Attempts on freezing the Greylag (Anser anser L.) gander semen

Semen of Greylag (Anser anser L.) ganders was frozen according to a method previously elaborated by the authors for freezing the White Koluda gander semen. Semen was collected from five to eight Greylag ganders, twice a week during three succeeding reproductive cycles, by dorso-abdominal massage. Semen samples were diluted in the ratio of 1:1 or 2:1 (two parts semen: one part diluent) with EK diluent, supplemented by 6% DMF, equilibrated and pre-frozen to -140 degrees C at a rate 60 degrees C/min, before being transferred into liquid nitrogen container. Semen samples thawed in a water bath of 60 degrees C were used for twice a week insemination in a volume of 200 microl. Three Greylag and three White Koluda geese were involved in frozen-thawed semen fertilizing ability test. The reproductive cycle of wild geese lasts usually about 6-7 weeks. The ejaculate volume (30-140 microl) and sperm concentration (10x10(6) to 150x10(6) ml(-1)) are much lower than these of domestic ganders, but spermatozoa morphology is similar, particularly while compared to 1-year-old White Koluda ganders semen. There are about 90% of live spermatozoa and about 30% of live morphologically normal cells in Greylag gander fresh semen. The Greylag gander spermatozoa susceptibility to cryopreservation procedure is as high as in domestic ganders. Dilution ratio 2:1 resulted in higher number of live spermatozoa, which withstood cryoinjury stress. In relation to fresh semen about 60% of spermatozoa remained intact (on the basis of light microscope examination) in the frozen-thawed semen. Insemination of frozen-thawed semen resulted in 37.5% of fertile eggs in Greylag and 25.0% in White Koluda geese. Low fertility rate was caused by an insufficient number of live normal spermatozoa used for insemination (about three million in every dose).