Effects of cryopreservation on the motile sperm subpopulations in semen from Asturiana de los Valles bulls

Abstract

The aim of this study was to identify different motile sperm subpopulations in ejaculates from an autochthonous bull breed (Bos taurus) and to determine possible modifications in these subpopulations resulting from cryopreservation. Ejaculates were collected and cryopreserved following a conventional protocol. The overall sperm motility and the kinematic parameters of individual spermatozoa were evaluated in fresh ejaculates, after 4 h at 5 8C, and at 0 and 2 h postthaw. A multivariate clustering procedure separated 23,585 motile spermatozoa into four subpopulations: Subpopulation 1 showed medium velocity (VCL: 99.4 AE 17.8 mm/sec) and high progressiveness (LIN: 65.1 AE 14.0%); Subpopulation 2 included spermatozoa with high velocity (VCL: 148.7 AE 25.6 mm/sec) but a nonprogressive trajectory (LIN: 33.1 AE 10.5%); Subpopulation 3 represented slowly motile (VCL: 58.3 AE 24.3 mm/sec) and nonprogressive sperm (LIN: 39.6 AE 18.3%); and Subpopulation 4 included very rapid (VCL: 152.8 AE 25.7 mm/sec) and highly progressive sperm (LIN: 70.9 AE 13.7%). Subpopulation 4 was present in the greatest quantity in fresh ejaculates (36%), but after cooling, it significantly decreased (21%) concomitantly with an increase (P < 0.001) in Subpopulation 2 (from 21% in fresh to 34% in postcooled semen). After freezing and thawing, the overall sperm motility was reduced, mainly due to Subpopulation 2 decreasing from 34% after cooling to 14% after thawing. Differences among bulls in the frequency distribution of spermatozoa within subpopulations were evidenced after thawing by different proportions of spermatozoa in Subpopulations 2 and 4. The current results indicate that a structure of four sperm subpopulations may be a common characteristic of bovine ejaculates and that the cooling phase of cryopreservation seems to be the determinant of postthaw semen quality. #

Computer assisted sperm analysis of fresh and frozen-thawed buffalo semen and their interrelationship

“…There is paucity of literature on velocity distribution of motile sperm of frozen-thawed semen of buffalo bulls, however the present results corroborated with our recent report on crossbred (HF x K) bulls' semen (Patel and Dhami, 2013). Muino et al (2009) confirmed that there was a specific pattern of movement in each subpopulation of bull's ejaculate.…”

Development of automation and control system for the freezing of bovine semen

“…In addition to the freezing rate mentioned above in Figure 1, other freezing rates can be found in different studies by other authors [2] [3] [4] [5] [6]. Among these alternative rates is, for example, a rate of 5°C/min between +5°C and -10°C, and 40°C/min between -10°C and -150°C, as shown in Figure 2, and a faster freezing rate of 60°C/min between +5°C and -120°C as shown in Figure 3 [6].…”

“…Bovine semen can be preserved using experimental freezing systems that use exposure to liquid nitrogen gases or through programmable automated freezing systems that can follow a certain pre-programmed rate of freezing. Most of the published works in relation to cryo-preservation [2] [3] [4] [5] [6] use programmable automated freezing systems that use different freezing rates (thermal descent velocity) as described below:…”

Comparison of different statistical approaches to evaluate morphometric sperm subpopulations in men

“…Sperm subpopulations in semen have been identified in different species on the basis of biochemistry (humans23), function (boars45), motility (stallions;6 red deer;78 dogs;9 bulls;10 rams;111213 and blue foxes14), and morphometry (stallions;15 boars;1617 red deer;718 bulls;1719 brown bears;20 rams;1213172122 Goeldi's monkey;23 and marmosets24). There is increasing evidence that the heterogeneity of these subpopulations has functional relevance.…”