Intraovarian effect of dominant follicle and corpus luteum on number of follicles during a follicular wave in heifers
2014
Ginther, O.J. | Hoffman, M.M.
The intraovarian relationships among dominant follicle (DF), corpus luteum (CL), and number of follicles between Days 0 to 5 (Day 0 = ovulation) in wave 1 (n = 65 waves) and Days 9 to 13 in wave 2 (n = 62) were analyzed in separate experiments in Bos taurus heifers. Ovaries were grouped into intraovarian patterns of DF–CL, DF alone, CL alone, and neither DF nor CL. In wave 1, the pattern frequencies of DF–CL or neither DF nor CL (34% each) were greater (P < 0.0004) than for DF alone or CL alone (16% each). The number of growing follicles ≥5.0 mm, was greater (P < 0.0001) in ovaries with the DF, even when the DF was removed from the tally (P < 0.03). In a factorial analysis of wave 1, there was a positive main effect of DF (3.9 ± 0.2 vs. 2.2 ± 0.2 follicles; P < 0.0001), but the main effect of CL and the interaction of DF and CL were not significant. In a factorial analysis of wave 2, there were more (P < 0.0001) follicles greater than 6 mm in ovaries with a DF when the DF was included and an approaching difference (P < 0.09) when the DF was excluded. The main effect of CL and the interaction of DF and CL were not significant. The hypothesis that both the DF and CL have a positive intraovarian effect on number of follicles in waves 1 and 2 was only partly supported; the DF, but not the CL, had an effect in the factorial analyses. Previous reports in cattle and sheep of a positive intraovarian effect of CL on number of follicles are questionable in that location of the DF was not considered.
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