Effect of new and reused CIDRs on serum progesterone concentrations in lactating dairy cows

Abstract

Despite the common practice of re-using a popular intravaginal progesterone releasing device by United States cattle producers, there is little published scientific evidence whether this practice is effective as an aid in synchronizing oestrus. The study was conducted to determine the effect of new and reused CIDRs containing 1.38 g progesterone on the serum progesterone concentrations in cows that received the same CIDR twice in succession. 40 cows were divided into three treatments as T1 (n=18), T2 (n=15) and T3 (n=7). Prior to the start of each trial, 5.0 ml dinoprost was injected to each cow, then serum samples were collected for progesterone measurement on the same day. Results revealed that 37 samples had serum progesterone concentrations of >1.1 ng/ml and the average serum progesterone concentrations of T1, T2 and T3 were 2.7243, 4.0973 and 2.7027, respectively. It was observed that the mean serum progesterone concentrations on days 2 and 3, days 5 and 6 and days 8 and 9 were significantly different and varied between trials. Serum progesterone concentrations associated with used CIDRs were statistically similar to baseline progesterone concentrations obtained from cows before new CIDR insertion. It is suggested that there is either significant loss of progesterone in the CIDR insert after one use or decrease absorption of progesterone available from the used CIDRs, and the reuse of 1.38 g CIDRs to aid in synchronization of oestrus in lactating dairy cattle is not recommended.