Effect of the addition of glycerol in different stages of the cooling on the freezability of stallion semen / Efeito da adição de glicerol em diferentes etapas do resfriamento sobre a congelabilidade do sêmen de garanhões

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of the present study was to evaluate the effect on the freezability of equine semen with the addition of glycerol in 0, 35 and 60 minutes the cooling period. Semen from two adult stallions (Mangalarga Marchador) were used, totalizing 11 colections of semen. The evaluation consisted of sperm progressive straight motility, total motility, sperm vigor, live/death cells (supravital), functional integrity of sperm plasma membrane (Hyposmotic Swelling test - Host) and sperm morphology analyses in the semen in natura, before and after freezing the semen. Each collected semen was divided in three treatments. T1: addition of the cryoprotector occurred before the cooling; T2: addition occurred after 35 minutes of the cooling; T3: the addition occurred immediately before the freezing, to the 60 minutes of cooling. After the minimum frozen period of 12 days, the semen samples had been thawed at 75 C per 7 seconds. The thawed samples had remained for 120 minutes at 38 C for longevity evaluation. Differences (P <0.05) among the animals used in the experiment, were noted in sperm morphology. One of the stallions showed average values of abnormal sperms bellow of the praised standards. No relations (P >0.05) were registered among average values of the morphology test, supravital test and Host in semen in natura. The supravital test showed relation (P <0.05) only with the sperm vigor in the analysis of the semen in natura. No differences (P >0.05) were registered among physical analyses, in the Host, supravital test, the morphologic analysis and in the evaluation of longevity in the frozen/thaw semen of three considered protocols. These results suggest that the time of balance between the semen and glycerol does not affect the quality and the longevity of the semen. Seminal qualities had been considered impracticable in fertility terms, after 60 minutes of incubation on longevity test. The supravital test of the frozen/thawed semen showed relation with the progressive sperm motility (r = 0.81) and sperm vigor (r = 0.64) in the 3 considered trataments. The values of the Host used in this experiment were satisfactory due the large reaction of the spermatozoa when in contact with the hyposmotic solutions, however this test did not show relations (P >0.05) with the sperm physical parameters. The physical parameters of the semen before cooling did not present relation (P >0.05) with the physical parameters and with supravital test of frozen/thaw sperm. The no significant relations among the different tests used in this study, suggests that the information of these tests are used under different aspects, ratifying the complementary character of the same ones.

ASSUNTO(S)

cryopreservation criopreservação semen reproducao animal equine equino sêmen

ACESSO AO ARTIGO

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