Effect of supplementation of the middle and freezing with vitamin "E" about: the feasibility and quality of frozen bovine semen

Abstract Text: The conditions of storing semen induce the formation of free radicals from the oxidation of fatty acids components of the plasma membrane. Those effects are related with the aggression on the plasma membrane and other cellular organelles, caused by oxidative stress, heat shock and formation of intracellular ice crystals. The interception of reactive oxygen species is based in breaking the chain reaction that occurs with free radicals to form oxidation products. This breakdown promoted by certain antioxidants, for example, α-tocopherol (Vitamin E), radicals must not result in final products that is, without electrostatic despareado. This work had as purpose appraise the quality and the feasibility of frozen semen in medium supplemented with vitamin “E”. Semen collections of 16 bulls Brangus race of reproductive age, with proven fertility and healthy were performed. The semen was collected by eletroejaculation method, isolated shock heat, light and previously heated. Immediately after collection each ejaculate obtained was divided into two fractions where each fraction was diluted in one of two treatments being: T1-control (medium without supplementation), T2-medium supplemented with 2.0 mmol / L of vitamin "E". The basic medium used for freezing was tris-yolk sodium citrate and the methodology used was described by Beconi et al. (1991). The semen was stored in straws of 0.25 and maintained in nitrogen until the time of analysis. For evaluation of sperm viability it was used the method for staining with eosin associated negrosina in thawed semen, cells with membrane lesions present in the nucleus stained by eosin, remaining reddish, the living cells, colorless microscopic reading. In force and motility parameters did not differ between treatments. On sperm viability (eosin / negrosina) had a significant difference between treatments (p = 0.0031), where treatment control was superior to treatment with Vitamin "E", indicating that the inclusion of 2.0 mmol / L was deleterious to sperm viability. More studies should be conducted to find an optimal concentration to ensure a better sperm viability after thawing semen.

Keywords: anti-oxidant; frozen semen.