Coleta e criopreservação do sêmen de rã-touro, Lithobastes catesbeianus (Shaw, 1802)

• Autor(a) principal: Calado, Leonardo Luiz
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2221
• topic: Indução hormonal; Criopreservação seminal; Motilidade; Rã-touro; Hormonal induction; Sperm cryopreservation; Motility; Bullfrog; CNPQ::CIENCIAS BIOLOGICAS::ZOOLOGIA::ZOOLOGIA APLICADA::CONSERVACAO DAS ESPECIES ANIMAIS

The impact caused by alien species in Brazil and over the world presents consequences for native populations of frogs. The development of methodologies to preserve the native species and optimize the food production is a challenging task for aquaculture. The aim of the present study was to develop a protocol of induced spermiation in the bullfrog Lithobastes catesbeianus followed by sperm cryopreservation. Three experiments were conducted at Universidade Federal de Lavras and Universidade Federal de Viçosa, Minas Gerais State. The first experiment aimed to evaluate the induced spermiation using carp crude pituitary gland (CPE &#8211; 5000 &#8211; &#956;g/kg), buserelin acetate (BA &#8211; 13 &#956;g/kg), gonadorelin acetate (GA &#8211; 83 &#956;g/kg), and human chorionic gonadotropin (hCG &#8211; 830 IU/kg). Thirty males were induced with the mentioned hormones followed by sperm sampling hours afterwards. Sperm parameters (sperm motility, volume, color, vigor, odor, concentration) were compared in order to obtain the best hormone inducer. In the experiment 2, we aimed to evaluate the influence of the period after inducement on sperm traits. Another group of males (n=30) were induced using the best procedure obtained above and then the sperm was sampled at 2, 4, 6, 8, 10 and 12 hours afterwards. In the experiment 3, we have evaluated the toxicity and cryopreservation success using cryo-solutions composed by DMSO (at 1,0; 2,5; 5,0 and 7,5%) and methanol (at 1,0; 2,5; 5,0 e 7,5%) as the main cryoprotectants; and BTS at 1 or 5%. Sperm was diluted using the cryo-solutions and then observed the motility parameters (sperm motility, VIGOR and duration; n=11). The sperm was also cryopreserved using the same cryo-solutions and cooled in vapour nitrogen vessel (dry-shipper), and then observed the post-thawed sperm parameters. Data were compared by Kruskal-Walis test and Anova followed by regression analysis (P<0.05). Our results indicate that only AG and AB succeed to induce spermiation, where 100% and 20% of the males released the sperm, respectively. The period after inducement have influenced the sperm parameters of volume (y = 0,9727 + 01327x; R2 = 0,50) and concentration (y = -0,1784x + 2,5878; R2 = 0,86), although there was not a significant effect for other parameters. Regarding the toxicity of the cryoprotectants, the sperm motility did not show a significant effect with methanol (92,1 ± 8,0%) or DMSO (89,0 ± 3,0%), although sperm vigor (4,2 ± 0,1 and 3,6 ± 0,5) and the duration of motility (287 ± 14 10s and 252 ± 23s, respectively) showed a significant effect. A clear interaction was observed on motility parameters when methanol at 1% was associated with BTS at 5% and lactose at 1%. Similar trend was observed when DMSO or methanol was associated with lactose or BTS. Data regarding the post-thawed motility indicate that none of the cryosolutions succeed in maintain the sperm motility. In conclusion, the sperm sampling was optimized using gonadorelin acetate followed by sperm sampling 10 hour afterwards. Other investigations are stil necessary in order to improve the cryopreservation success.