Effect of noise on blood levels of LH and progesterone, estrus and ovulation in heifers.

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Two Holstein heifers (Cow 1 and 2) were experimentally exposed to an intermittentnoise, 70-75 phones at 1 hr intervals, throughout an estrous cycle. Duration of estrus, number of ovulation, and blood concentrations of LH and progesterone were compared with those obtained in pre-and post-treatment estrous cycles. The results obtained in the three successive estrous cycle were as follows.<BR>1) In the first cycle, pre-treatment control cycle, ovulation was detected by rectal palpation 32 hr after the onset of estrus in both the two heifers. Typical LH surge, followed by an increase of progesterone during the luteal stage was observed.<BR>2) In the second cycle, the noise-loading cycle, duration of estrus was prolonged as compared with previous cycle and ovulation took place 72 hr after the onset of estrus. Although two ovulations were confirmed in both heifers, LH surge was not observed in Cow 1 during the 60 hr observation period. Blood progesterone level in the subsequent luteal phase showed a normal change.<BR>3) In the third cycle, post-treatment cycle, duration of estrus was reduced toward the pre-treatment value and the ovulation was confirmed 46 hr after the onset of estrus.<BR>The present results indicate that the noise stress can affect reproductive function such as LH secretion, duration of estrus and thus timing of ovulation in heifers.
日本繁殖生物学会の論文