Journal
THERIOGENOLOGY
Volume 111, Issue -, Pages 52-55Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.theriogenology.2018.01.011
Keywords
Gonadotropin; eCG; hCG; Follicle; Cattle
Categories
Funding
- Sao Paulo Research Foundation (FAPESP) [2013/26956-3]
- National Council for Scientific and Technological Development (CNPq) of Brazil
- Coordination for the Improvement of Higher Education Personnel (CAPES)
- CNPq [460902/2014-8]
Ask authors/readers for more resources
The aim of this study was to evaluate the effect of eCG or hCG on the final growth of the dominant follicle in Nelore (Bos indicus) cows submitted to fixed-time Al (FTAI). Eighty-four lactating cows with body condition score (BCS) of 2.9 (range 1-5) were used. At a random day of the estrous cycle (DO) cows received 2 mg estradiol benzoate and a reused intravaginal progesterone device (1.9 g). At D8, when the device was removed, 0.5 mg cloprostenol and 1 mg estradiol cypionate was given i.m., and cows were randomly assigned to receive on D8 one of the following treatments: Control (no treatment; n = 17), eCG (300 IU i.m.; n = 17), hCG 300 (300 IU i.m.; n = 18), hCG 2001M (2001U i.m.; n = 16) and hCG 200 SC (200 IU s.c.; n = 16). On the same day and 2 days later, cows were subjected to ovarian ultrasonography to evaluate the diameter of the largest follicle and to calculate follicular growth rate (D8 to D10). No differences were observed for the diameter of the largest follicle on D8 (P = 0.3) or D10 (P = 0.4) among treatments. However, the growth rate of the dominant follicle between D8 and D10 was greater for the groups eCG and hCG 300 and there were no differences between the other treatments (Control = 1.1 mm/day; eCG = 1.8 mm/day; hCG 300 = 1.8 mm/day; hCG 200 IM = 13 mm/day; hCG 200 SC =1.3 mm/day; P = 0.02). In addition, more cows from the Group hCG 300 presented premature ovulation (44.4%) than cows from Control (5.8%), eCG (0%), or hCG 200 IM (12.5%), but did not differ from Group hCG 200 SC (18.7%). Regardless of treatment, the size of the largest follicle on D8 was different between cows that presented premature ovulation vs. cows that did not ovulate prematurely (11.3 mm vs. 9.9 mm, respectively; P = 0.01). Treatment with different hCG doses on D8 of a FTAI protocol failed to produce similar effects compared to eCG in terms of final follicular growth support and greater ovulatory follicle size. In addition, the groups hCG 300 and hCG 200 SC induced premature ovulation in a greater portion of cows. Thus, a single administration of hCG on D8 does not appear to be a reliable alternative to eCG treatment in FTAI protocols. (C) 2018 Elsevier Inc. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available