Utilization of Post-Mortem Oocytes for In Vitro Embryo Production for Preservation of Adapted High Genetic Value Germplasm of Jersey Cattle

ABSTRACT: Assisted reproductive techniques offer a valuable tool for rescuing deceased germplasm for the establishment of replacement stock as well as conservation of valuable/threatened germplasm. The techniques assume greater importance for the preservation of the adapted dairy germplasm raised through decades of up-gradation using exotic semen, especially in the ecologically sensitive Himalayan region. Gamete retrieval from deceased animals is of special importance in countries where cattle slaughter is prohibited, thus rendering the abattoir-derived gonad availability impossible. The present study envisages the developmental competence of oocytes retrieved from dead Jersey cows. From 112 ovaries, derived from 56 deceased cows, 847 COCs were recovered and grouped by post-mortem interval (PMI): 0–6 h (Group I) versus 6–12 h (Group II). The proportion of Grade A & B oocytes did not differ significantly between the groups (65.4% vs. 59.0%). In vitro maturation (IVM) was significantly higher in group I (80.6 ± 2.0%) than in group II (46.2 ± 2.7%; p < 0.0001). With unsexed semen, cleavage was higher in Group I than Group II (55.7 ± 5.9% vs. 38.3 ± 7.9%; p = 0.012); while blastocyst yield showed only a non-significant trend in favour of Group I. Sex-sorted semen reduced cleavage and blastocyst rates overall, with no significant difference between groups. On days 7–8, 44 blastocysts from Group I and 2 from Group II were vitrified. Survival after thawing was 90.9% (40/44) and 100% (2/2), respectively. The results demonstrated that post-mortem ovaries from naturally deceased Jersey cows can supply developmentally competent oocytes suitable for IVEP, though demanding further technical refinements to be at par with the results obtained from oocyte retrieval from live animals using the OPU technique.