Analisi computerizzata di seme equino fresco e refrigerato appartenente a tre razze differenti

Several procedures, such as computer-assisted sperm analysis (CASA) (Squires, 2005)performed using the Hamilton Thorne Sperm Analyzer CEROS version 12.1 ), used for this research (www.lsu.com/semen.analysis), have been planned to make more reliable and quick the semen evaluation. The CASA system is used to monitor various parameters, such as motility and velocity, of the sperms in examination. The aim of this work is to use a CASA HTM – CEROS supported by manual analysis methods (semen motility, cellular morphology and viability evaluated using an optical microscope) to value and to compare semen samples collected from stallions of three different breeds. During the 2006-2007 breeding season, semen from Purebred Arabian Horse stallions (8), Quarter Horse stallions (8) and Italian Saddlebred stallions (3), aged between 5 and 20 years, has been evaluated. All the animals, with a proved fertility, were at service in Artificial Insemination Studs in Northern Italy. Five (5) collections into an artificial vagina were performed for each subject. To achieve homogeneous samples according to the set up of the CASA system, semen was diluted with skimmed milk, charged with gentamycin and penicillin G, on the grounds of ejaculate gel-free volume and concentration, to obtain a final concentration of 20 x 106 sperms/ml (Davies Morel, 1999) in a total volume of 3 ml (Ecot et al., 2004). Each semen sample was divided into two aliquots chilled, stored and shipped at 4°C according to standard commercial procedures until the evaluation at 24 and 48 hours after collection (Rota et al., 2004). Before the evaluation samples were warmed in a water bath at 37°C for 10 min. Volume and sperm concentration, percentage of motile and progressive sperms and several motility parameters were evaluated. Statistical analysis was performed to compare the three evaluated breeds using the Student-Newman-Keuls test. The correlation between the parameters obtained with the CASA system and manual sperm vitality and morphology analysis was calculated using the linear (Pearson) correlation test. According to this evaluation, Arabian Horse semen samples were more concentrated and with a lower volume in comparison with the other breeds, as reported by several Authors (Ecot et al., 2004; Elwishy et al., 1982). The same breed showed a statistically significant higher percentage of head sperm abnormalities than the others, according to literature (Hurtgen et al., 1982). It was observed that not only breed differences, but also individual variability affects motility, velocity, vitality and morphologic parameters. Moreover any statistically significant correlation was found between the previous parameters. The individual variability affects also the viability of spermatozoa after storage, but this result is influenced also by other elements, such as the contemporaneous exploitation of these stallions in breeding services and high level athletic performances (Janett et al., 2006). At present it is possible to affirm that the potential stallion fertility rate after artificial insemination (AI) can be estimated from the evaluation of several semen quality parameters, also correlated with cellular lifetime. Furthermore an in-depth semen evaluation provides with important information about the management of semen sampling and processing to optimize its qualities and to reduce negative effects due to incident defects. CASA, supported by manual analysis, confirms to be remarkably useful, going over human error. Anyway it has some restrictions, such as the risk of an incorrect and also unreliable evaluation if the instrument settings are not appropriate.