Effect of ovariectomy and ovariectomy with ovarian autotransplantation on feedlot performance and carcass characteristics of heifers.

Feedlot growth performance and carcass characteristics were examined in 96 crossbred heifers of continental breeding. Heifers were assigned to four treatment groups: intact control, sham ovariectomized, ovariectomized, and ovarian autografted. Ovarian autografted heifers were bilaterally ovariectomized via a left flank incision and one ovary was bisected sagittally and implanted in the musculature of the flank. Animals were fed a diet based on corn silage and were slaughtered at a weight of about 450 kg. There was no effect of treatment on feedlot performance or objectively measured carcass traits. However, carcasses of ovariectomized and ovarian autografted heifers had lower maturity scores than carcasses of the intact and sham-ovariectomy heifers. Blood samples were collected monthly throughout the study. Progesterone concentrations in these samples indicated that approximately 20% of the ovarian autografted heifers exhibited ovarian cyclicity. Examination of the transplanted ovaries at slaughter indicated that approximately 20% of the transplanted ovaries were resorbed. Cavitated, fluid-filled, thick-walled structures that were considered to be luteinized follicles were the most prominent structures found on the transplanted ovary; these were found in one-third of the ovarian autografted heifers. These results indicate that an ovary transplanted to the musculature can remain viable; however, its physiological function is disrupted and it does not affect rate or efficiency of gain or carcass composition compared to ovariectomized heifers.