Relationship between Fertility Traits and Kinematics in Clusters of Boar Ejaculates

Abstract

The aim was to determine the relationship between kinematic parameters of boar spermatozoa and fertility rates of sow, as well as to assess the effect of sperm clusters on the fertility capacity of the ejaculate. Semen samples were collected from 11 sexually mature boars. Samples were analyzed by an ISAS®v1 CASA-Mot system for eight kinematic parameters. Ejaculate clusters were characterized using multivariate procedures, such as principal factors (PFs) analysis and clustering methods (the k-means model). Four different ejaculate clusters were identified from two kinematic PFs which involved linear trajectory and velocity. There were differences (p < 0.05) between the sperm kinematic variables by sire line. There was no statistical difference (p > 0.05) between dam lines and ejaculate clusters in fertility variables. The discriminant ability of the different kinematics of sperm variables to predict litter size fertility was analyzed using receiver operating characteristics (ROC) curve analysis. Curvilinear velocity (VCL), average path velocity (VAP), amplitude of lateral head displacement (ALH), and beat-cross frequency (BCF) showed significant, albeit limited, predictive capacity for litter size fertility variables (range: 0.55–0.58 area under curve, AUC). The kinematic analysis of the ejaculates in clusters did not have a predictive capacity for litter size variables.

Predicting fertility from sperm motility landscapes

“…Previous work on sperm motility used K-means and similar multivariate classification methods, leading from two to 11 clusters 4 , 17 . These studies put their focus on identifying sperm subpopulations and their possible biological functions.…”

“…While literature points out some association between motility parameters and fertility (e.g., ref. 14 – 17 ), most reports acknowledge poor predictability and practical application. This is so by a number of reasons.…”

Influence of Fat-Soluble Vitamin Intramuscular Supplementation on Kinematic and Morphometric Sperm Parameters of Boar Ejaculates

“…When comparing boars within treatment, it was possible to observe differences between boars for all treatments of the experiment, even when they presented the same breed composition. These differences between boars can be explained by considering the ejaculate of the same boar as a heterogeneous population ( 29 ), or by the different subpopulations within each ejaculate ( 63 ) that could generate significant variability in motile sperm and kinematic patterns ( 64 ). These differences could be related to factors such as age ( 43 ), genotype ( 65 ), nutrition ( 22 ), temperature ( 11 ), and health status ( 66 ).…”

“…Ejaculates were collected in the morning, 1 time per week, using the “gloved-hand” technique ( 28 ) and immediately placed in a water bath at 37°C at the farm laboratory. In all cases, the sperm-rich fractions were collected and diluted with a commercial extender (Zoosperm ND5; Import-Vet, Barcelona, Spain) using the procedure described by Barquero et al ( 29 ). Insemination doses contained a concentration of 3.7 ± 1.3 × 10 9 spermatozoa.…”

“…The concentration was measured with Spermacue (Minitube, GmbH, Tiefenbach, Germany) following established protocols ( 30 ). Samples were stored at 17°C and were transported to the laboratory under the same refrigerated conditions (17°C) used for commercial distribution according to Barquero et al ( 29 ). Semen samples (1 ml) were placed in an Eppendorf ® tube (Sigma-Aldrich, St. Louis, MO, USA) and remained at 37°C for 30 min before evaluations.…”