93 COMPUTER-ASSISTED ANALYSIS OF BOVINE SPERM MOTILITY BEFORE AND AFTER CRYOPRESERVATION
L. Defoin A , A. Granados B , M. Clos B and I. Donnay BA Université Catholique de Louvain, Lovain-la-Neuve, Belgium email: defoin@vete.ucl.ac.be;
B Association wallonne de l’Elevage.
Reproduction, Fertility and Development 16(2) 167-168 https://doi.org/10.1071/RDv16n1Ab93
Submitted: 1 August 2003 Accepted: 1 October 2003 Published: 2 January 2004
Abstract
Sperm cryopreservation causes various types of damage, including membrane injury, oxidative stress, and loss of the acrosome. In cattle, the mortality rate after sperm cryopreservation reaches roughly 50%, and surviving sperm cells have a lower motility and lower fertility than their fresh counterparts. Large variations are also observed between bulls. The aim of this study was to analyse different motility parameters before and after freezing in order to establish correlations. The final objective is to determine, before freezing, parameters that could predict the characteristics of motility after freezing. A computer-assisted sperm analyser (Hobson Sperm Tracker) was used. We analyzed one ejaculate from 30 different bulls before and after freezing (minimum 300 spermatozoa/analysis). Reliable parameters (<10% variation for the same ejaculate) were then selected and included VCL (curvilinear velocity), VAP (average path velocity), MAD (mean angular head displacement), ALH (amplitude of lateral head displacement), STR (straightness of path), and the percentage of motility (%Mot). Linear regressions were established between those parameters before and after freezing. Results are shown in Table 1. The velocity parameters (VAP, VCL, and STR) of the motile sperm were conserved after freezing. Moreover, ejaculates with a high proportion of motile sperm before freezing have, on average, better values for velocity parameters after freezing, while no correlation was found between the percentage of motile sperm before and after freezing. The only parameter of fresh sperm that seems to be correlated with the proportion of motile sperm cells after freezing is MAD (inverse correlation). This could mean that an ejaculate with a high proportion of spermatozoa showing important lateral displacements of the head is more sensitive to cryopreservation. Similarly, a high MAD before freezing was related to a low velocity after thawing. A high MAD could result from a high proportion of capacitated spermatozoa, which is detrimental to their survival and motility. In conclusion, few parameters related to the motility can predict the proportion of motile sperm after freezing. However, by combining several parameters, it seems possible to predict the characteristics of motility of the sperm. Although further investigations are needed, the present evaluation could be of interest to evaluate the freezability of ejaculates, to understand variations between bulls, or to set up new freezing protocols.
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