The Change in Luteal Blood Flow and Luteal Size after Beta Carotene and GnRH Injections in Early Pregnant Dairy Cows

Abstract

The aim of this study was to determine the effectiveness of intramuscular injections of beta-carotene (beta C) and GnRH on luteal size (LS), luteal blood flow (LBF) and serum beta C concentrations in early pregnant cows. Twenty-nine Holstein-Friesian cows with a mature corpus luteum (>19mm) were randomly assigned to two groups: pc not received (beta C-; n=15) or received (beta C-; n=14). All cows were treated with PGF(2)alpha and inseminated twice, 48 and 72h after the treatment. Last Al was considered to be day 0. All cows received GnRH on day inseminations, 7 and 17. Different from the beta C-, the beta C+ group received beta C intramuscularly on day 7 and 17. In both groups, measurement of LS and LBF were performed on days 7, 10, 17,27 and 37 by transrectal B-mode and colour Doppler ultrasonography. Blood samples were collected on each examination day. Only cows that became pregnant were included in the statistical evaluation. The concentration o beta C in the beta C+ group was higher than in the beta C- at all examination days except day 17 (P<0.05). There was no significant difference between groups concerning the progesterone concentrations (P>0.05). The LS and LBF of beta C+ group on day 7 (P<0.05) and 27 (P<0.01) was higher than in the beta C- group and values increased significantly until day 37 (LS: P<0.05, LBF: P<0.01). We conclude that beta C injections significantly increased serum beta C concentrations, as well as LS and LBF.