Superovulation before and after the removal of, one ovary from cows with or without a history of twin calving

摘要

Abstract Three superovulation trials were carried out in cows with (1') or without (C) a history of twin calvings. There were six T and eight C cows. In Trial 1, 12 or 20 mg doses of follicle stimulating hormone (FSH-P) were administered to synchronised cows over a 5-day period in a declining dose regime. In the luteal phase of the cycle after superovulation, corpora lutea (CL) data were collected by ovarian palpation per rectum, and blood samples were taken to determine plasma progesterone concentratIons. Immediately after palpation, Trial 2 was begun with the removal of one ovary from each cow (left or right side being pre-determined at random for T and C cows). The protocol for superovulation, and subsequent collection of CL data and blood samples, were then similar to Trial 1. Ten weeks after the end of Trial 2, the superovulation experiment was repeated on the same cows (Trial 3). Natural ovulations recorded before Trial 1 showed that three out of 11 records (27%) from T cows and none out of 11 from ...