Plasma progesterone, T3 and T4 concentration at the time of insemination and conception rate in normal and repeat breeding dairy cattle

Abstract

A study was undertaken to asses the blood plasma progesterone (P4). triiodothyronine (T3) and thyroxine (T3) levels at the time of insemination and conception rate (CR) in normal and repeal breeding (RB) dairy cattle. At the time of insemination detailed history of previous insemination and the time of onset of that particular estrus were obtained from the herdsman and estrus was confirmed based on the gynaecological examination. These animal were inseminated with frozen semen hy a single inseminator. Just before insemination blood samples were collected, centrifuged and plasma was analyzed for P4, T3and T4 concentration. All the inseminated animals were examined per rectally after 45-60 days of insemination pregnancy diagnosis. Results revcaled that 8.33 and 72.73% of normal and RB cattle, respectively, had more than nmol/L of P4, level at the time of inseminatian. On then contrary, significantly higher proportion of RB catlle (29.5% vs10.4% in normal) had low T3 levels (&lt1 ng/ml)and of the cattle in this group only 2 conceived. Similarly, the proportion of cattle having high T4 levels (&gt20 ng/ml) was significantly higher in normal group (39.5%) When compared to RB group (11.36%). The overall CR in normal and RB groups were 41.66 and 18.18% respectively.