Abstract
A continuous decline in the number and range of capercaillie (Tetrao urogallus L.) in many European countries can be observed, mostly due to habitat destruction by human activity, unecological forestry management, and increased density of natural predators. Ex situ in vitro gene banks provide a unique opportunity to preserve the genetic material for future generations. Simple and effective cryopreservation methods for capercaillie semen are discussed. Semen was collected from seven males kept in the Capercaillie Breeding Centre at Forestry Wisła in Poland. Within five minutes after collection, ejaculates were diluted with EK diluent, then divided into two parts, and subjected to two freezing procedures: in pellets and in straws. In fresh semen, ejaculate clearness, viscosity, color and volume, as well as sperm concentration, motility and morphology, were evaluated, while in frozen-thawed semen only motility and morphology of sperm were determined. Fertilizing ability of thawed semen was examined for samples frozen in straws. Significant (P<0.05) differences between individual males were found in relation to the majority of fresh semen traits: ejaculate volume averaged 102.1 µL (varying from 49.0 to 205.0); average sperm concentration was 632.5 x106 mL-1 (178.8–1257.1); percentage of live normal cells varied from 39.2 to 70.3% (58.7% on an average); percentage of motile cells ranged from 76.0 to 85.7%) and motility parameters were male dependent, as well. Both cryopreservation methods had a negative effect on morphology and motility of frozen-thawed semen; however, the straw method yielded 60.7% and the pellet method 42.5% of live cells in total in thawed semen (P<0.05), while the number of live normal (intact) cells was similar (22.4 and 22.2%, respectively). Egg fertility varied between 77.8 and 91.7% (average 84.4%). Both freezing procedures seem to be effective in obtaining acceptable viability and high fertilizing potency of thawed sperm and can be used to create a gene bank of capercaillie semen.
Highlights
Semen preservation in domestic avian species is only rarely used in breeding practice, due mainly to economic reasons, despite its long-proven value for the optimization of male genetic potential [1], [2]
Ex situ in vitro gene banks provide a unique opportunity to preserve the genetic material for future generations
Significant (P
Summary
Semen preservation in domestic avian species is only rarely used in breeding practice, due mainly to economic reasons, despite its long-proven value for the optimization of male genetic potential [1], [2]. Cryopreservation of Capercaillie Semen of reproductive cells for the ex situ management of genetic diversity in birds [3]. Biotechnological methods used in poultry reproduction, such as artificial insemination (AI) or semen cryopreservation, are adopted for a variety of free-living bird species, especially for endangered ones [4], [5]. An increase in reproductive efficiency of capercaillies kept in a closed aviary system by the use of biotechnological methods contributes significantly to the achievement of this goal. Ex situ in vitro gene banks in the form of frozen semen provide a unique opportunity to preserve the genetic material and use it even after the death of the donor [6]. The use of AI in small populations, with diluted or cryopreserved semen, may allow preservation of biodiversity, without the need to transport the birds, which in such cases are exposed to severe stress [5]
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