Appraisal and standardization of curvilinear velocity (VCL) cut‐off values for CASA analysis of Japanese quail (Coturnix japonica) sperm |
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| Authors: | U Farooq IA Malecki M Mahmood GB Martin |
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| Affiliation: | 1. School of Animal Biology M085, Faculty of Science, The University of Western Australia, Crawley, WA, Australia;2. The UWA Institute of Agriculture M082, The University of Western Australia, Crawley, WA, Australia;3. Department of Poultry Science, Sub Campus Toba Tek Singh, University of Agriculture Faisalabad, Pakistan;4. Department of Animal Sciences, University of Stellenbosch, Matieland, South Africa;5. Department of Math, Government College University, Faisalabad, Pakistan |
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| Abstract: | One of the basic steps in objective analysis of sperm motility is the subdivision of a motile sperm population into slow, medium and rapid categories based on their velocity. However, for CASA analysis of quail sperm, the velocity values for categorization of slow, medium and rapid sperm have not yet been standardized. To identify the cut‐off values of “velocity curvilinear” (VCL) for quail sperm categorization, we captured and analysed 22,300 tracks of quail sperm using SCA®‐CASA. The median and mean VCL values were 85 and 97 μm/s. To define the VCL cut‐off values, we used two methods. In the first, we identified the upper (rapid sperm) and lower (slow sperm) cut‐off values using: (i) median VCL ± 25% or ± 50% or ± 75% of median VCL value; (ii) first and third quartile values of VCL data (i.e. 25% cut‐off setting); and (iii) 33% and 66% of VCL data. Among these settings, sperm categories and their corresponding motility characteristics recorded using the “25%” setting (i.e. slow ≤36 ≤ medium ≤154 ≤ rapid) were found the most realistic and coherent with male ranking by fertility. In the second method, we calculated heteroscedasticity in the total VCL data using PCA and the two‐step clustering method. With this approach, the mean of the high and low clusters was 165 and 51 μm/s, respectively. Together, the mean from two methods suggested that, for SCA®‐CASA categorization of quail sperm, sperm should be classed as “rapid” at VCL ≥160 μm/s and “slow” at VCL ≤45 μm/s. |
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| Keywords: | CASA sperm evaluation VCL cut‐off values sperm categorization sperm velocities |
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