Use of native chicken breeds (Gallus gallus domesticus) for the development of suitable methods of Cantabrian capercaillie (Tetrao urogallus cantabricus) semen cryopreservation

Abstract

Background:The Cantabrian capercaillie (Tetrao urogallus cantabricus) is critically endangered. This subspecies has the lowest genetic variability and it is in regression. It belongs to Phasianidae family; therefore, the domestic chicken (Gallus gallus domesticus) could be a good model for developing reproductive technologies for use in capercaillie populations with low availability of animals.Objectives: In this study, we analyzed the response of capercaillie sperm to the freezing-thawing process for contributing to the development of a semen cryobank of Cantabrian capercaillie. Methods:We used domestic chicken as the animal model in order to obtain the freezing protocol before applying on capercaillie. In the first experiment, two different extenders (EK and LR84) and different concentrations [4% and 6% dimethyl-acetamide (DMA) v:v] of cryoprotectants were evaluated using in-straw freezing method in domestic chickens. A pilot study in capercaillie males, using the same conditions evaluated in chicken, was performed. Results:In chicken, we found that the LR84-4% DMA media provided the best results for freezing semen. In capercaillie study, LR84 extender seemed to be the most appropriate diluent and 4% was the better dose of DMA cryoprotectant agent. Further, based on previous studies carried out in rooster samples, we also tested the glycerol (8% v/v) as a cryoprotectant for capercaillie semen cryopreservation. Conclusions:Our results suggest that sperm from both domestic and wild species had a similar response to freezing-thawing processes. Mediterranean chickens may be used as a suitable model for developing sperm freezing protocols that can be extrapolated to threatened capercaillie populations. In addition, LR84 media with glycerol was the most efficient extender to freeze capercaillie sperm native.

The In Vitro Evaluation of Rooster Semen Pellets Frozen with Dimethylacetamide

“…The current study showed that the 3% DMA group exhibits significantly (p < 0.05) higher proportions of TMOT and PROG motility compared to the 6% and 9% DMA groups. This result is supported by previous research which reported higher sperm motility at 3% DMA than the other treatments in local Egyptian strains (Dokki-4 and El-salam) [31] and Mediterranean chicken breeds [7], as well as in the Birchen Leonesa breed and wild birds [32]. Abouelezz et al [7] reported that the native Mediterranean chicken sperm is sensitive to DMA, and concentrations lower than 6% are recommended, while O'Brien et al [32] stated that the EK media improved the cryopreservation results with 4% DMA levels compared to the lower levels.…”

“…This result is supported by previous research which reported higher sperm motility at 3% DMA than the other treatments in local Egyptian strains (Dokki-4 and El-salam) [31] and Mediterranean chicken breeds [7], as well as in the Birchen Leonesa breed and wild birds [32]. Abouelezz et al [7] reported that the native Mediterranean chicken sperm is sensitive to DMA, and concentrations lower than 6% are recommended, while O'Brien et al [32] stated that the EK media improved the cryopreservation results with 4% DMA levels compared to the lower levels. On the other hand, DMA addition at the concentration of 6% can retain sperm motility and fertility after cryopreservation in chicken [33], 8% DMA in turkey [34], and red jungle fowl [6].…”

“…They indicated that the lower concentration of DMA at 3% improved the viability results compared to the high concentration. However, previous studies showed that the highest sperm viability was recorded in the 6% DMA group [32,35]. Castillo et al [29] documented the absence DMA concentration effect on the viability, whereas Annelisse et al [35] reported that the highest viability was recorded with 6% DMA.…”