title: Accurate ultrasonographic prediction of progesterone concentrations greater than 1 ng/ml in Holstein lactating dairy cows.
abstract: To develop an ultrasonographic assay for determining plasma progesterone concentration (P4 ) as < 1 ng/ml or ≥ 1 ng/ml, the corpus luteum (CL) area and P4 were measured in 1094 multiparous Holstein cows. The area-measuring function and frozen images were used to outline and measure CL imaged via ultrasonography, and CL area was estimated as a polygon of a continuation straight line. A significant correlation was found between CL area and P4 (p < 0.001), and this analysis resulted in the following correlation equation: y = -0.35 + 1.02x (r = 0.81). According to the correlation equation, a CL area of 1.3 cm(2) indicated a P4 of 1 ng/ml. Based on this relationship, each animal was categorized into one of six groups, groups differed based on CL area, and the area ranges were as follows: < 1.3 cm(2) (Group A), 1.3-2.2 cm(2) (Group B), 2.3-3.2 cm(2) (Group C), 3.3-4.2 cm(2) (Group D), 4.3-5.2 cm(2) (Group E) and > 5.2 cm(2) (Group F). For each group, the proportion of cows whose P4 was 1 ng/ml or more was 1.5% in Group A, 83.3% in Group B, 76.6% in Group C, 96.6% in Group D, 99.2% in Group E and 100% in Group F. There was a significant difference between Group A and the other five groups, and between Groups B or C and Groups D, E or F (p < 0.005). These results indicate that a functional CL does not exist when the CL area is less than 1.3 cm(2) and that it exists when the CL area is 3.3 cm(2) or more.
authors.affiliation: Department of Veterinary Obstetrics and Gynecology, Azabu University, Chuo-ku, Sagamihara, Kanagawa, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kaneko
authors.forename: N
authors.initials: N
authors.lastname: Takagi
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000000981:diagnostic imaging*; D005260:Female; D007774:Lactation / Q000502:physiology*; D011374:Progesterone / Q000097:blood*; D014463:Ultrasonography
chemical_list: D011374:Progesterone