Effect of progesterone supplementation following TAI on pregnancy per AI in dairy cows

Abstract

Lactating Holstein cows (n=102: primiparous [n=41] and multiparous [n=61]) were blocked by parity, and then allocated to control (n=51) and CIDR (n=51) groups. In both groups, timed artificial insemination (TAI) was done following Presynch-Ovsynch, and pregnancies were diagnosed with ultrasonography (USG) 32 days after TAI. Diameter (mm) of corpus luteum (CL) were determined with USG eleven days after TAI. In CIDR group, CIDR was inserted and removed four and eighteen days after TAI, respectively.