Abstract
Cryopreservation induces sub lethal damage to the spermatozoa, thereby reduce their fertile life. There are some biochemical additives that may enhance buffalo semen freezability; L-carnitine is one of these biochemical semen additives. Till now, the exact effects of L-carnitine on buffalo semen processing outcomes haven’t been discovered. The current study aimed to clarify L-carnitine roles during buffalo semen cryopreservation. Semen was cryopreserved in tris-based extender supplemented with different concentrations of L- carnitine (0.01, 0.05 and 0.1mg/ml)Vs.Tris-based extender only (control). Then they were processed to cryopreservation and thawing to assess different semen characteristics. Cryopreserved semen was assessed for percentage post- thawing motility, acrosomal and plasma membrane integrity, viability, DNA damage, antioxidant enzymes concentration, lipid peroxidation, in vitro fertilizing potentials and conception rate. Current results indicated that addition of 0.05 mg/ml L- carnitine to semen extender significantly (P<0.05) improved post-thawing motility, viability and acrosomal integrity (63.33±9.28 %, 133.33±9.40 and 12.33± 2.02 %, respectively) compared with control (43.33±6.01 %, 74.16± 10.93 and 24.67±2.03 %, respectively). Moreover, 0.05mg/ml L- carnitine significantly increased (P<0.05) total antioxidant capacity (TAC), superoxide dismutase (SOD) and glutathione peroxidase (GPx) concentrations (0.50±0.07 mµ/ml, 73.67±5.37 U/ml and 106.66±12.03 U/L, respectively) with respect to the control (0.19±0.01 mµ/ml, 27.33±3.49 U/ml and52.33±4.09 U/L, respectively). Furthermore, 0.05mg/ml L- carnitine significantly decreased (P<0.05) lipid peroxidation of the cryopreserved spermatozoa compared with the control semen (11.00±1.73 vs 24.82±4.90nmol/ml). Likewise, at this concentration sperm DNA damage, tail length and tail moment of the cryopreserved semen significantly (P<0.05) reduced (1.87±0.36 %, 1.83±0.33 µm and 3.72±1.44, respectively) compared with control (3.47±0.13 %, 3.48±0.17 µm and 11.91±0.87, respectively). Additionally, 0.05 mg/ml L- carnitine significantly (P<0.05) improved in vitro fertilization rate (57.45%) and conception rate (61.76%) compared with the control (33.33 and 37.93%, respectively). In conclusion the use of 0.05 mg/ml L-carnitine in the freezing extender improves DNA integrity through enhancing the antioxidant defense of buffalo sperm cells and decreasing the rate of lipid peroxidation. Therefore, L-carnitine may improve sperm cryopreservation quality, reduce cryodamage and improve sperm fertilizing potential
Highlights
Infertility and reduced fertility are one of the major problems in veterinary practices especially for valuable animals
L-carnitine is a well-known cellular antioxidant, but there is a paucity of exploration about its protective role during buffalo semen cryopreservation
These results are in agreement with Lenzi et al (2003) and Agarwal and Said (2004) who reported that L-carnitine can improve sperm motility and viability
Summary
Infertility and reduced fertility are one of the major problems in veterinary practices especially for valuable animals. Male infertility represented about 30% to 50% of infertility cases (Aliabadiet al., 2013). Semen cryopreservation is one of the most effective and acceptable methods to maintain male fertility potential. Long-term sperm storage, sperm banking and the possibility of storing the sperm of proven bull are the main objectives of using cryopreservation method. Despite many advantages of sperm cryopreservation, this methodentries some hazardous that reduces sperm fertilizing capacity through morphological damage, DNA damage and generally impaired sperm motility and viability (Singer et al, 1980). Several researchers found that cryopreservation decreases sperm motility parameters, normal morphology and increases
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