INFLUENCE OF DEXAMETHASONE AND EPIDERMAL GROWTH FACTOR SUPPLEMENTATION IN SYNTHETIC OVIDUCTAL FLUID MEDIUM ON IN VITRO BOVINE EMBRYO DEVELOPMENT
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Date
2019
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
The study was designed to assess the individual and combined effect of
dexamethasone and epidermal growth factor (EGF) on in vitro bovine embryo
development. Ovaries of abattoir origin from crossbred cattle of Kerala were
subjected to study. All visible follicles of size 2-8 mm were aspirated and culture
grade oocytes were subjected to IVM in TCM-199 medium and fertilized in fertTALP medium and embryos were cultured in mSOF. Presumptive zygotes in group I
(n= 162) were treated with 0.1µg/ml of dexamethasone; Group II (n= 198) with
5ng/ml of EGF; Group III (n=199) with 0.1µg/ml of dexamethasone and 5 ng/ml of
EGF and Group IV (n= 154) kept as control. Embryo developmental competence was
assessed every 48 h and morphological evaluation and embryo viability (Hoechst
33342 staining) was performed on day 8. On day 2 significantly higher (p ≤ 0.05)
fertilization and cleavage rate was observed in group II (53.04 ± 2.87 and 35.69 ±
1.02 %) and group III (50.34 ± 2.18 and 34.47 ± 1.98 %) compared to group I (36.33
± 4.15 and 20.05 ± 3.46%) and group IV (33.00 ± 4.38 and 16.29 ± 4.64 %). On day
4 significantly higher 4 and 16 cell stage embryo was obtained in group II and group
III than group I and IV. A significantly higher (p≤0.05) 8 cell stage embryo was
observed in group III when compared to group I and IV. However there was no
significant difference in 8 cell stage embryo was observed between group II and III.
On day 6 and 8 morula/ blastocyst yield was significantly higher (p ≤ 0.05) in group II
and III (9.06 ± 0.89 and 8.21 ± 2.21) than in Group I and IV (3.63 ± 1.29 and 2.66 ±
1.54). The proportion of good and fair quality embryos were recorded on day 6, group
I (75 and 12.5%), II (52.6 and 31.6%), III (77.8 and 5.6%) and IV (28.6 and 57.1%).
Higher per cent of morphologically good and fair quality embryos on day 8 were
observed in group I (50 and 25%) and III (44.4 and 27.8%) than group II (10.5 and
15.7%) and IV (14.3 and 14.3%). Embryo viability assessed by Hoechst 33342 on day
8 revealed a higher per cent of viable embryos in group I and III (83.33 and 83.33%)
when compared to group II and IV (50 and 16.67%). The present study revealed that
supplementation of dexamethasone in mSOF improved the quality of embryos. The
supplementation of EGF in mSOF improved the yield of embryos and combining
dexamethasone and EGF in mSOF resulted in increased number of embryos with
better quality.