Effects of Taurine or Trehalose supplementation on functional competence of cryopreserved Karan Fries semen

Abstract

Cryopreserved semen is commonly used for assisted reproduction in livestock including cattle. However, spermatozoa undergo numerous physiological and biochemical changes during freezing and thawing process that affects their fertilizing ability. The aim of present study was to improve the post thaw quality of crossbreed cattle "Karan Fries" (Holstein-Friesian×Tharparkar) spermatozoa. A total of nine ejaculates from three randomly chosen Karan Fries bulls were extended and cryopreserved in Tris-egg yolk citrate (EYTC) extender supplemented with 50mM Taurine or 100mM Trehalose. Semen samples cryopreserved without these additives in EYTC extender were taken as a control. Cryopreserved semen were thawed and assessed for semen quality parameters like sperm motility, viability and plasma membrane integrity. Extent of capacitation was measured by estimating the number of sperm that underwent an acrosome reaction with Lysophosphatidyl choline (LPC) addition by dual staining with giemsa and trypan blue stains. Oxidative stress in terms of rate of H(2)O(2) production and membrane lipid peroxidation were assessed in spermatozoa. Intracellular calcium concentration was also measured using fluorescent dye Fura-2AM. Post-thaw semen evaluation showed that supplementation of Taurine or Trehalose to EYTC extender significantly (P<0.05) increased motility, viability and membrane integrity of spermatozoa. Percentage of cryocapacitated spermatozoa was also significantly (P<0.05) decreased in presence of these additives. Similarly, rate of H(2)O(2) production, lipid peroxidation and intracellular calcium were found to be significantly (P<0.05) higher in spermatozoa cryopreserved in absence of these additives. The results obtained clearly indicated that supplementation of Taurine or Trehalose to EYTC extender prior to cryopreservation improves Karan Fries sperm quality.