Fertilizing ability of the cryopreserved cock sperm depeniding on cholesterol levels and cholesterol impact on the degree of damaging of the membrane structures in spermatozoa

One of the ways of preservation of the biological diversity in poultry and other farm animals is cryopreservation of reproductive cells. For poultry currently is already developed technology of spermatozoa, but percentage fertilization after thawing of individual ejaculates is on low level.During freezing and thawing spermatozoa can get both irreversible damages (losses of mobility and various morphological defects) and reversible damages (mainly temporary failures of the structure and penetration ability of membranes). Common parameters for selection of ejaculates for cryopreservation are: their volume, concentration and mobility of the spermatozoa. But these criteria do not reflect the whole degree of cryotolerance of the reproductive cells. This depends in wide extent on the condition of the membrane, because membranes are being firstly and mostly during the freezing and thawing process. There was found a positive correlation between spermatozoa mobility after thawing and degree of damaging of membrane structures during the freezing-thawing process. The coefficient of range correlation between the percentage of mobility and percentage of damaged spermatozoa was -0,49 (P < 0,01). In the article are presented results of the investigations of cryoresistance of cock sperm depending on lipid (cholesterol) in it. There are gained data of the cholesterol content in the native sperm with use of enzymatic colorimetric assay. The spermatozoa concentration was measured as mg/bln x 10-2. The parameters of the sperm membranes damaging were evaluated in de-frozen sperm with use of Sperm VitalStain colorant and microscopic visual system. There was found, that the sperm with cholesterol content on the level of ≤ М average had better cryoresistance compared to the sperm with high levels of cholesterol. This reflects in the lower damaging of the spermatozoa in freezing-thawing cycles (52,8% not damaged against 44,6%) in the experiment II ; better mobility after thawing (60,5% against 37,3% in the experiment and 65,9% against 63,2% in the experiment II); and, most important, better fertilizing ability (60,5 % against 36,0% in the experiment I and 78,4 % against 67,5% in the experiment II ).

Poultry breeding, artificial insemination, sperm, lipids, cholesterol, cryopreservation

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