title: Relationship between level of milk production and multiple ovulations in lactating dairy cows.
abstract: Our objective was to evaluate factors associated with spontaneous multiple ovulations in lactating dairy cows. Ovaries of cows [n = 267; >50 days in milk (DIM)] were evaluated weekly using ultrasound to determine spontaneous (i.e., no hormonal treatment) ovulation rate starting at 50 DIM and continuing until pregnancy diagnosis. Cows were fitted with a transmitter to record standing activity during estrus, and serum progesterone concentration was assessed weekly starting at wk 1 postpartum for all cows. Overall, 76 (28.5%) cows were anovular and 191 (71.5%) were ovular by 71 DIM. Incidence of anovulation was not associated with level of milk production but was associated with lower body condition. For anovular cows (n = 41) that spontaneously recovered, the multiple ovulation rate at first ovulation was 46.3%. For second and subsequent ovulations (n = 463), the level of milk production for 14 d preceding estrus was associated with increased ovulation rate. To illustrate, incidence of multiple ovulations was 1.6% (2/128), 16.9% (32/189), and 47.9% (70/146) for ovulations when cows were producing <35, 35 to <45, and >or=45 kg/d, respectively. Among cows for which estrous behavior was recorded, those with multiple ovulations (n = 48) had shorter duration of estrus (4.3 +/- 0.7 vs. 9.9 +/- 0.5 h) and higher production (47.2 +/- 0.9 vs. 38.1 +/- 0.5 kg/d) than cows with single ovulations (n = 237). Circulating concentrations of estradiol were lower (5.5 +/- 0.3; n = 15 vs. 7.8 +/- 0.4 pg/mL; n = 71) during periods of estrus with multiple ovulations despite a greater preovulatory follicular volume (4136 +/- 123 vs. 3085 +/- 110 mm(3)). Similarly, serum progesterone concentration 7 d after estrus was lower for cows with multiple than single ovulations (2.5 +/- 0.3 vs. 3.2 +/- 0.1 ng/mL) despite a greater luteal volume (8291 +/- 516 vs. 6405 +/- 158 mm(3)). In summary, the first spontaneous ovulation in anovular cows and a higher level of milk production for 14 d preceding estrus were associated with increased multiple ovulation rate. Additionally, cows with multiple ovulations had lower estradiol at estrus, a shorter duration of estrus, and lower progesterone at 7 d after estrus than cows with single ovulations.
authors: Department of Dairy Science, University of Wisconsin, Madison 53706, USA.
authors: H
authors: H
authors: Lopez
authors: D Z
authors: DZ
authors: Caraviello
authors: L D
authors: LD
authors: Satter
authors: P M
authors: PM
authors: Fricke
authors: M C
authors: MC
authors: Wiltbank
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000000981:diagnostic imaging; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000502:physiology; D005260:Female; D007774:Lactation / Q000502:physiology*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging; D010060:Ovulation / Q000502:physiology*; D010298:Parity; D049590:Postpartum Period; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012044:Regression Analysis; D014463:Ultrasonography / Q000662:veterinary
chemical_list: D011374:Progesterone; D004958:Estradiol