Improved reproductive performance from dairy cows treated with dinoprost tromethamine soon after calving

The first-service conception rate for 74 commercial dairy cows that were given a single injection of dinoprost tromethamine (prostaglandin F(2)alpha THAM) between 14 and 28 d after calving was 56%. For 74 untreated control herdmates the rate was 47%. The average interval from calving to first oestrus was 57 d for treated cows and 70 d for the control group. The difference is significant at the P = 0.017 level. The advantage in the conception rate of treated over control group cows occurred mostly in cows with a blood progesterone concentration of less than 0.5 ng/ml at the time of treatment; this numbered about two-thirds of the cows in the trial. The results support the findings of a previous study.