Effect of different processing techniques on motility and acrosomal integrity of cold-stored stallion spermatozoa

Two experiments were conducted to test whether stallion and/or semen proces sing techniques influenced spermatozoal motility and acrosomal status follo wing cold storage. Ejaculates from each of 18 stallions (N=54) were collect ed and split. In Experiment I, a skim milk-glucose extender (SKMG) was adde d to the semen following a 5, 15 or 30 minute delay post-collection. Follow ing each delay, sperm were packaged at a final concentration of 25 million progressively motile sperm per mi (PMS/ml) in a commercially available skim milk-glucose extender (SKMG). In Experiment II, sperm were packaged at con centrations of 25, 50, and 75 million PMS/ml both in the presence and absen ce of seminal plasma (SP) utilizing SKMG and SKMG plus PBS, respectively. I n both experiments, aliquots were cooled, stored, and the percentage of pro gressively motile and acrosome intact spermatozoa were determined at 24 and 48 hours post-collection. In Experiment I, delayed dilution resulted in a lower recovery of PMS, In Experiment II, removal of SP resulted in higher p ercentages of PMS following cold storage. Increasing the concentration of s permatozoa during packaging decreased the percentage of PMS; however, remov al of SP reduced the harmful effects on spermatozoa motility. These data su ggest that reducing the rime that spermatozoa remain in an undiluted state and removal of SP maximize recovery of progressively motile, acrosome-intac t spermatozoa. In addition, individualizing the processing techniques for e ach stallion may enhance spermatozoal survival following cold storage.