Influência de sistemas de refrigeração sobre a qualidade do sêmen ovino criopreservado em palhetas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

This study aimed to evaluate the influence of different types of cooling systems upon the post-thawing quality of ram semen, through the measurement and comparison of cooling rates. The parameters were motility, vigor, morphology damages, viability and acrossomal state through the use of Trypan-blue/giemsa coloration, at the end of the 90 minutes of cooling and post-thawing. With regard to the analysis of post- thawed semen, the same parameters were used, in addition to the assessment of the integrity of the plasmatic membrane using de fluorescent stains propidium iodide (PI) and carboxifluorescein diacetate (CFDA), and the resistant test through incubation of semen at 37 C during 4 hours. The semen refrigeration was carried out in a domestic refrigerator and in a horizontal freezer. To control the fall of temperature of the two equipments, the straws were disposed between plastic bags containing water at 32C, creating four combinations of cooling procedure: RS (refrigerator without bag), RC (refrigerator with bag), BS (horizontal refrigerator without bag) and BC (horizontal refrigerator with bag). The different protocols resulted in four cooling rates: -1.4C/min, -0.4C/min, -2.9C/min and -0.45C/min, for RS, RC, BS and BC, respectively. At the end of cooling period, there was a significant difference among the treatments on the sperm motility (P<0.05), the BS treatment showed the lowest percentage of sperm motility (58.1%). The percentage of live spermatozoa with intact acrosome was different (P<0.05) among treatments, the BS treatment had the lower mean (85.3%). The percentage of dead spermatozoa with intact acrosome was different (P<0.05), the BS treatment had the highest mean (14.1%). There was a significant difference on the percentage of morphological defects at the end of cooling (P<0.05); the BS treatment had the highest mean (15.4%), the systems RC (11.5%) and BC (11.1%) resulted in the lower means and the RS (13.6%) was identical to others. To the other sperm parameters post-cooling, there were not differences. Regarding frozen-thawed semen, there were no parameters with differences. At the end of the resistant test period, there was no significant difference among the treatments. On basis of these results, it was concluded that the different cooling rates only affected ram semen at the end of cooling stage. The evaluation of frozen-thawed semen does not show any effect on the differents cooling protocols.

ASSUNTO(S)

cooling-rates ovino curvas de refrigeração ciencias agrarias frozen ovine thaw descongelação congelação

ACESSO AO ARTIGO

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