The impact of high temperature on the development and quality of in vitro matured beef cattle oocytes and their potential to subsequent embryonic development

Abstract

The study aimed to evaluate the effect of high temperature on cattle oocytes matured in vitro at 39, 41, 42, 43˚C and to evaluate apoptosis through Caspase-activity and DNA fragmentation on produced embryos. Cumulus oocyte complexes (COC) were matured at 39, 41, 42 and 43˚C. Two best maturation temperatures were selected for maturation throughout embryo production. Post maturation, matured oocytes were exposed to standard embryonic conditions. Embryos were evaluated at 3 stages: ≥ 2-4 cell, ≥ 8cell and blastocyst to determine Caspase-3 activity and DNA fragmentation. Maturation of oocytes at 41 and 39˚C demonstrated no significant difference (p>0.05) however, higher maturation rate compared to 42 and 43˚C. Matured oocytes at 39 and 41˚C showed no difference (p>0.05) in embryo development. Blastocysts at 39˚C maturation had higher (p<0.05) nuclei cells compared to those at 41˚C. Caspase-3 activity was comparable at ≥ 2-4 cell and ≥ 8cell for both 39 and 41˚C maturation temperatures, however, 41˚C showed high DNA fragmentation compared to 39˚C maturation group. Blastocyst from oocytes matured at 41˚C had higher Caspase-3 activity and DNA fragmentation than those at 39˚C. Embryos derived from 41˚C maturation temperature resulted in evidence of apoptosis compared to 39˚C.