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|Title:||Physiological Responses of Holstein Cows to Three Superovulatory Methods|
|Department / Program:||Dairy Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Biology, Animal Physiology|
|Abstract:||A study was conducted on 42 Holstein cows to: (1) assess the superovulatory efficacy of continuous follicle stimulating hormone (FSH) administration subcutaneously (SC) via osmotic pumps, (2) assess the benefits of gonadotropin releasing hormone (GnRH) administration on the day of expected estrus and (3) determine the relationship of vaginal electrical resistance (VER) to the time of estrus and to other variables.
Forty-two cows which exhibited natural or prostaglandin F(,2(alpha)) (PGF(,2(alpha))) induced estrus were assigned to one of three superovulatory treatments. Group I (control) received 50 mg of FSH intramuscularly (IM) in twice daily doses over five days. Group II received the same treatment as Group I plus 250 ug of GnRH. Blood samples were collected on Days 1, 3 and 5 from seven cows in each group for analysis of luteinizing hormone (LH) concentration. One sample was also collected from each cow on the day of flushing for progesterone concentration analysis. All cows received 25 mg of PGF(,2(alpha)) on the third day of superovulation and each was inseminated with two units of frozen semen from a single high fertility bull.
Results indicated that continuous SC infusion of 7 mg of FSH per day for 7 days can superovulate cows. However, fewer corpora lutea (CL) were palpated and fewer embryos were recovered from this group. These differences were attributed to differences in doses, method and route of FSH administration. A higher percent of developing embryos were recovered from GnRH-treated than from untreated cows. There was a high correlation between the numbers of CL and numbers of embryos, between progesterone and the number of CL and between progesterone and the number of embryos. On Day 3, there was a treatment by time interaction as LH increased between 1200 and 1600 hr in Group III, while in Groups I and II it declined. The magnitudes of LH surge were not different among the three treatments. Superovulatory responses were not affected by synchronization of estrus. Cows in which LH surge was detected tended to have higher numbers of CL and embryos. VER values varied daily within and among groups. VER was not highly correlated with serum LH concentration or the number of CL palpated or the number of embryos recovered. However, low VER was associated with the day of estrus.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
|Date Available in IDEALS:||2014-12-16|