RELATIONSHIPS AMONG IN-VIVO FERTILITY, COMPUTER-ANALYZED MOTILITY ANDIN-VITRO CA(2+) FLUX IN BOVINE SPERMATOZOA

Correlations among computer-assisted spermatozoa motility analyses, Ca 2+ fluxes and in vivo fertility of bovine spermatozoa based on a total of 4482 inseminations were investigated in each of four ejaculates fr om six bulls. The Ca2+ parameters assessed the rate of change in intra - and extracellular Ca2+ in fresh and cryopreserved spermatozoa from t he same ejaculates and were described in another study. Of the seven m otility parameters of cryopreserved semen investigated, all differed s ignificantly among bulls but none were related to the in vivo fertilit y of cryopreserved semen. The amplitude of lateral head displacement, a motility parameter associated with hyperactivation, was positively c orrelated with the intracellular Ca2+ levels and the rate of Ca2+ accu mulation of cyropreserved spermatozoa. The highest fertility was obser ved when initial extracellular Ca2+ for cryopreserved spermatozoa was high and when Ca2+ efflux rates of cryopreserved cells approached the higher efflux rates of fresh spermatozoa. Fertility was reduced when c ryopreserved spermatozoa had initial internal Ca2+ levels greater than those of fresh spermatozoa or when cryopreserved spermatozoa internal ized Ca2+ rapidly. CalCium flux, but not motility, may predict fertili zing capacity of cryopreserved bovine spermatozoa.