Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias

16 t h International Congress on Animal Reproduction
Poster Abstracts 211
but not all the parameters; the magnitude of the changes in the sperm
kinematic parameters was quite similar for each of the 8 bulls between
fresh and post-thaw semen. Immediatly after thawing, VCL and VAP
showed significant differences among the 8 bulls, however VSL was
no significantly different. Individual variation in semen freezability is
recognized to exists in bovine, and has been related with the incidence
of motile distinct sperm subpopulations in the fresh ejaculate, but
further results are needed to complete the Asturiana de la Montaña
genetic resource bank characterization.
This work was performed in collaboration with ASEAMO and
supported by RZ2004–00031–C02–01.
P555
Captive breeding strategies affect sperm traits in
Peromyscus leucopus
Martinez-Pastor, F 1 *; Malo, AF 2,3 ; Alaks, G 2 ; Lacy, RC 2
1National Wildlife Research Institute (IREC) (UCLM-CSIC-JCCM) and
Institute of Regional Development (IDR), University of Castilla-La Mancha,
Spain; 2 Chicago Zoological Society, Dept. of Conservation Science, 3300
Golf Road, Brookfield, IL 60513, USA; 3 Smithsonian Institution, Center for
Conservation and Evolutionary Genetics, National Zoological Park,
Washington D.C. 20008, USA
Captive breeding programs are the only option for many endangered
species. However, it is believed that inbreeding and genetic adaptation
to captivity may make the descendants from many captive programs
unsuitable for release back into the wild. Male fertility is one of the
traits potentially affected, so there is a need to known how captive
breeding programs affect sperm traits. We have measured the effects
of 10 generations of three different captive breeding strategies on
Peromyscus leucopus, originating from the same wild population: (1)
random mating (RAN), (2) minimizing the mean kinship (MK) of the
offspring (Species Survival Plan breeding strategy; SSP) and (3)
selecting for docility (DOC), by which more docile mice (behavioral
scores) are bred (mimicking the default breeding strategy in
captivity). Twenty males from each group were euthanized (CO 2 ).
Cauda epididymes were collected and put in a 0.5-mL drop of
modified Tyrode (300 mOsm/kg), covered with paraffin oil (37 °C),
and pierced. After 5 min, the medium was transferred to microtubes.
We evaluated the number of spermatozoa (Neubauer hemocytometer),
% of motility (light microscopy ×400) and viability (eosin/nigrosin
staining, ×400). Spermatozoa were challenged using an osmotic
resistance test (ORT): osmolality was raised to 500 mOsm/kg, and
after 5 min reverted to 300 mOsm/kg, assessing motility and viability
5 min later. The effect of the 3 groups on sperm traits was analyzed by
ANOVA and Tukey test (results as median and interquartile range).
RAN yielded significantly more spermatozoa (146.4×10 6 [113.3,
191.6]) than DOC (100.8×10 6 [80.3, 116.7]), SSP being in between
(138.2×10 6 [85.1, 176.6]). Motility (77.5% [68.8, 85]) and viability
(61% [53.8, 70.6]) were not different between groups. After ORT,
viability decreased (48% [38.9, 55]), but the change was not
significantly different among groups. However, motility was
significantly lower for DOC (27.5% [20, 36.3]) than for RAN (40%
[35, 42.5]) or SSP (42.5% [38.8, 55]). Overall, sperm numbers and
motility were reduced in the DOC group, announcing the negative
reproductive effects of not minimizing MK and suggesting the
absence of large differences between RAN and SSP. Our results
suggest that the breeding strategy affects sperm traits, and that
selecting the more docile individuals as breeders might pose a risk.
However, genetic drift might also be playing a role. Lastly, this study
might help with the setup of sperm banks for the conservation of
endangered species from this genus (e.g., Alabama beach mouse, P.
polionotus ammobates).
P556
Ovarian tissue cryopreservation in the doe rabbit: from
freezing to birth
Neto, V*; Joly, T; Salvetti, P; Lefranc, AC; Corrao, N; Guérin, P; Buff, S
Université de Lyon, Unité Cryobio - ENVL/ISARA Lyon, Ecole Nationale
Vétérinaire de Lyon, 1 avenue Bourgelat, 69280 Marcy l’Etoile
Introduction Ovarian tissue cryopreservation aims to preserve
simultaneously thousands of immature (primordial to primary stage)
follicles of the ovarian stock. It may allow preservation of the
reproductive potential of women who are at risk of becoming sterile
and may also contribute to preserve the animal genetic resources. The
objectives of this study in the doe rabbit were to determine the
influence of different freezing parameters and to propose a slow
freezing process for the cryopreservation of the ovarian tissue.
Methods A fractional experimental design was used to discriminate
5 freezing parameters. The nature (DMSO vs. 1,2-PROH) and the
concentration (1.5M vs. 2M) of the cryoprotectant, the nonpenetrating
cryoprotectant (sucrose or trehalose), the equilibration process (1 vs.
3 steps) and the post-seeding freezing rate (0.3 vs. 2°C/min) were
evaluated. The morphological analysis of the preantral follicles was
performed before (control) and after freezing. The best combination
of freezing parameters was finally challenged by orthotopic autograft
and in vivo resumption of folliculogenesis. Cryopreserved ovarian
fragment was grafted to the controlateral ovarian pedicle of
16 females. Then, females were inseminated along 9 months.
Results The experimental design showed that 1,2-PROH (p=0.08) and
trehalose (p=0.07) tended to improve the morphology of preantral
follicles submitted to freezing. The freezing rate seemed to have the
greatest impact on the follicular morphology which was improved by
the use of a freezing rate of 0.3°C/min (p