Use of Prostaglandins in a systematic reproductive management program.
Dairy Pipeline: February 1997
Ray L. Nebel
Extension Dairy Scientist, Reproduction
An excellent study conducted in New York with three commercial herds and 1624 cows compared two reproductive management scenarios using Prostaglandins (PG) with a program based on routine rectal palpation, intrauterine therapies and veterinary intervention. One program was based on the following assumptions: 1) rectal palpation is not sensitive for correctly identifying functional corpus lutea, 2) controlled studies have indicated that uterine infusions may not be beneficial, and 3) heat induced by therapeutic use of PG may cleanse the uterine environment and increase fertility. The second program included the following concepts in addition to those of the first program: 1) PG at a scheduled interval may result in synchronization of heat and improved reproductive efficiency, and 2) a higher pregnancy rate may result from PG administered at 14-day than at the original recommendation of a 11-day interval. The reproductive program which included a therapeutic injection of PG at 25 to 32 days postpartum (no rectal palpation) and another PG injection just prior to the end of the voluntary waiting period resulted in similar reproductive performance to the program consisting of routine rectal palpation and intrauterine therapies. Pregnancy rate, first service AI rate, first service conception rate, overall conception rate, percentage of cows that became pregnant, and culling rates were not different between these two programs. The second PG program combined the therapeutic PG injection at 25 to 32 days after calving with two PG injections 14-days apart for estrus synchronization and increased early heat detection. Synchronization injections were given at 39 to 46 and 53 to 60 days postpartum. Injections were given once a week to fit a convenient management schedule. Although no difference in reproductive performance occurred among programs (routine palpation group had 111 days open) partial budgeting indicated that PG treatment costs were $4.46 and $15.61 less per cow for the 2x and 3x PG programs. The increased savings with the 3x PG programs was probably due to higher heat detection efficiency as a result of estrus synchronization which did reduce days open by six days.