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The objective of this study was to evaluate the quality of thawed semen of Holstein bull by computer assisted sperm analysis (CASA). A total sample of 40 straws imported from USA (total bulls = 4; 5 ejaculates per bull; 2 straws per ejaculate) was analysed by CASA using an IVOS. Semen motility was evaluated for kinetics parameters after thawing. The percentage of total mobile spermatozoa (%TMOB) and the percentage of progressive spermatozoa (%PROG) were determined. Several velocities parameters were also determined: average path velocity (VAP, μm/s), curvilinear velocity (VCL, μm/s) and straight-line velocity (VSL, μm/s). Statistical analysis was conducted using SAS software (version 1997). Analysis of variance was carried out using the GLM procedure. DUNCAN test was used to compare
motile variable between bulls. Our results showed that the percentages of TMOB and PROG spermatozoa were higher in the semen of 3 bulls compared to the fourth (% TMOB = 50, 56 and 60 % vs 34 %, p < 0.01; % PROG = 19, 31 and 28 % vs 11 %; p < 0.01). The VAP, VCL and VSL were also higher in the semen of the same 3 bulls compared to the fourth one (VAP = 83, 86 and 109 μm/s vs 70 μm/s, p < 0.01; VCL = 132, 138 and 187 μm/s vs 116 μm/s, p < 0.01; VSL = 70, 75 and 89 μm/s vs 59 μm/s, p < 0.01). Our study suggested that semen from 3 bulls had a good quality compared to the fourth one. It was concluded that their semen can be used in an artificial insemination (AI) program. However, the semen of the fourth bull was not allowed to be utilized in an AI program because it had low kinetics parameters. So, we concluded that imported Holstein bull semen should be assessed by CASA before its use in AI.

semen motility
Holstein bull
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