RELATIONSHIPS AMONG FROZEN-THAWED SPERM CHARACTERISTICS ASSESSED VIA THE ROUTINE SEMEN ANALYSIS, SPERM FUNCTIONAL TESTS AND FERTILITY OF BULLS IN AN ARTIFICIAL-INSEMINATION PROGRAM

Frozen semen specimens from 22 Holstein bulls representing a wide rang e of field fertility levels or nonreturn rates (NRR) were used in this study. Semen specimens were thawed at 37 degrees C for a minimum of 3 0 sec, followed by assessment via a routine semen analysis (RSA) and o ther sperm functional tests. The RSA was performed by assessing sperm count, motility and morphological characteristics. Other sperm functio nal tests were performed by assessing the acrosomal membrane integrity , sperm penetration into the cervical mucus and the sperm membrane fun ctional integrity. Following assessment of sperm characteristics, the fertility data of the various bulls were compared to the RSA and the f unctional tests results. Bulls of high and low fertility were similar in terms of sperm count and progressive motility (P>0.05). Other chara cteristics measured by the RSA and functional tests were significantly higher in high fertility bulls (P<0.05). Correlation coefficients amo ng the various sperm characteristics and fertility of bulls were highl y significant (P<0.01). The highest correlation coefficients between s perm characteristics and fertility were obtained for motility (r=0.53; P<0.01), normal morphology (r=0.59; P<0.01) and swollen spermatozoa ( r=0.57; P<0.01). Analysis of specific sperm swelling patterns showed t hat those patterns considered to reflect maximal sperm swelling were i ndicative of high fertility. (C) 1997 by Elsevier Science Inc.