Corpus Luteum Development and Function in Cattle: RESULTS(2)

RESULTS(2)

Day of detection of behavioral estrus was earlier (P < 0.05) in females of the control group than in females in any of the treated groups, and earlier (P < 0.05) in the Ant 2-treated females than in the females of the other two treated groups.

Maximum diameter of the CL during the luteal phase of the estrous cycle when treatments were administered was greatest (P < 0.01) in untreated control females (28.8 ± 1.2) and smallest in females from the Ant —2 (9.5 ± 0.4) group (Fig. 2). Maximum diameter of the CL in females of the Ant 0 (17.5 ± 0.7) and Ant 2 (21.6 ± 0.8) groups during the luteal phase of the estrous cycle was less than in females of the control group (28.8 ± 1.2) but greater (P < 0.01) than in females of the Ant —2 group (9.5 ± 0.4). There was no difference (P > 0.1) in maximum diameter of the CL among females of the Ant 0 or Ant 2 group during the luteal phase of the estrous cycle when treatments were administered.

Values for concentrations of progesterone during the luteal phase of the estrous cycle were tested for homogeneity of variances using the Bartlett test. Variances were homogeneous among groups, and transformation of data was not required. Compared with concentration of progesterone (area under the curve) in females from the control group, concentration of progesterone during the luteal phase of the estrous cycle was less (P < 0.01) in females in which LH release was inhibited prior to, during, or after the LH surge (Fig. 3). For females in which LH release was inhibited (starting 48 h before the preovulatory LH surge, or at the time of its initiation, or 48 h afterward) and for the control group, arbitrary units under the curve for progesterone concentrations during the luteal phase of the estrous cycle were 19.6 ± 1.6, 41.6 ± 2.3, 43.6 ± 1.9, and 142.2 ± 9.6, respectively. There was no difference (P > 0.1) in concentrations of progesterone during the luteal phase of the es-trous cycle as determined by arbitrary units of progesterone in females of the three groups in which release of LH was inhibited by using LHRH antagonist.
Fig2Corpus Luteum Development
FIG. 2. Diameter of the CL in untreated control females and females treated with an LHRH antagonist at different times relative to the time of the preovulatory LH surge (Day 0 = Day of exogenous LH surge); data depicted by lines (for area under the progesterone concentration profile during the estrous cycle) indicated by different letters differ; a-c: P < 0.01.

Fig3Corpus Luteum Development
FIG. 3. Mean concentration of progesterone in blood plasma from untreated control females and females treated with an LHRH antagonist at different times relative to the preovulatory surge of LH (Day 0 = Day of exogenous LH surge); control group is different from treated groups, P = 0.01.

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