Corpus Luteum Development and Function in Cattle: RESULTS(1)

Treatment with bLH to mimic a preovulatory surge of LH resulted in concentrations of LH in circulation above 50 ng/ml in all females (Fig. 1). Data for mean concentrations of LH in circulation during the 3-h treatment with purified bLH are included in Table 1. Ovulation was successfully induced in 16 females within 48 h after treatment with bLH (untreated control = 5; Ant 2 = 4; Ant 0 = 4; Ant —2 = 3); and three more females (Ant 2 = 1; Ant 0 = 1; Ant —2 = 1) ovulated within 72 h after treatment with bLH. Two females in the Ant — 2 group did not ovulate. These females, however, had ovarian follicles 10 mm or greater in diameter that were potentially capable of ovulating when the LH treatment was administered.

Average size of the largest follicle at the time of treatment with LH was 11.8 ± 1.0, 9.2 ± 0.4, 10.5 ± 1.6, and 12.8 ± 0.9 for the control, Ant —2, Ant 0, and Ant 2 groups, respectively. Day of detection of the behavioral estrus after time of treatment with LH to induce ovulation was Day 20 ± 1, 29 ± 3, 27 ± 2, and 24 ± 2 in females from the control, Ant —2, Ant 0, and Ant 2 groups, respectively.
Fig1Corpus Luteum Development
FIG. 1. Concentrations of LH in blood plasma of cattle treated with LHRH antagonist at different times relative to the preovulatory LH surge (Day 0 = day of exogenous LH surge).

TABLE 1. Number of animals that had ovulations from dominant follicles, basal and mean concentrations of LH in blood plasma and area under the profile of progesterone concentration during the luteal phase of the estrous cycle of cattle treated with LHRH antagonist and untreated control females.

Treatments
Parameter Control Ant —2 Ant 0 Ant 2
n (ovulated) 5 6 5 5
Basal LH before the surge (ng/ml ± SEM) 2.50 ± 0.06a 0.71 ± 0.01b 1.42 ± 0.06c 2.50 ± 0.1a
Mean LH during the surge (ng/ml ± SEM) 68.8 ± 1.6 61.2 ± 1.2 60.2 ± 1.4 65.7 ± 1.2
Progesterone under the curve (arbitrary units ± SEM) 142.2 ± 9.6b 19.6 ± 1.6a 41.6 ± 2.3a 43.6 ± 1.9a

a,b,c p < 0.01.

This entry was posted in Corpus Luteum and tagged Corpus Luteum, Estrous Cycle, Luteinizing Hormone.