Capacitation, acrosome function and chromatin structure in stallion sperm

Abstract

In general, fertility in breeding stallions is lower and more variable than in the other farm animal species, primarily because selection is based on pedigree, looks and/or athletic performance, with little consideration of fertility or fertility potential. Moreover, because the average stallion breeds only a limited number of mares per year and in-field fertility is influenced significantly by nonstallion factors such as management and mare fertility, meaningful fertility data are hard to come-by. Unfortunately, generating usable figures would involve impractically high costs, time and numbers of mares. Instead, a breeding soundness examination (BSE), based on assessments of sperm number, motility and morphological normality and of mating ability, is often carried out with the ostensible aim of identifying animals with the "potential for good fertility". In fact, the BSE generally succeeds only in ruling out those stallions with a very clear reason for sub-fertility, and still fails to identify some seriously sub-fertile animals. Thus, the routine BSE has very limited use as a predictor of subsequent fertility. This paper reviews assays developed for identifying capacitated, acrosome-reacted and DNA-ଝ This paper is part of the special issue entitled "Proceedings of the 4th International Symposium on Stallion Reproduction", Guest Edited by Dr. Edward Squires.* Corresponding author. damaged sperm, and assesses their utility for improving our ability to predict a stallion's fertility prior to the onset of his breeding career.

Sterols in spermatogenesis and sperm maturation

“…The fatty acid composition of sperm during maturation is also highly modifi ed, similar to sterols ( 81 ). These combined events increase membrane fl uidity and facilitate Ca 2+ infl ux into sperm, triggering the acrosomal reaction and fusion with the oocyte ( 82 ).…”

Follicular fluid stimulates capacitation and acrosome reaction in alpaca sperm (Vicugna pacos)

“…Although the zona pellucida would be the inductor responsible for the acrosome reaction, there are other inductors, which can be considered as physiological or non-physiological; the physiological inductors are those that can act naturally during the union of the spermatozoa with the oocyte (Abou-Haila & Tulsiani, 2000;Neild, Gadella, Agüero, Stout, & Colenbrander, 2005).…”

Fifty years of the British Equine Veterinary Association as a facilitator of progress in equine clinical science

“…1982; Kenney and Leeson 1983; Merkt and Klug 1989). Although still useful, it is now recognised that routine BSE has very limited value as a predictor of subsequent fertility and that seminal component analysis can provide better information (Neild et al . 2005).…”

“…Historically, the breeding soundness examination (BSE) was used as a predictive indicator of subsequent stallion fertility (Merkt et al 1982;Kenney and Leeson 1983;Merkt and Klug 1989). Although still useful, it is now recognised that routine BSE has very limited value as a predictor of subsequent fertility and that seminal component analysis can provide better information (Neild et al 2005). Semen morphology, motility, cinematography and in vivo sperm survival tests have historically been crude measurements from which to assess the quality of semen and its relationship to fertility (Bielański 1975;Bielański and Kaczmarski 1979;Voss et al 1981).…”

“…The majority of studies have found multiple links with these tested variables and subsequent fertility; however, there has been a drive to move from subjective basic semen analysis to more objective laboratory-based assessment (Jasko et al 1989(Jasko et al , 1991Jasko 1992;Davis et al 1993;Ball and Mohammed 1995;Casey et al 1997;Gravance et al 1997;Magistrini et al 1997;Brandon et al 1999;Bosard et al 2005;Card 2005;Love 2005;Neild et al 2005;Pesch et al 2006). Flow cytometry has proven to be an ideal method for objectively, rapidly and simultaneously measuring the properties of a large number of sperm.…”