Relação da fertilidade de sêmen bovino congelado com testes de avaliação espermática in vitro

• Autor(a) principal: Siqueira, Jeanne Broch
• Data de Publicação: 2004
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5034
• topic: Bovino; Sêmen; Fertilidade; Criopreservação; Bovine; Semen; Fertility; Cryopreservation; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::REPRODUCAO ANIMAL

The objective of this study was evaluate the relationship between complementary tests (hypoosmotic swelling test - HOST, thermo resistance test - TRT, and acrossome reaction test AR test) with the conventional evaluation tests (physical and morphologic aspects) of bovine frozen/thawed semen, the values were correlated with the conception rate. Twenty-three frozen specimens from 13 Nelore bulls were used. The semen was collected and diluted in standard egg yolk, packing in 0,25mL straws with concentration of 25 x 106 viable spermatozoa per by pallet. The physical evaluation of the semen was constituted of post-thawed spermatic motility and vigour. The spermatic defects were classified in major, minor and total defects. For HOST, 20 mL of frozen/thawed semen, was added to 1,0 mL of a fructose solution in the concentration of 100mOsm/L previously heated to 37ºC, later on incubation for one hour. TRT consisted of submitting the post-thawed semen specimens to the incubation in water bath at 37ºC for 3 hours (T0: 0 hour; T1: 60 minute; T2: 120 minute; T3: 180 minute), being evaluated spermatic motility and vigour at each time (T). For the AR test the technique of naphthol yellow and erithrosin B was used to identify the percentage of spermatozoa with acrossome reacted after the frozen/thawed. To check the correlations between HOST, TRT and AR test with spermatic motility and pregnancy rate comparisons inside each bull and among different bulls were done by Qui-square at a significance rate of 5%. Analysis of regression logistics was made to evaluating the fixed effects as: effect of the bull, frozen semen specimens, retreat, reproductive status and inseminators. The average values for the spermatic motility of frozen/thawed semen evaluated by TRT were of 53.48% (T0), 43.69% (T1), 35.88% (T2), and 33.04% (T3). The percentage of reactive cells found in HOST was 37.89%. Positive correlation of average intensity were found for spermatic motility postthawed and the HOST (0,21). Weak and positive correlation of the T3 motility with HOST was high (0.64), demonstrating that the spermatozoa maintained the functionality of its plasmatic membrane after the cryopreservation, stayed viable for more time. The percentage of cells that presented acrossome reaction post-thawed was 9.85%. Negative correlations of average and high intensity (-0.25 and 0.46, respectively) were found for acrossome reaction test and the spermatic motility post-thawed and after 3 hours of incubation. No correlation (p>0,05) of TRT, HOST, AR test and post-thawed motility with the conception rate was found. There was any parameter which considered separately, could evaluate the fertilizer capacity of the semen, since the spermatic viability is multifatorial question associated with the characteristics of structural and functional integrity of their components. No significant correlation (p>0,05) of TRT, HOST, AR test and post-thawed motility with the pregnancy rate was found. The characteristics analysed may not be considered alone to evaluate the fertilizing capacity of the frozen/thawed semen.