The first experiment was designed to determine if the antigenicity of egg yolk diluter could be eliminated by the addition of specific antibodies. Two virgin heifers were immunized with 20% yolk - 2.1% citrate - 7% glycerol with penicillin and streptomycin. Non-immune serum and immune sera having titers of 1:640 and 1:2560 were collected and frozen. Serum antibody titers were determined by the passive hemagglutination test. Utilizing equivalent proportions test it was determined that 80 volumes of anti-egg-yolk-diluent sera titered 1:2560 was necessary to neutralize 1 volume of 20% egg yolk diluent.

The second experiment examined the effect of immune sera against egg yolk diluter upon the viability of bovine spermatozoa in that diluter. Using a split-ejaculate technique, 7 ejaculates from 3 bulls were diluted in egg yolk-citrate diluter or skimmilk diluter, cooled, glycerolated and stored at S°C. On the first day after semen dilution, complement-fixed immune serum titered 1:2560, 1:640 and non-immune serum were added to aliquots of diluted semen (1:9 v/v). Aliquots of each diluter without serum served as controls. Each treatment was evaluated immediately after addition of serum and again after 48 hr storage at 5°C. Percent intact acrosomes, percent motility and percent agglutination were measured from unfixed smears at 0, 3, 6 and 9 hr of incubation at 37°C. Both immune and non-immune serum treatments were characterized by head to head agglutination. Within both diluters, there were no significant differences in motility or intact acrosomes due to immune and nonimmune sera. However, all serum treatments were significantly higher (P < .01) in motility and percent intact acrosomes than the non-serum controls. The overall percent intact acrosomes across all hours, days and diluters were 77.9, 81.1, 81.2 and 81.7 for control, non-immune serum, 1:640 serum and 1:2560 serum, respectively. Differences in the percent head to head agglutination were not due to anitbody titer of the serum.