Synchronized Bovine Ovarian Corpus Luteum Study

Post-pubertal, non-lactating multiparous female cattle (n = 6) of composite breeding (25% MARC III [1/4 Angus, 1/4 Hereford, 1/4 Pinzgauer, 1/4 Red Poll], and 75% Red Angus) beef cows from the beef physiology herd at the Eastern Nebraska Research and Extension Center (ENREC), were used in this study. Cows were synchronized using two intramuscular injections of PGF2α (25 mg; Lutalyse, Zoetis Inc.) 11 d apart. At mid-cycle (days 9–10), the cows were treated with an intra-muscular injection of saline (n = 3) or PGF2α (25 mg; n = 9). At each of four time-points postinjection (0, 1, 2, and 4 h), three cows per treatment were subjected to a bilateral ovariectomy through a right flank approach under local anesthesia as previously described (45 (link), 73 (link), 74 (link)). The corpus luteum was removed from each ovary, weighed, and < 5 mm³ sections were snap-frozen in liquid N₂ for subsequent protein analysis or fixed in 10% formalin for immunohistochemistry. The University of Nebraska–Lincoln Institutional Animal Care and Use Committee approved all procedures and facilities used in this animal experiment and animal procedures were performed at the University of Nebraska—Lincoln, Animal Science Department.