Investigations on a cryopreservation protocol for long-term storage of psittacine spermatozoa using cockatiel semen as an example.

The aim of the present study was the establishment of an effective protocol for cryopreservation of psittacine semen. Therefore, pooled semen samples of 30 cockatiels (Nymphicus hollandicus) were diluted with modified Lake diluent (1:4), partitioned into four equal parts. Three portions were mixed with three cryoprotectants (dimethylacetamide, dimethyl sulfoxide, glycerol) in 4%, 8% and 12% final concentration, respectively, whereas the 4rth part served as control. Altogether, 96 incremental diluted semen samples were obtained for investigation. Each cryoprotective agent (CPA) in each final concentration was evaluated regarding sperm motility immediately after dilution and another four times every 30 min. Sperm viability was evaluated 0 and 120 min after dilution using the fluorescence stain SYBR® Green/propidium iodide. Sperm morphology was evaluated 0 and 120 min after dilution using eosin B stains. Glycerol demonstrated a lethal effect on cockatiel spermatozoa in all concentrations, whereas dimethylacetamide (DMA) in 8% final concentration proved to have the least adverse effect on semen parameters. Comparison of quick and slow freezing methods using DMA 8% revealed significantly higher rates of viable and motile spermatozoa after computer-controlled rate freezing. Two insemination experiments resulted in an egg fertility rate of 92.59% and 67.65% after artificial insemination with freshly collected semen samples, compared to 30.77% and 18.00% egg fertility rates using frozen/thawed semen. Altogether, 12 chicks hatched out of eggs inseminated with cryopreserved semen. To our knowledge, this is the first time for cockatiels to be successfully reproduced after artificial insemination using cryopreserved semen.

Utilization of frozen-thawed epididymal ram semen to preserve genetic diversity in Scrapie susceptible sheep breeds.

The European Union has introduced transmissible spongiform encephalopathy (TSE) resistance breeding programmes for several sheep breeds to cope with the genetic susceptibility to Scrapie infections. Due to the different allele frequencies among breeds, strong selection for ARR alleles is associated with a loss of genetic diversity in small populations and in larger populations with unfavourable ARR allele frequencies. To ensure maintenance of genetic diversity, an adhoc cryopreservation programme was initiated employing epididymal sperm from 109 rams representing 16 different breeds within one breeding season. Epididymal semen was chosen for this adhoc programme because time consuming training of rams for ejaculated semen collection via an artificial vagina was not possible. Prior to freezing, average sperm motility was 79.7% and acrosome integrity was 93.7%. After freezing, these levels were decreased to 60.5 and 72.8%, respectively. An insemination trial using frozen-thawed epididymal semen resulted in a lambing rate of 87.5%. Results show that this semen preservation method is robust and efficient and associated with high fertility. It may also be useful for other animal species.

[Preservation of genetic variation in domestic animals using biotechnical methods]. / Erhaltung genetischer Vielfalt bei Nutztieren durch biotechnologische Verfahren.

The conservation of endangered breeds as live animals is at present the main national strategy of the government and breeding organizations to maintain genetic diversity. Fourty-three breeds and some old strains of cattle, pig, sheep, goat and horses are currently involved. Cryopreservation and banks for sperm, embryos or DNA are another type of genetic material which could subsequently be used for breeding and production in agriculture. Present semen banks involve 9 endangered cattle breeds and also a small amount of deep-frozen sperm of some endangered sheep and horse breeds. Only 2 embryo banks are established in government projects for cattle breeds Murnau-Werdenfelser and the old type German black-white cattle.