Relationship between bull field fertility and in vitro embryo production using sperm preparation methods with and without somatic cell co-culture

Experiments were designed to compare rates of embryonic development followi ng oocyte exposure to cyropreserved spermatozoa from bulls of varying prove n fertility, utilizing 3 different sperm preparation methods prior to oocyt e introduction. These included 1) sperm co-culture with bovine oviductal ep ithelial cells (BOEC); 2) sperm co-culture with buffalo rat liver cells (BR LC); or 3) control culture in a routine, cell-free culture system. Semen fr om 9 bulls was classified by lifetime 60- to 90-d nonreturn rates as having either (mean +/- SEM) high (n=3) 73.2 +/- 3(a), medium (n=3) 70.3 +/- 2(b) or low (n=3) 65.8 +/- 3(c) field fertility (P-ac< 0.01; P-bc< 0.05). There was no difference in embryo cleavage rates for spermatozoa from the high ( 58 +/- 18%), medium (57 +/- 23%) or low (57 +/- 18%) fertility groups, Deve lopment to morula or beyond of oocytes fertilized with high (53 +/- 30%) or low (58 +/- 27%) fertility semen tended (P<0.10) to be higher than of thos e fertilized with medium fertility (33 +/- 28%) semen. This lack of relatio nship between in vivo fertility and in vitro embryo outcome was consistent across all sperm preparation methods. Therefore, pooled data were used to e valuate the effect of sperm preparation on embryo outcome. There was no dif ference in embryo cleavage rates between BOEC monolayers (51 +/- 22%), BRLC monolayers (60 +/- 20%) and the cell-free controls (60 +/- 17%). Subsequen t embryonic development to compact morula and beyond was higher (P<0.01) wi th the BRLC monolayer treatment (61 +/- 28%) than with the BOEC monolayers (42 +/- 33%) or control culture (39 +/- 24%). In conclusion, these studies suggest that there is no predictive relationship between bull field fertili ty tin the ranges evaluated here) and in vitro embryo cleavage or developme nt rates However, oocytes inseminated with sperm cells co-cultured on BRLC monolayers develop to the morula stage or beyond at a higher rate than oocy tes inseminated with spermatozoa from the BOEC or cell-free system. (C) 199 9 by Elsevier Science Inc.