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There is increasing interest in the use of sex-sorted semen especially in certain breeds. After artificial insemination (AI) with fresh sex-sorted semen, pregnancy rates between 10% and 60% have been reported (Buchanan. et. al. Theriogenology. 2000; 53:1309-1321; Lindsey. et. al. Equine Veterinary Journal. 2002; 34:128-132; Lindsey. et. al. Animal Reproduction Science. 2005; 85:125-130). With sex-sorted frozen thawed semen the reported pregnancy rates are lower ranging from 0 – 27% (Linsey. et. al. Equine Veterinary Journal. 2002; 34:121:127; Clulow. et. al. Animal Reproduction Science; 2007; 108:287-297; Gibb. et. al. Equine Veterinary Journal. 2016; 49(2): 160-166). Limited studies have shown that although pregnancies can be achieved with ICSI using frozen-thawed sex sorted semen, cleavage rates are low (20% -30%) (Carnevale. et. al. Reproduction, Fertility, Development. 2008. 21(1) 228; Colleoni.et.al. Reproduction Fertility, Development. 2008, 21(1):228-229). Since those reports, further improvements in sex-sorting stallion semen by flow cytometry have been made. The semen from a polo stallion of proven fertility was collected and the raw semen parameters assessed with a phase contrast microscope, NucleoCounter SP-100 (Chemometec, Allerod, Denmark) and IVOS CASA system (Hamilton Thorn IVOS, Massachusetts, USA). The sample was then centrifuged through EquiPure (Nidacon, Mölndal, Sweden), the pellet recovered and extended in media for final sorting by flow cytometry (Cogent, Chester UK). The semen was selected for the X-chromosomeand frozen into 0.25ml straws with a concentration of 5 million sperm per straw. Post thaw results of the semen were 17.1% total motility, 10.1% progressive motility, 26.2% non-viable sperm and purity of 95%. The oocytes from four different mares were fertilized with the sex-sorted semen resulting in 3 embryos. Two embryos were thawed and transferred into suitable recipients. One transfer resulted in a pregnancy due in April 2023. The third embryo has not been transferred yet. The results of ICSI using frozen sex-sorted semen were compared to conventionally frozen semen used for ICSI in 23 commercial OPU-sessions (summary Table 1). There were no significant differences between ICSI with sex sorted semen from one stallion and the controls (χ2 test, P≤0.05). This study shows that frozen-thawed sex-sorted semen can be successfully used for ICSI. However, further improvement of the flow cytometry and cryopreservation protocols are needed to improve the post-thaw quality of semen. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Estudios de Filosofía is the property of Universidad de Antioquia, Instituto de Filosofia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of distance variables expressing the likelihood of species occurrence at a given site in relation to the distance to observed species presence is demonstrated to improve species distribution models, especially when combined with environmental variables which relate species occurrence to the environmental habitat characteristics. In this study we developed models to predict the spatio-temporal distribution of Culicoides imicola , which is the main transmission vector for the bluetongue virus in the Mediterranean region. We investigated (i) the importance of the environmental habitat characterization by means of bioclimatic variables, (ii) the effect of different distance variables to model the dispersal process, and (iii) the suitability of two different parameter identification procedures to determine the distance variables for species distribution modeling. Results showed that niche-based species distribution models, which only use environmental data, could estimate the occurrence of Culicoides imicola accurately, given that environmental data of the period of high species abundance (April until October) was included. The use of these models may therefore be hampered for predictive risk assessment aiming to estimate the probabilities and magnitude of undesired effects caused by the occurrence of C. imicola . Species distribution models accounting for species dispersal in addition to the environmental habitat characteristics, i.e. hybrid models, did provide accurate predictions of C. imicola distributions well before the onset of the season of high species abundance. A Gaussian or negative exponential function of the distance to presence locations was most suitable to model insect dispersal. The enhanced predictive capacity of these models potentially leads towards an increased model applicability in risk assessment and disease control. [ABSTRACT FROM AUTHOR]