The aim of the study was to verify the quality of ram semen, frozen in 1982-1983, from the historical collection of the Bank of Biological Material of the National Research Institute of Animal Production. A total of 18 ejaculates from 3 Świniarka type rams were analyzed to assess sperm motility (subjectively), total motility, progressive motility, sperm concentration (CASA), membrane integrity (SYBR-14/PI) and chromatin structure (SCSA). In order to determine sperm fertilizing ability 49 ewes were intracervically inseminated (200×106 sperm per AI) with frozen- thawed semen 12 and 24 hours after detection of estrus. Sperm motility parameters, membrane intact spermatozoa and DFI did not differ among the analyzed rams. Spermatozoa concentration was significantly higher for ram no. 2 than for rams no. 1 and 3. The lambing rates (27.3 to 36.0%) did not differ significantly for individual rams. The ram semen, which had been stored for around 40 years, showed satisfactory quality and fertilizing capacity, allowing for its use in artificial insemination.

The aim of the study was to investigate the effect of soybean lecithin as a substitute for egg yolk in milk and tris based extenders in ram semen cryopreservation. Twenty ejaculates were col- lected from four healthy, mature Wrzosówka rams (2-3 years of age). Each ejaculate was divided into four equal aliquots and diluted with four different extenders: 1) milk extender containing 5% egg yolk, 2) milk extender containing 1.5% soybean lecithin, 3) tris extender containing 20% egg yolk, 4) tris extender containing 1.5% soybean lecithin. Extended semen was loaded into 0.25 ml French straws, cooled and frozen in liquid nitrogen vapor. Total motility, curvilinear velocity, plasma membrane integrity and fertilizing ability of sperm were assessed after thawing. Total mo- tility was lower (p<0.05) in tris-soybean lecithin extender when compared to other extenders. Curvilinear velocity was higher (p<0.05) for spermatozoa cryopreserved in milk-soybean lecithin extender compared to other extenders tested. For the percentage of live sperm no significant difference was observed between extenders. The lambing rate were higher (not statistically signifi- cant) in ewes inseminated with semen doses frozen in milk-soybean lecithin extender (42.9%) than in the tris-egg yolk extender (16.7%). In conclusion, replacing the egg yolk with soybean lecithin was effective in milk but not in tris extender.