In vitro induction of the acrosome reaction in bull sperm and the relationship to field fertility using low-dose inseminations

摘要

The acrosome reaction (AR) is a prerequisite for normal sperm fertilizing capability and can be studied in vitro after induction by various agents The efficacy of a sperm population to undergo the AR in vivo is expected to influence male fertilizing potential During the past two decades, a number of attempts have been made to relate the in vitro induced AR to field fertility in several species However, to our knowledge, no studies have combined in vitro induction of the AR with the simultaneous detection of sperm viability and acrosomal status using a high-precision flow cytometric technique. Furthermore, large-scale fertility trials using low-dose inseminations are pending In the current study, the relationship between field fertility and the in vitro induced AR was investigated using three ejaculates from each of 195 bulls, 156 Holstein and 39 Jersey bulls (Bos taunts), participating in a progeny test program including low-dose inseminations A range of insemination doses, varying from 20 x 10(6) to 15 x 10(6) sperm/dose, was obtained by a controlled dilution process applied to each ejaculate Different insemination closes were distributed at random among 75,610 experimental first inseminations in 4721 herds and 208 artificial insemination (AI) technicians Simultaneous detection of sperm viability and acrosomal status was achieved using a triple color flow cytometric technique Sperm samples from the bulls displayed a wide range of ability to acrosome react in response to calcium ionophore A23187 Both reproducibility of the AR response after induction and relationship between ability to acrosome react and field fertility was highly dependent on the definition of AR inducibility. Six basic and six combined AR indices were assessed