Identification of sperm morphometric subpopulations in two different portions of the boar ejaculate and its relation to postthaw quality.
A statistical approach using sequentially principal component analysis (PCA), clustering, and discriminant analyses was developed to identify sperm morphometric subpopulations in well-defined portions of the fresh boar ejaculate. Semen was obtained as 2 portions (the first 10 mL of the sperm-rich fraction and the rest of the ejaculate, respectively) and frozen using a conventional protocol. Before freezing, an aliquot was used for computer-assisted sperm morphometry analysis (ASMA). Postthaw quality was evaluated using computer-assisted sperm analysis (CASA), and an annexin-V/PI assay evaluated sperm membranes. The PCA revealed that 3 variables represented more than 78% of the cumulative variance in sperm subpopulations. The clustering and discriminant analyses, based on 5780 individual spermatozoa, revealed the existence of 4 sperm subpopulations. The relative percentage of these subpopulations varied between boar and ejaculate portions. Linear regression models based on measured morphometric characteristics could account for up to 36% of the percentage of intact sperm membranes postthaw. The ASMA protocol used in our study was useful to detect subtle morphometric differences between spermatozoa, and the combination of this analysis with a multivariate statistical procedure gave new information on the biological characteristics of boar ejaculates that is not given by conventional sperm analysis.
Peña
Fernando J
FJ
Section of Animal Reproduction and Obstetrics, Department of Herd Health and Medicine, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain. fjuanpvega@unex.es
Saravia
Fernando
F
García-Herreros
Manuel
M
Núñez-martínez
Ivan
I
Tapia
Jose Antonio
JA
Johannisson
Anders
A
Wallgren
Margaretha
M
Rodríguez-Martínez
Heriberto
H
D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D016002:Discriminant Analysis; D004542:Ejaculation; D008297:Male; D025341:Principal Component Analysis; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility; D013094:Spermatozoa / Q000145:classification* / Q000166:cytology*; D013552:Swine