Short communication: characterization of early postpartum estrous behavior and ovulation in lactating dairy cows using radiotelemetry.
The objective of this study was to describe early postpartum estrous behavior and ovulation in lactating dairy cows using radiotelemetry. Cows (n=50) were continuously monitored for behavioral estrus with a radiotelemetric system, HeatWatch II (CowChips LLC, Manalapan, NJ), from d 14 to approximately d 49 postpartum. Blood collection for analysis of progesterone and ovarian ultrasonography were performed once weekly starting on d 14. First ovulation was associated with behavioral estrus in 5 cows and occurred at 28.2±10.8 d (mean±SD; range 17 to 40 d). The average duration of estrus was 6.0±4.9 h (range 3 to 12.2 h), and the mean number of standing events was 18.4±8.9 (range 4 to 26). Based on progesterone concentrations of ≥1 ng/mL, estimated first postpartum ovulation occurred at 25.1±10.4 d (range 10 to 49 d) for 38 animals without evidence of behavioral estrus. The interval to estimated first ovulation without behavioral estrus was not different from the interval to first ovulation associated with behavioral estrus. Level of milk production and body condition score loss did not affect the interval to estimated first ovulation without estrus or first ovulation associated with estrus. Six animals did not show evidence of ovulation based on progesterone concentration, whereas 1 cow showed evidence of estrous behavior on the day before removal from the study. The majority of first postpartum ovulations (38/43; 88.4%) were not associated with behavioral estrus.
Animal and Veterinary Science Department, University of Idaho, Moscow 83844.
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Johnson
Animal and Veterinary Science Department, University of Idaho, Moscow 83844.
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Ayers
Animal and Veterinary Science Department, University of Idaho, Moscow 83844.
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Ahmadzadeh
Statistical Programs, College of Agriculture and Life Sciences, University of Idaho, Moscow 83844.
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B
Shafii
University of Idaho Extension, Caldwell 83605.
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Etter
Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
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Chebel
Animal and Veterinary Science Department, University of Idaho, Moscow 83844. Electronic address: jdalton@uidaho.edu.
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Dalton
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002417:Cattle / Q000502:physiology* / Q000523:psychology; D004971:Estrus / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D010060:Ovulation / Q000502:physiology* / Q000523:psychology; D049590:Postpartum Period / Q000502:physiology* / Q000523:psychology; D011187:Posture; D011374:Progesterone / Q000097:blood; D013686:Telemetry / Q000379:methods / Q000662:veterinary*
D011374:Progesterone