115 Sperm motility subpopulations are correlated with fertility in Retinta bulls
E. Teran A , A. Molina B , M. Ramon C , R. Morales B , Y. Pirosanto A , Z. Peña Rodriguez B and S. Demyda-Peyrás DA Instituto de Genética Veterinaria (IGEVET), La Plata, Buenos Aires, Argentina
B Departamento de Genética, Córdoba, Córdoba, Spain
C Centro Regional de Selección y Reproducción Animal de Castilla (CERCYRA), Valdepeñas, Castilla La Mancha, Spain
D Departamento de Producción Animal, La Plata, Buenos Aires, Argentina
Reproduction, Fertility and Development 34(2) 294-295 https://doi.org/10.1071/RDv34n2Ab115
Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Mammalian sperm are characterised by the presence of subpopulations, which have been proposed to have adaptive and functional roles. These subpopulations are characterised by distinct morphometric and kinetic parameters; therefore, their relative abundance could explain changes in fertilisation potential of individuals. Our objective was to establish a relationship between sperm motility subpopulations and fertility in Retinta bulls. Motility of frozen-thawed sperm was assessed after thawing, using computer-assisted sperm analysis (CASA) to evaluate different speed parameters, including curvilinear velocity (VCL), straight line velocity (VSL) and average path velocity (VAP); trajectory indexes, including percentage of linearity (LIN), percentage of straightness (STR), and wobble coefficient (WOB); and two other parameters related to the impulse force of the flagellum at the head: mean amplitude of lateral head displacement (ALH) and beat-cross frequency (BCF). A principal component analysis was performed and the variables VAP, LIN, and ALH were chosen for a non-hierarchical clustering, followed by a hierarchical clustering that finally assigned each sperm to a subpopulation based on the similarity of their values. Four subpopulations with specific kinetic features were determined. Subpopulation 1 were fast and progressive sperm with high VCL, VAP, LIN, and ALH. Subpopulation 2 consisted of medium and progressive sperm, with lower VCL and VAP, and intermediate LIN and ALH. Subpopulation 3 was the slowest and non-progressive sperm and had the lowest values for speed, LIN, and ALH. Finally, subpopulation 4 were hyperactivated and non-progressive sperm, characterised by the highest VCL and ALH values, high VAP, and low LIN. Fertility values of 37 bulls were obtained using the reproductive efficiency parameter (Re) breeding values, estimated using a mixed model implemented in the BLUPF90 family programs from a dataset of 67Â 457 calving records from 11Â 645 individuals. Spearman correlations were performed between percentage of each subpopulation and fertility values. There was a moderate but significant negative correlation (r = −0.33, P < 0.05) between subpopulation 3 (i.e. slow and non-progressive sperm) and fertility. Subpopulation 1 (fast and progressive) had a positive correlation with fertility, although it was not significant (r = 0.2, P > 0.05). In conclusion, proportions of subpopulations could be used to predict fertility of cattle sperm, perhaps including the ability to identify samples with low fertility.
