcium did not show any significant differences among the phases, but resulted highly correlated to the typical levels recorded in the blood in buffalo. These preliminary results on the quantity and the characteristics of the oviductal fluid in buffalo underlined that this species is different from others, although the trend reported for several substances is similar. The lower production of oviductal fluid and metabolites recorded in the ampulla may be due to anatomic-functional causes. However, further studies are needed in order to better evaluate the protein composition and concentration. These studies would be furthermore utilized for the preparation of laboratory media specific for buffalo species
Factors affecting embryonic implantation in buffalo
No full textIn mammalians following fertilization and fusion of gametes, the zygote undergoes subsequent mitotic divisions, which determines the formation of the blastomeres. These phenomena occur initially into the oviduct and subsequently into the uterus. Usually, embryos reach the uterus at morula stage and undergone continue divisions until blastocyst formation. The rupture of zona pellucida represents the event for a new stage of the embryo. In this moment the hatched blastocyst survival is strictly dependent by the uterine environment and the conceptus exposes the surface of trophectoderm directly to the uterus. Starting from this moment, the cross-talk between mother and embryo is fundamental in order to guarantee embryonic development and attachment. Several factors can affect these stages in all mammalian species, leading to the phenomenon of embryonic and foetal mortality. Buffalo species, because of its reproductive characteristics, can show a high incidence of embryonic mortality, in particular in some periods of the year. In this review the main factors involved in these phenomena in buffalo will be analysed and discussed
Effect of space availability on productive and reproductive performances in buffalo cows
No full textThe effects of space availability on productive and reproductive performances have been evaluated in buffalo cows. The trial was carried out on 124 lactating buffaloes (69±84 days in milk) equally divided in two experimental groups (group 1 and group 2) with different space availability (15 vs 20m2/ head). Daily milk production was recorded in each group and a sample of milk was monthly analysed for fat and protein contents. Furthermore, fertility and intercalving and start trial-conception (number of days from the beginning of the trial until conception) intervals were also evaluated. Statistical analysis was performed by ANOVA with repeated measures for productive parameters and by Student’s t Test for intercalving and start trial-conception intervals. Buffaloes in Group 2 showed higher (P<0.05) milk production in both the initial (74 to 104 days in milk) and final (around 230 days in milk) phases of the lactation curve compared to animals in Group 1. No differences emerged for qualitative characteristics of milk and reproductive parameters. In conclusion the increase of space availability improve animal milk yield in buffalo cows while reproductive performances are not modified
Effect of GnRH administration on pituitary response in buffalo.
No full textThe aim of this study was to verify the pituitary response to a GnRH administration on day 6 post-insemination in buffalo. The trial was carried out in January on 21 pluriparous Italian Mediterranean Buffaloes (DIM=118±50 days). The animals were synchronized by using the Ovsynch-TAI Program (Neglia et al., 2003) and inseminated twice, 16 and 40 hours after the last administration of GnRH. Blood samples were collected just before GnRH administration (time 0 – T0) and 30 minutes (time 1 – T1), 3 hours (time 3 – T3) and 24 hours (time 24 – T24) after administration, in order to determine LH, FSH and E2 levels. The administration of 12 μg of Buserelin acetate (Figure 1) significantly (P<0.01) increased LH and FSH blood levels after 30 minutes (T1) and after 3 hours (T3), lowering to the initial values after 24 hours (T24). Therefore the use of GnRH or its analogous represents a good tool in order to increase P4 levels in buffalo species
Going 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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