EFFECT OF ANTIOXIDANTS ON IN-VITRO MATURATION OF VITRIFIED BOVINE OOCYTES
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Date
2016-07
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Assam Agricultural University, Khanapara, Guwahati
Abstract
A total 717 ‘A+B’ grade oocytes were collected by aspiration cum slicing techniques from 294 numbers of cattle ovaries obtains from abattoir within 1-2 hours of slaughter. A total 651 ‘A+B’ grade immature oocytes were vitrified by two-step vitrification technique with combination of ethylene glycol and glycerol @ 7M concentration. Five hundred twenty eight numbers of normal vitrified-thawed bovine follicular oocytes were classified in to 8 experimental groups consisting of 66 numbers of oocytes in each and conducted in-vitro maturation as vitrified control (without antioxidant) and supplemented with different concentration of Vitamin E (50µM, 100µM, 200µM) and vitamin C (50µM, 100µM, 200µM) and combination of vitamin E (100µM) + vitamin C (100µM) groups. Non-vitrified 66 numbers of oocytes were used for in-vitro maturation in media without supplementation that served as control media.
The rate of cumulus cells expansion and polar body formation was significantly (P<0.01) higher in non-vitrified control (85.18 ±2.57 and 65.38±1.83, respectively)group than vitrified (51.67±1.94 and 30.26±0.16, respectively) control group of bovine follicular oocytes. The effect of addition of antioxidants viz. vitamin E and vitamin C in media at different concentrations (50µM, 100µM, 200µM) were studied separately. The rates of vitrified bovine follicular oocytes with cumulus cells expansion and polar body formation were 56.39±3.49, 69.95±3.20 and 54.44±4.73 per cent and 34.62±1.83, 56.23±1.61 and 31.62±4.50 per cent in medium supplemented with 50µM, 100µM and 200µM of vitamin E, respectively and 52.79±1.39, 71.19±2.63 and 51.17±3.59, per cent and 33.56±2.18, 54.57±1.69 and 30.43±2.01, per cent in medium supplemented with 50µM, 100µM and 200µM of vitamin C, respectively. The mean percentage of cumulus cells expansion and polar body formation was significantly (P<0.01) higher in media supplemented with 100µM of vitamin E or vitamin C group than 50µM and 200µM of vitamin E or vitamin C groups and vitrified (without antioxidant) control group of oocytes. The rate of cumulus cells expansion and polar body formation of vitrified bovine follicular oocytes was significantly (P<0.01) higher in group supplemented with combination of vitamin E + vitamin C @ 100µM of each (83.23±3.00 and 61.25±3.38, respectively) than vitrified control (51.67±1.94 and 30.26±0.16, respectively) group. While comparing the best concentration groups of all experimental groups, DMRT indicated that the mean percentage of cumulus cells expansion and polar body formation was significantly (P<0.01) higher in combination of vitamin E @100 µM + vitamin C @100 µM group and non-vitrified (control) group than vitamin E @100 µM, vitamin C @100 µM groups. Vitrified control group was significantly (P<0.01) lower than the other experimental groups.
The result of the present study showed that the rate of vitrified bovine follicular oocytes in respect of cumulus cells expansion and polar body formation was significantly (P<0.01) higher when antioxidants like vitamin E @ 100 µM or vitamin C @ 100 µM were added as compared to vitrified (without antioxidant) control. Each of vitamin E (100 µM) and vitamin C (100 µM) supplemented in TCM-199 improved the rate of in-vitro maturation of vitrified bovine follicular oocytes. Vitamin E@ 100µM + vitamin C@ 100µM supplemented in TCM-199 showed the highest rate of in-vitro maturation of vitrified bovine follicular oocytes.
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