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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #208202
Title: Increasing ovulation rate reduced follicle size and increased blood progesterone concentrations but had no effect on fertility in cattle selected for twins

Author
item Echternkamp, Sherrill
item Cushman, Robert
item Allan, Mark

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2007
Publication Date: 6/20/2007
Citation: Echternkamp, S.E., Cushman, R.A., Allan, M.F. 2007. Increasing ovulation rate reduced follicle size and increased blood progesterone concentrations but had no effect on fertility in cattle selected for twins [abstract]. Journal of Animal Science. 85 (Supplement 1):649. (Abstract #886)

Interpretive Summary:

Technical Abstract: Smaller ovulatory follicles (F) and lower progesterone concentrations during the luteal phase after breeding reportedly decrease fertility and embryonic survival in cattle. Diameter (diam.) of individual F and corpora lutea (CL), blood progesterone concentrations, and conception to AI were compared among cows with ovulation rate (OR) records of one (n = 74), two (n = 253), three (n = 88), or four (n = 6) CL in 2004 to 2006; herd mean for OR was 2.09. Number and diam. of F and subsequent CL were determined by ultrasonography at 12 h after onset of estrus and 8 to 15 d after AI, respectively, and number of fetuses at 60 d after AI. Progesterone was quantified by RIA in a single blood sample collected at CL diagnosis. Data were analyzed by SAS PROC MIXED procedures; main effects in the models were OR, day, fetal status, and year. Follicle diam. was smaller (P < 0.01) in 2006. Follicle and CL diam. were correlated (r = 0. 53; P < 0.01) and decreased (P < 0.01) with increasing OR (1 CL = 17.1 ± 0.3 and 23.3 ± 0.4 mm, 2 CL = 14.0 ± 0.1 and 20.2 ± 0.4 mm, 3 CL = 12.6 ± 0.2 and 18.1 ± 0.3 mm, 4 CL = 11.7 ± 0.5 and 16.7 ± 0.7 mm, respectively), but diam. were similar for fertile (fetus) and infertile ovulations (13.9 ± 0.1 and 19.8 ± 0.4 mm vs. 13.8 ± 0.1 and 19.4 ± 0.4 mm, respectively). Fetal number per female increased (P < 0.01) with OR (0.52 ± 0.8, 1.07 ± 0.5, 1.52 ± 0.6, and 1.63 ± 1.0 for 1, 2, 3, and 4 CL, respectively), but the fetus:ovulation ratio (0.52 ± 0.3) was unaffected by OR. OR did not affect pregnancy rate (65.6 ± 0.3%) at d 60. Progesterone concentrations increased (P < 0.01) with OR (1 CL = 7.1 ± 0.3, 2 CL = 8.9 ± 0.2, 3 CL = 9.7 ± 0.3, 4 CL = 8.5 ± 0.7 ng/ml) and from d 8 (6.3 ± 0.5 ng/ml) to 14 (10.6 ± 0.5 ng/ml). Concentrations did not differ between pregnant and nonpregnant cows (8.8 ± 0.3 vs. 8.2 ± 0.3 ng/ml). Decreased follicle size and increased progesterone in cows with natural multiple ovulations did not affect conception.