1,720,977 research outputs found
Gebeliğin ilk trimesterindeki ineklerde embriyonik ve fötal kayıplar
No full textEmbriyonik ve fötal ölümler süt sığırcılığı işletmelerinde hem ekonomik hem de biyolojik verimliliği olumsuz etkileyenkritik problemlerdir. Gebeliğin ilk trimesterindeki gebelik kayıpları, sonraki dönemlerdeki gebelik kayıplarına göre dahasık gözlenir. Her tohumlamada, oositlerin neredeyse tamamı fertilize olurken, oluşan embriyoların yaklaşık yarısı doğumaulaşabilmektedir. İlk trimesterdeki gebelik kayıplarının çoğunluğu (%60 – 87) tohumlama sonrası ilk 28 günde meydanagelirken (erken embriyonik ölüm), ilerleyen günlerde de (28 – 90. günler) (%10 – 35) geç embriyonik veya erken fötalölümler gözlenmektedir. Her ne kadar erken embriyonik ölümlerin prevalansı daha fazla olsa da, geç embriyonik ve erkenfötal ölümler daha yüksek ekonomik zarara neden olmaktadır. Doğum sonrası jinekolojik problemler, uterus içi ve uterusdışı enfeksiyonlar, doğum sonrası erken dönemde yapılan tohumlamalar, tohumlama sayısı, kan progesteron düzeyi,genetik nedenler, ikiz gebelik, ırk ve süt verimi, mevsim ve vücut kondüsyon skoru gebelik kayıplarının en önemlinedenleridir. Gebelik kayıplarının tespitinde, rektal palpasyon, progesteron ölçümleri (P4), ultrasonografi ve gebelikilişkili glikoprotein (PAG) ölçümleri kullanılmaktadır. İlk trimesterde meydana gelen gebelik kayıplarının önlenmesiamacıyla tohumlama sonrası GnRH (gonadotropin salıcı hormon) ve hCG (insan koriyonikgonadotropini) enjeksiyonuile vajina içi progesteron salan gereçlerin kullanımı önerilmektedir.</p
Sütçü ineklerde östrus siklusunun, foliküler gelişimin ve ovulasyonun hormonal kontrolü
No full textSüt sığırcılığı işletmelerinde sürdürülebilir üretim ve verimlilik için en önemli faktörlerden biri döl verimidir. İşletme ölçeğine bağlı olarak, verimliliği artırabilmek için çeşitli yaklaşımlar kullanılmaktadır. Bunlar, seksüel aktivitenin gözlenmesi, sensör teknolojilerinin kullanımı, endokrin ölçümler ve hormon müdahaleleridir. Son elli yıl içinde, işletmelerdeki hayvan sayısının artışı, insan faktöründen kaynaklı kayıpları artırmıştır. Bu nedenle, sürülerde üremenin denetlenmesinde diğer teknolojik yaklaşımlara göre daha ucuz olan hormon uygulamaları yaygın hale gelmiştir. Bu amaçla prostaglandin F2-alfa (PGF2α) analogları, gonadotropin salıcı hormon (GnRH) analogları, progesteron, östradiol (E2), gebe kısrak serum gonadotropini (PMSG), insan koriyonik gonadotropini (hCG) gibi hormonlar veteriner hekimlikte geniş bir uygulama alanı bulmuştur. Üreme hormonlarının analog formlarının kullanımıyla çeşitli östrusun, foliküler gelişimin ve ovulasyonun senkronize edildiği programlar geliştirilmiştir. Bunların en yaygın kullanılanları, hedeflenmiş tohumlama programı, modifiye edilmiş hedef tohumlama programı, ov-synch, presenkronizasyon uygulanan ov-synch, progesteronla desteklenmiş ov-synch, double (çift) ov-synch programlarıdır.</p
The economic optimization of lactation and fertility in dairy cows
No full textLactation and fertility are recognized as fundamental factors that directly influence the sustainability of dairy farming. For farms working with high-yielding dairy cows in particular, maintaining fertility parameters at economically optimal levels is crucial to ensuring the continued viability of such operations. This review underscores the necessity of implementing multifaceted strategies to attain optimal lactation and fertility outcomes, elucidating the requisite steps involved in the execution of these strategies. These include the careful execution of estrus monitoring plans, comprehensive staff training, systematic record-keeping, ensuring optimal fertility parameters, and the judicious interpretation of herd management mathematics. Accurate forecasting and investment necessitate consideration of current market dynamics. Understanding the complex interplay between lactation and fertility in dairy cows is a critical prerequisite for improving overall economic productivity through herd management. To this end, the review presented simulates how the optimization of these two parameters can be achieved and their target values, based on a 100-head herd. While the exemplary model is based on costs in Turkiye, readers can adapt this simulation to calculate according to their own country's standards. Furthermore, the simulation evinced that dairy farms relying solely on milk production incur losses, highlighting the need for diversification to ensure sustainability. In conclusion, the symbiotic relationship between lactation and fertility demands a mathematical approach, and the adoption of these integrated strategies is essential for the sustainability of dairy farms. In this context, profitability can be attained by heeding all cautions regarding the optimization of fertility and lactation, while closely monitoring current market costs
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
Subclinical endometritis in cows: a bibliometric analysis
No full textBovine fertility remains a critical factor in the economic sustainability of livestock operations, with subclinical endometritis (SE) posing a significant challenge. This study presents a comprehensive bibliometric analysis of SE research, aiming to elucidate research trends, influential scholars, and key concepts in the field. A total of 483 articles extracted from the Web of Science (WoS) database managed by Clarivate were analyzed using R Studio and the Bibliometrix package. The analysis reveals that SE research initiated in 1992 but experienced a substantial surge between 2014 and 2016. Theriogenology (n = 82) emerges as the most prolific journal in the field. Marc Drillich (n = 33) stands out as the most productive author, contributing significantly to the body of knowledge. The most frequently occurring keywords include 'cytological endometritis', 'dairy cattle', 'dairy cows', 'endometrial cytology', 'Holstein cows', 'postpartum dairy', 'postpartum uterine', 'repeat breeder', and 'reproductive performance', reflecting the core focus areas of SE research. A Thematic Map Analysis was conducted to visualize research activities and emerging trends. This analysis highlights the evolution of research themes over the examined period, providing insights into the shifting focus of SE studies. The temporal distribution of publications indicates a growing interest in SE, particularly in the last decade, suggesting its increasing recognition as a critical issue in bovine reproductive health. This study is the first comprehensive bibliometric analysis on SE in the veterinary field. By mapping the intellectual structure of SE research, it provides researchers and practitioners with a valuable overview of the current state of knowledge, identifies potential research gaps, and suggests directions for future investigations. Consequently, this analysis can contribute to facilitating studies on bovine SE by guiding researchers in their work
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
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
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