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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #329670
Title: The role of progesterone concentrations during early follicular development in beef cattle: I. Characteristics of LH secretion and oocyte quality

Author
item ABREU, FERNANDA - The Ohio State University
item COUTINHO DA SILVA, M - The Ohio State University
item CRUPPE, L - The Ohio State University
item MUSSARD, M - The Ohio State University
item BRIDGES, G - University Of Minnesota
item HARSTINE, B - The Ohio State University
item SMITH, G - Michigan State University
item Geary, Thomas
item DAY, M - University Of Wyoming

Submitted to: Animal Reproduction Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2018
Publication Date: 8/28/2018
Publication URL: http://handle.nal.usda.gov/10113/6136790
Citation: Abreu, F.M., Coutinho Da Silva, M.A., Cruppe, L.H., Mussard, M.L., Bridges, G.A., Harstine, B.R., Smith, G.W., Geary, T.W., Day, M.L. 2018. The role of progesterone concentrations during early follicular development in beef cattle: I. Characteristics of LH secretion and oocyte quality. Animal Reproduction Science. 196:59-68. https://doi.org/10.1016/j.anireprosci.2018.06.020.
DOI: https://doi.org/10.1016/j.anireprosci.2018.06.020

Interpretive Summary: The objective of this study was to determine effects of progesterone during follicle growth on hormones and important signals of fertility in beef cows. Cows received either a high or low progesterone treatment during follicle growth. High and low progesterone treatments were confirmed by hormone assays of cow blood. Cows that received low progesterone treatment had high estrogen levels. Cows that received high progesterone treatment had low estrogen levels. High progesterone treated cows had smaller follicles at the end of treatment. However, these follicles grew more rapidly in the 3 days after treatment. Signals of fertility did not differ between treatments. Thus, we did improve fertility measures in cows with low progesterone treatment.

Technical Abstract: The objective was to investigate the impact of decreased progesterone (P4) concentrations during early follicular development on luteinizing hormone (LH) secretion and oocyte characteristics in beef cows. Primiparous cows (n = 24) were pre-synchronized with the 5 d CO-Synch + CIDR program and received transvaginal ultrasound-guided follicular ablation (d 0) on 6 days following the synchronized ovulation. At ablation cows were stratified by days-postpartum and assigned to either: 1) high P4 treatment - HiP4; a new CIDR was inserted on d 0 to supplement P4 from the existing corpus luteum [CL], or 2) low P4 treatment - LoP4; a previously-used CIDR and 2 doses of PGF 8-12 h apart were given (to induce luteal regression) on d 0. On d 4, CIDR were removed and ovum pick-up (OPU) was performed through ultrasound-guided transvaginal aspiration to collect oocytes from all follicles = 3 mm in diameter. Blood samples were collected on d 0, 1.5, 2.5, and 3.5 for P4, and on d 2.5, and 3.5 for estradiol (E2) concentrations. Serial blood collection (every 15 min for 12 h) was performed for LH on d 2.5 in a subset of cows (n = 13). Oocytes received a quality grade (1 to 6 scale), were stained with brilliant cresyl blue (BCB), and diameter was determined before being snap frozen for subsequent mRNA analysis of follistatin (FST). Concentrations of P4 were greater (P < 0.01) in the HiP4 than LoP4 cows on d 1.5, 2.5, and 3.5. Peripheral concentrations of E2 were greater (P < 0.05) in the LoP4 than HiP4 cows on d 2.5 and 3.5. Frequency of LH pulses was greater (P < 0.05) in the LoP4 than HiP4 cows on d 2.5, but mean LH concentration and pulse amplitude did not differ between treatments. Number of follicles aspirated per cow, total oocytes recovered, recovery rate, percentage of oocytes graded 1 to 3, oocyte diameter, percentage of oocytes that were BCB+, and the relative expression of oocyte mRNA for FST did not differ (P > 0.10) between treatments. In conclusion, decreased P4 concentrations during early follicular development increased LH pulse frequency and E2 concentrations, but did not affect known characteristics of oocyte developmental competence.