This dissertation explores the complex mechanisms involved in the ability of a dairy cow to undergo parturition and then become pregnant once again in less than 3 months. This critical period in a cow's life is when the herd veterinarian spends most of their time ensuring this period is not fraught with problems that may impact the ability for this cow to become pregnant again. The first chapter reviews the importance of both ovarian and uterine physiology during this important period. The physiology of follicular and luteal function changes rapidly from parturition until 1 to 2 months later. Cows will generally have an ovulation and begin estrous cycles from 15 to 45 DIM. But a substantial percentage of cows will not have an ovulation before this time. We refer to these cows as "anovular" because they are not ovulating. Anovulation can be detrimental to the chances of a pregnancy following first AI as pointed out in Chapter 1. In addition, what transpires with regard to ovarian function also can have a direct impact on uterine physiology. In Chapter 2, the literature regarding the problem of endometritis on the health, welfare and chances of a pregnancy is presented. It was clear from this literature review that endometritis increases the time to pregnancy thus increasing the chances of cows leaving the herd too soon. This costs dairy producers a significant amount of money. Chapter 3 proposes a systematic way to solve the two main issues discussed in Chapters 1 and 2 with a hypothesis that utilizing GnRH and PGF2 in tandem could resolve both the anovulatory condition of cows in addition to endometritis. Outcomes were clear that this strategy actually decreased fertility of primiparous lactating cows. The final chapter of this dissertation, Chapter 4, summarized the impact of a fertility program initiated at Rolling Acres Farm in Michigan. The impact of the fertility program, G6G, on a number of outcomes is described.
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