Influence of homologous blood serum on motility and head-to-head agglutination in nonmotile ejaculated bovine spermatozoa

Twenty-five ejaculates, five from each of five different bulls, were used to determine the influence of heat-treated heifer serum on motility, head-to-head agglutination, and acrosomal integrity in aged nonmotile spermatozoa. Spermatozoa from each ejaculate were diluted immediately after collection to 30 x 10 6 spermatozoa/ml in 2.9% sodium citrate and incubated for 8 h at 37°C. As a result of this 8 h incubation, spermatozoal motility was lost and loss of acrosomal integrity was minimal. Immediately following the 8 h incubation, 20% (v/v) homologous heifer serum was added to each sample which was again incubated at 37°C for 8 h. Aliquots were evaluated at 1 min, 2, 4, 6, and 8 h for percentage motile spermatozoa (% MOT), percentage intact acrosomes (PIA), and percentage head-to-head agglutination (HHA). The addition of serum resulted in an immediate (1 min) increase (P