Abstract
Cows treated with single doses of follicle stimulating hormone (FSH) and ovum pick up (OPU) after 24 hours were evaluated for oocyte recovery, in vitro production of embryos (IVPE), and transferred embryos. To begin evaluations, the ovarian follicles larger than three millimeters in diameters were removed from all cows used in the study. Two days after OPU, 200 milligrams of FSH was given in a single dose in 6 cows (treated). Twenty-four hours after application of FSH, the cows underwent a new OPU session for oocyte retrieval. These procedures were repeated three consecutive times without interval. In control (FSH-free) cows the OPU were performed at intervals of one week or oocyte retrieval. The viable oocytes were submitted to IVPE, and the blastocysts were transferred to the recipients. The mean number of oocytes did not differ (p > 0.05) between control cows (12.1±2.8) and those treated (10.9±1.6). There were also no differences (p > 0.05) in the number (6.6±1.7 and 7.1±0.9, respectively) or in the percentage (54.4±3.3 and 64.5±3.1%, respectively) of viable oocytes between control cows and those treated. The percentage of IVPE and pregnancy did not differ (p > 0.05) between control cows (39.8±2.6% and 44.7±4.8%) and those treated (37.8±2.5% and 39.5±4.1%), respectively. The treatment with single doses of FSH did not significantly alter the evaluated results for oocyte recovery, IVPE and transferred embryos, and, therefore, did not promote significant improvements for the IVPE as a whole.
Highlights
In bovine, groups of follicles are continuously recruited throughout the reproductive life during ovarian cycles, with the development of two or three dominant follicles per cycle
Follicle stimulating hormone treatment can be used as an alternative to oocyte recovery through ovum pick up in order to minimize negative effects resulting from the settling of the dominant follicle (Ginther, Siddiqui, Baldrighi, & Araujo, 2017; Goodhand, Watt, Staines, Hutchinson, & Broadbent, 1999)
Girolando donor dairy cows were used to test the effects of single dose follicle stimulating hormone treatment, followed by ovum pick up after 24 hours of hormonal application
Summary
Groups of follicles are continuously recruited throughout the reproductive life during ovarian cycles, with the development of two or three dominant follicles per cycle (two or three follicular waves/cycle). Follicular dominance is associated with a reduction in plasma concentration levels of follicle stimulating hormone; the subordinate follicles interrupt their growth, become atretic, and the recruitment of new follicles is blocked, a fact that reduces the number and quality of the initially recruited follicles (Adams, Jaiswal, Singh, & Malhi, 2008; Kim et al, 2001) These ovarian events have generated broad interest in the reproductive biotechnology field, which aims to develop hormonal protocols for ovarian stimulation that are able to support follicular growth, in order to prevent follicles from becoming atretic, and to enable the collection of a larger number of oocytes to be used in embryo production in vitro (Khan, Pinaffi, Beg, & Ginther, 2012). The aim of the current study was to investigate oocyte-donor Girolando cows, treated with follicle stimulating hormone in single doses and ovum pick up 24 hours after the application of the hormone, with additional treatments every three days, to assess oocyte recovery, in vitro embryo production, and the percentage of pregnancy after transfer
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