Correlation of CASA velocity and linearity parameters with sperm mobility phenotype in turkeys

Since all domestic turkeys are produced through artificial insemination, a measurable sperm characteristic that would be predictive of fertility would allow for the culling of poor males, resulting in improved reproductive ef ficiency. The sperm mobility test (SMT), which quantifies sperm penetration into an Accudenz solution, has been shown to correlate highly with fertili zation potential of individual turkeys. Since this sire-selection test is b ased on the differences in sperm mobility between whole ejaculates from ind ividual males, the objective of this study was to determine whether specifi c sperm velocity parameters would correlate with the SMT and to determine w hether these characteristics could account for phenotypic differences in sp erm mobility observed between males. The SMT was used to rank males within a flock (n = 110) in triplicate and to classify them into high, average, an d low sperm mobility phenotypes on the basis of the sperm mobility index. S everal sperm velocity parameters were evaluated for each male by a computer -aided sperm analysis (CASA) system, the Hobson Sperm Tracker. The types of measurements taken of 200 sperm tracks/ejaculate included the following: c urvilinear velocity (VCL), average path velocity (VAP), straight-line veloc ity (VSL), linearity (LIN), beat-cross frequency (BCF), and mean angular di splacement (MAD). Significant positive correlations were found between VSL, LIN, BCF, and sperm mobility, and a significant negative correlation was s een between MAD and sperm mobility. Subpopulations of sperm that had penetr ated the Accudenz solution were isolated from each mobility phenotype and w ere analyzed by CASA, and significant correlations were again observed betw een VSL, LIN, BCF, and sperm mobility. We conclude that sperm velocity and linearity contribute to overall sperm mobility phenotype and are important characteristics of turkey sperm function.