Ejaculate collection efficiency and post-thaw semen quality in wild-caught Griffon vultures from the Sardinian population

Manuela Madeddu,Valentina Satta,Ciriaco Carru,Massimo Ledda,Andrea Rotta,Sara Succu,Giovanni G Leoni,Valeria Pasciu,Marco Muzzeddu,Salvatore Naitana,Angelo Zinellu,Fiammetta Berlinguer

doi:10.1186/1477-7827-7-18

Manuela Madeddu, Valentina Satta + Show 10 more

Open Access

https://doi.org/10.1186/1477-7827-7-18

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Abstract

This study aimed to test the feasibility of a programme of semen collection and cryopreservation in Griffon vultures. Four wild-caught individuals kept in captivity because of unrecoverable traumas were used. Semen collection attempts were made twice a week during three consecutive reproductive seasons (December – March) using the abdominal massage method. Ejaculation was successfully induced between late January and late February. Semen collection efficiency was rather low (27.9%) and it did not vary among individuals (p > 0.05). No differences were found in ejaculate volumes (12.5 +/- 9.1 μl), spermatozoa concentration (28.4 +/- 30.9 million cells/ml) and viability (61.3 +/- 13.9%) among the 4 vultures. ATP values differed among the four vultures (p < 0.001); B showed higher nucleotide concentration than both C and D, while it did not differ form A, whose values were higher compared with D. After freezing and thawing, semen in vitro viability, DNA integrity and ATP intracellular concentration were determined. Spermatozoa viability after thawing did not differ among the four individuals (52.6 +/- 5.8 in A, 53.4 +/- 4.6 in B, 50.4 +/- 3.2 in C, 42.5 +/- 2.7 in D), but it decreased significantly compared to fresh semen (p < 0.05). During 4 hrs in vitro culture, spermatozoa collected from B maintained over time a higher viability in vitro when compared to A, C and D. As evaluated by the comet assay method, DNA fragmentation after freezing and thawing did not differ in the 4 vultures. ATP concentration in frozen/thawed semen was significantly lower than in fresh semen (p < 0.0001). This study indicates that semen cryopreservation can be considered as a useful tool in the conservation of Griffon vulture genetic resources, but further studies are needed to optimize this technique.

Highlights

Establishing a genome resource bank, along with assisted breeding techniques, has the potential to preserve genetic diversity of many endangered species managed ex situ [1]
We have reported the potential application of semen cryopreservation in a program of gamete and embryo banking, designed to restore genetic diversity in small and isolated populations of wild ruminants, such as the European mouflon (Ovis gmelini musimon) and endangered gazelle (Gazella dama mhorr), through both in vivo and in vitro reproductive techniques [3,4,5]
It is noteworthy that researchers have promptly responded to the well known catastrophic collapse in the population of the Indian white-backed vulture (Gyps bengalensis) by studying its basic spermatology and developing a protocol for semen cryopreservation in order to conserve the specie through captive breeding and assisted reproduction [13]

Summary

Introduction

Establishing a genome resource bank, along with assisted breeding techniques, has the potential to preserve genetic diversity of many endangered species managed ex situ [1]. We have reported the potential application of semen cryopreservation in a program of gamete and embryo banking, designed to restore genetic diversity in small and isolated populations of wild ruminants, such as the European mouflon (Ovis gmelini musimon) and endangered gazelle (Gazella dama mhorr), through both in vivo and in vitro reproductive techniques [3,4,5]. The most feasible method for ex situ management of genetic resources in birds is semen cryopreservation. The feasibility of the construction and utilization of an avian semen cryobank for the ex situ management of endangered pheasants and of rare domestic lines and breeds of the species Gallus gallus has recently been reported [7,8]. It is noteworthy that researchers have promptly responded to the well known catastrophic collapse in the population of the Indian white-backed vulture (Gyps bengalensis) by studying its basic spermatology and developing a protocol for semen cryopreservation in order to conserve the specie through captive breeding and assisted reproduction [13]

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