Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences

Abstract

Contents Dogs have undergone an intensive artificial selection process ever since the beginning of their relationship with humans. As a consequence, a wide variety of well‐defined breeds exist today. Due to the enormous variation in dog phenotypes and the unlikely chance of gene exchange between them, the question arises as to whether they should still be regarded as a single species or, perhaps, they be considered as different taxa that possess different reproductive traits. The aim of this study was therefore to characterize some male reproductive traits, focusing on kinematic characteristics of dog spermatozoa from several breeds. Thirty‐seven dogs from the following breeds were used: Staffordshire Bull Terrier, Labrador Retriever, Spanish Mastiff, Valencian Rat Hunting Dog, British Bulldog and Chihuahua. Semen samples were obtained via manual stimulation and diluted to a final sperm concentration of 50 million/ml, and they were subsequently analysed by the computer assisted semen analysis (CASA‐Mot) ISAS®v1 system. Eight kinematic parameters were evaluated automatically. All parameters showed significant different values among breeds and among individuals within each breed. The fastest sperm cells were those of Staffordshire Bull Terriers and the slowest were recorded in Chihuahuas. The intra‐male coefficient of variation (CV) was higher than the inter‐male CV for all breeds with the Staffordshire Bull Terrier showing the lowest values. When taking into consideration the cells by animal and breed, discriminant analyses showed a high capability to predict the breed. Cluster analyses showed a hierarchical classification very close to that obtained after phylogenetic studies with genome markers. In conclusion, future workers on dog spermatozoa should bear in mind major differences between breeds and realize that results cannot be extrapolated from one to another. Because sperm characteristics are associated with breed diversity, dogs may represent a good model to examine changes in reproductive parameters associated with selection processes.

A New Approach of Sperm Motility Subpopulation Structure in Donkey and Horse

“…The Arabian horse is considered one of the most ancestral, with pure pedigree even if it was shown with the recent study of mitochondrial DNA sequences that there is heterogenicity and great diversity among this breed (52), whereas the pure Spanish horse is considered the first European "warmblood, " a mixture of heavy European and lighter Oriental horses, taking its origin from the Andalusia Spanish region that is recognized as a distinct breed since the 15th century (53). Similar differences have been observed in other species like a bull (54), boar (55), and dog (56), showing how much artificial selection procedures conduces to processes close to the speciation process in natural selection (33).…”

Optimization of CASA-Mot Analysis of Donkey Sperm: Optimum Frame Rate and Values of Kinematic Variables for Different Counting Chamber and Fields

“…In fact, the same results were observed for VC, VSL and VAP on different species like horses, bulls, boars and bucks. Yet, the other parameters were variable depending on the species [24,[27][28][29][30][31][32]. Those differences could be explained by the loading technique that could generate physical forces on the spermatozoa affecting its motility.…”

Sperm Gone Smart: A Portable Device (iSperm®) to Assess Semen Concentration and Motility in Dogs

“…Determination of the Spearman’s correlation coefficients (ρ) were used to assess the relationship between ISAS ® v1 and iSperm ® in the estimation of semen concentration, motility (TM, PM), and other kinematic parameters (VCL, VAP, VSL, STR, and LIN). Specifically, the average value of all semen parameters obtained by the ISAS ® v1 was compared to an increasing number of fields captured and analyzed by the iSperm ® (one field, two fields, three fields, or four fields), as results between each field were already found to be repeatable with the ISAS ® v1 [ 7 ]. Correlations were considered as follows: less than 0.2 negligible association, 0.2 to 0.29 weak association, 0.3 to 0.39 moderate association, 0.4 to 0.69 strong association, and greater than 0.7 very strong association [ 26 ].…”

“…However, hemocytometers are time-consuming and require adequate training [ 4 ], and spectrophotometers are not able to discriminate between spermatozoa and other cells, particles, or debris that may be present in the ejaculate [ 5 ]. For this reason, more advanced and sophisticated equipment, such as computer-assisted semen analyzers (CASA) and the NucleoCounter ® (Chemometec, Denmark), has been developed to objectively evaluate semen motility and concentration [ 6 , 7 , 8 ]. The reliability and technical settings of CASA systems have already been extensively investigated and optimized [ 9 , 10 , 11 , 12 ].…”