In Italy, 53 local chicken breeds were described; the majority (67%) were classified as extinct and 21% at risk of extinction. Therefore, attempts for conservation of Italian avian breeds are urgently required. Sperm cryopreservation is a powerful tool to implement the ex situ in vitro conservation technique in bird populations at risk. The aim of this study was to assess the vari-ability in semen freezability between birds within the Italian endangered Bianca di Saluzzo (BS) poultry breed, in order to develop a conservation programme. BS (n = 18) roosters were housed at the Poultry Unit, Animal Production Centre, University of Milan (Lodi, Italy). After a semen collection training period, semen donors were selected and semen doses frozen in liquid nitrogen. Each day of collection, quantitative (volume, concen-tration) and qualitative (viability, total motility (TM), progressive motility (PM), kinetic parameters) sperm parameters were mea-sured. Semen was diluted to 1 × 109 sperm/mL with Lake pre-freez-ing medium containing 2% N-methylacetamide, loaded into 0.25 mL French straws, frozen for 10 min over a nitrogen bath at 3 cm of height and stored in liquid nitrogen at −196 ° C in cryo-genic tank. The straws were thawed at 5 °C for 100 s and sperm parameters were assessed. A total of 10 laying hens per selected male donors were inseminated twice to assess in vivo fertility and embryo viability. The mean volume and sperm concentration recorded in fresh ejaculates were 0.327 ± 0.17 mL and 3.303 ± 1.27 × 109 sperm/mL. Semen quality of fresh samples was significantly different among birds and only 6 were selected as donors. Furthermore, according to availability of semen doses, 3 birds (BS1, BS2, BS3) were used for artificial insemination trial. Higher values in PM and TM were found in BS2 (PM 25%, TM 98%) and BS3 (PM 33%, TM 98%) compared to BS1 (PM 18%, TM 81%) ejaculates. As expected, a general significant decrease in sperm quality occurred after the freezing-thawing process. Fertility and embryo viability were 30.6% and 95% in BS2, 7.5% and 66.7% in BS1, 8.45 and 57% in BS3. High individual variability was found in semen freezability, not always related to fresh sperm quality. In vitro quality of thawed semen was associated to the results obtained in the artificial insemination test. However, furthered analyzes must be performed to confirm the pres-ent results and to identify quality sperm markers for the selection of the best semen donors in conservation programs.
Variability in semen freezability within an Italian chicken breed
Michele Di Iorio;Nicolaia Iaffaldano;
2023-01-01
Abstract
In Italy, 53 local chicken breeds were described; the majority (67%) were classified as extinct and 21% at risk of extinction. Therefore, attempts for conservation of Italian avian breeds are urgently required. Sperm cryopreservation is a powerful tool to implement the ex situ in vitro conservation technique in bird populations at risk. The aim of this study was to assess the vari-ability in semen freezability between birds within the Italian endangered Bianca di Saluzzo (BS) poultry breed, in order to develop a conservation programme. BS (n = 18) roosters were housed at the Poultry Unit, Animal Production Centre, University of Milan (Lodi, Italy). After a semen collection training period, semen donors were selected and semen doses frozen in liquid nitrogen. Each day of collection, quantitative (volume, concen-tration) and qualitative (viability, total motility (TM), progressive motility (PM), kinetic parameters) sperm parameters were mea-sured. Semen was diluted to 1 × 109 sperm/mL with Lake pre-freez-ing medium containing 2% N-methylacetamide, loaded into 0.25 mL French straws, frozen for 10 min over a nitrogen bath at 3 cm of height and stored in liquid nitrogen at −196 ° C in cryo-genic tank. The straws were thawed at 5 °C for 100 s and sperm parameters were assessed. A total of 10 laying hens per selected male donors were inseminated twice to assess in vivo fertility and embryo viability. The mean volume and sperm concentration recorded in fresh ejaculates were 0.327 ± 0.17 mL and 3.303 ± 1.27 × 109 sperm/mL. Semen quality of fresh samples was significantly different among birds and only 6 were selected as donors. Furthermore, according to availability of semen doses, 3 birds (BS1, BS2, BS3) were used for artificial insemination trial. Higher values in PM and TM were found in BS2 (PM 25%, TM 98%) and BS3 (PM 33%, TM 98%) compared to BS1 (PM 18%, TM 81%) ejaculates. As expected, a general significant decrease in sperm quality occurred after the freezing-thawing process. Fertility and embryo viability were 30.6% and 95% in BS2, 7.5% and 66.7% in BS1, 8.45 and 57% in BS3. High individual variability was found in semen freezability, not always related to fresh sperm quality. In vitro quality of thawed semen was associated to the results obtained in the artificial insemination test. However, furthered analyzes must be performed to confirm the pres-ent results and to identify quality sperm markers for the selection of the best semen donors in conservation programs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
