Evaluation of Different Protocols for Prostaglandin Synchronization to Improve Reproductive Performance in Dairy Herds with Low Estrus Detection Efficiency

¹ Clinic of Reproduction, Free University of Berlin, Berlin, Germany 14163
² Department of Animal Science, Cornell University, Ithaca, NY 14853-4801

The objective of this study was to evaluate different PGF₂ protocols against control protocols for herds with estrus detection efficiencies of 35, 55, and 75% using modeling and simulation: 1) PGF₂ treatments based on the presence of a corpus luteum diagnosed by rectal palpation, 2) PGF₂ treatments based on the presence of a corpus luteum diagnosed by an on-farm milk progesterone enzyme immunoassay, and 3) PGF₂ treatments based on a 14-d fixed treatment schedule without prior screening for ovarian status. After the start of each protocol, estrus detection efficiency was 75% for 7 d after treatment and 35 or 0% for the following week. For the third protocol, an additional modification at estrus detection efficiencies of 85 and 55%, respectively, in the 1st and 2nd wk after treatment was evaluated to establish a protocol for best case assumptions. All protocols improved reproductive performance relative to that of controls with estrus detection efficiencies of 35 and 55%. The mean number of days open was reduced from 124.3 d in the control herd to 95.9, 95.0, and 92.7 for the protocols based on rectal palpation, milk progesterone test, and the fixed treatment schedule, respectively. The protocols based on a fixed treatment schedule were superior to protocols based on rectal palpation and on-farm milk progesterone tests and resulted in better reproductive performance and a higher in-crease in net return per cow per year. Relative to a control herd with an estrus detection efficiency of 55%, it was cost effective to spend up to $10 per dose of PGF₂, $9 per milk progesterone test, and $6 per rectal palpation.

Key Words: prostaglandin F² • estrus synchronization • reproductive performance • estrus detection

Submitted on May 22, 1996
Accepted on April 14, 1997