Análise das subpopulações de espermatozoides móveis de carneiros selecionados por critérios etários e andrológicos e submetidos a métodos de conservação seminal

Abstract

The analysis of sperm subpopulations based on kinetics is an important tool for selecting ram for mating and seminal samples subjected to conservation. The aim of the present study was to evaluate, through computerized system analysis (CASA), the influence of Santa Inês ram selection by age and andrological criteria and seminal conservation methods on the number, characterization and distribution of sperm subpopulations. The kinetics of 337,606 sperm distributed in the groups were evaluated: fresh semen from ram without any selection (SF-T); fresh semen from ram selected by andrological examination (SF-S); fresh semen from young ram (SF-S≤18) and adults (SF-S> 18) selected by andrological examination; refrigerated (SR) and frozen (SC) semen from ram selected by andrological examination. Spermatozoa with VCL <100, ≥100 and <200 and ≥200 μm / s were considered as slow, medium and fast, respectively and those with LIN ≥40% and STR ≥70% as linear and progressive. The kinetics data generated were relativized and evaluated by the Two-Step Cluster clustering method. The means of each parameter were compared using the Kruskal-Wallis test to test the differences between the sperm subpopulations (clusters) of the experimental groups. The SF-T and SR-S groups had three subpopulations each; the SF-S>18 group was the most heterogeneous with four; the SF-S≤18, SR and SC groups had only two subpopulations. Among the clusters of the selected ram groups (SF-S, SF-S≤18, SF-S> 18), cluster 1 of SF-S> 18 had the highest values (P <0.05) of most kinetic parameters (VSL, VAP, LIN, STR, BCF and WOB), while cluster 2 of the SF-S≤18 group had the smallest values (P <0.05). Cluster 1 of the SC group had the highest values for VSL, VAP, LIN, STR, BCF and WOB in relation to the SF-S and SR groups (P <0.05). It is concluded that the number, characteristics and proportion of the subpopulations of mobile sperm are influenced by the selection of ram by age and andrological criteria and by the methods of seminal conservation. The subpopulations are more heterogeneous in the fresh semen of adult ram compared to the young ones submitted to the selection and, more homogeneous in refrigerated and frozen seminal samples.