Efficiency of measuring corpus luteum crosssectional areas by ultrasonography for detecting early pregnancy in cattle

ABSTRACT

The obj e ctive of this study was to examine the efficiency of a novel method of early pregnancy diagnosis in cows. This method was based on cross - sectional area change s of corpora lutea measured by t ransr ectal ultrasonography. One hundred forty one Japanese Black cows were artificially inseminated and divided into four groups according to examination days . Corpora l utea of all cow s in each group were measured twice at 7 days apart, on days 13 and 20 (n = 1 8 ), 14 and 21 (n = 40 ), 15 and 22 (n = 37 ) and 16 and 23 (n = 46 ) post - insemination. Confirmation of pregnancy was performe d by ultrasonography on day 30 post - insemination . All non - pregnant cows showed clear regression of t heir c orpora l utea at rates of 35. 8 , 43.7 , 51. 3 , and 56.2 % on days 20, 21, 22 , and 23 post - insemination, respectively . Some ovarian disorders were discovere d in 9% of non - pregnant cows. In conclusion, the present method was hig hly sensitive (100%) in detecting ear ly non - pregnancies in the field , and also helpful in detecting ovarian disorders at an early stage, which gives reason to use it for better economic management and benefit.