Relationship between endogenous estradiol-17 beta and estrous behavior in heifers.
Thirty-five Holstein heifers were used to examine the relationship between endogenous estradiol-17 beta and estrous traits. During a non-superovulation period (NSP), estrous cycles were synchronized and during the periovulatory stage blood samples were collected every 6 h for 120 h for subsequent determination of estradiol-17 beta and progesterone. In addition, continuous observation for estrous behavior was performed for 98 h. A gonadotropin-induced superovulation period (SP) was begun 12 d after estrus was detected during NSP. Heifers were injected with FSH twice daily for 4 d and single injections of prostaglandin were given on d 14 and 15. Beginning at d 14, blood samples were collected every 6 h for 120 h for subsequent determination of estradiol-17 beta and progesterone. Continuous observation for estrous behavior was performed for 98 h. Peak estradiol-17 beta was greater during SP than during NSP (49.0 +/- 3.1 vs 12.9 +/- 3.0 pg/ml serum). Thirty-three and 31 of the 35 heifers were in estrus during NSP and SP, respectively; duration of estrus was 2.3 h longer during SP than during NSP. However, number of behavioral interactions during estrus did not differ between NSP and SP. In conclusion, estrous traits were similar, whereas peak estradiol-17 beta concentrations were markedly different between NSP and SP.
Purdue University, West Lafayette, IN 47907.
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BL
Coe
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RD
Allrich
D000818:Animals; D001522:Behavior, Animal; D002417:Cattle / Q000502:physiology*; D004958:Estradiol / Q000097:blood*; D004971:Estrus / Q000502:physiology*; D005260:Female; D011374:Progesterone / Q000097:blood; D013480:Superovulation; D013997:Time Factors
D011374:Progesterone; D004958:Estradiol