Avaliação espermática do sêmen criopreservado de touros Curraleiro/Pé Duro em banco de germoplasma
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2012-02-28
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Universidade Federal de Goiás
Resumo
This investigation aimed to evaluate the quality of cryopreserved semen from 21
Curraleiro/Pé Duro bulls in germplasm bank, categorizing the doses of the sires
according to spermatic parameters that search the oocitary fertilization, and
verifying in vitro the fecundant potential of the seminal dose. All the samples were
thawed and analyzed by the spermatic exams of morphology, kinetics, integrity of
plasmatic membrane and integrity of acrosome; however, only four of them also
were evaluated through the fertilization rates, due to the major number of stocked
straws, which allowed to test more than one in vitro essay. Approximately 200
spermatozoids were counted for each exam, the results were expressed in
percentages and submitted to simple descriptive statistics (mean and standard
deviation), using as comparative reference, the patterns suggested by the
Brazilian Animal Reproduction College for bovine thawed semen, as well as
values obtained in other investigations. The results of the four spermatic exams
were verified, and were searched the most important parameters that aim the
fertility, being in the morphology the rate of normal spermatozoids (NRM) and
major defects (DMA); in the kinetics, the progressive motility (MP) and rapid cells
(RPD); in the integrity of plasmatic membrane, the whole plasmatic membrane
(MPI); and in the integrity of acrosome, the live spermatozoid with whole acrosome
(EVAI). From the 21 analyzed doses, ten presented adverse values in the
mentioned spermatic parameters, and of these samples, seven showed
divergences, because they had negative results for fertilization in some exams and
favorable results in others, revealing the complex nature of the spermatozoid.
Were taken into account for Pearson correlations, Cluster analysis and a
dendrogram elaboration, the parameters NRM, DMA, MP, RPD, MPI and EVAI.
The Cluster created by spermatic similarity three groups (G1, G2 e G3), for
morphology, kinetics, integrity of plasmatic membrane and integrity of acrosome.
The results were evaluated through simple descriptive statistics, and the difference
of means by Duncan and Kruskal Wallis tests, at 5% significance level. It is worth
mentioning that in the dendrogram the DT10 and DT19 were discriminated from
the groups for having very distant values from the rest of seminal doses. In
fecundation rates evaluation, three replicates were made with the straws of the
four chosen bulls, passing previously through Percoll gradient (45:90%), for
eliminating the defective cells and improving the fertilizing capacity. This selection
allowed favorable results, with rates of fertilized oocytes superior to 60%. In the
evaluation of masculine chromatin 18 hours post in vitro insemination high
Pronucleus rates were observed. The statistical difference of these values was
estimated by Chi-square test. The results revealed the spermatic quality and in
vitro fecundant capacity of Curraleiro/Pé Duro analyzed semen, enabling to
delineate appropriate strategies, for the conservation of this local genetic resource
in extinction, owner of unique characteristics of adaptation and rusticity, that could
be included hereafter in the brazilian cattle herds.
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MONTESINOS, Iván Salamanca. Spermatic evaluation of cryopreserved semen from curraleiro/ pé duro bulls in germplasm bank. 2012. 67 f. Dissertação (Mestrado em Ciências Agrárias - Veterinaria) - Universidade Federal de Goiás, Goiânia, 2012.