Relationship Between Pre-fresh NEFAs, Fresh Butterfat Percentage, Progesterone Levels Following Pre-Synch and Pregnancy Rates

Abstract

As herd size and milk production increase on modern dairies, it seems to be at the expense of fertility, increasing days open, declining pregnancy rates and rising cost associated with each pregnancy. To determine which service was the best time to use more expensive semen, a large commercial dairy in central Michigan investigated progesterone levels in cows following a Presynch protocol. This was followed by a prospective study, beginning with cows in the dry period, with the objective of relating pre-breeding progesterone levels to risk factors in the transition period.