Freezability of semen collected from ganders of 12 breeds covered by the Polish genetic resources conservation program

A rapid decline in wild animal biodiversity, as well as in the number of local livestock breeds of lower economical values, makes species and breeds protection and creation of genetic reserves a necessity and a challenge of the 21st century. For birds, semen freezing is still the best method of gene preservation ex situ in vitro. The aim of the presented study was to assess the susceptibility to freezing process and to establish the semen gene bank of twelve goose breeds covered by the Polish genetic resources conservation program. Sexually mature ganders were randomly selected from four northern local breeds: Kartuska, Pomorska, Rypinska, Suwalska, four southern local breeds: Garbonosa, Kielecka, Lubelska, Podkarpacka and four foreign goose breeds: Kuban, Landes, Roman and Slovakia. Each breed was represented by 12 males, twelve repetitions were carried out. Semen samples were frozen in a computer-controlled cryogenic chamber using a method developed for White Koluda goose. The basic evaluation criterion was sperm morphology in fresh and freeze-thawed semen assessed in nigrosine-eosin stained histological smears. The percentage of live in total and live normal sperm in the fresh semen differed significantly (P<0.05) between breeds. Semen of Kartuska and Suwalska ganders (northern breeds), contained the highest percent of live sperm - 94.4 and 94.1 respectively, including 52.5% and 54.2% of live normal sperm, while the lowest number of these forms were observed for Slovakia goose - 86.4% and 29.2%, respectively. The freezing process resulted in a significant (P<0.05) reduction in the total number of live and live normal sperm and an increase in dead sperm in all groups. Cryopreservation process was the most effective in case of Suwalska goose semen (28.4% of live normal cells in thawed semen) and the less profitable for Landes (7.4% of live normal cells). The analyzes showed significant differences between breeds in sperm morphology in fresh and thawed semen. Moreover, the high proportion of live spermatozoa in the fresh semen did not guarantee a high proportion of spermatozoa after thawing, indicating the differences in semen susceptibility to cryopreservation process depending on goose breed.