Based on the mechanisms controlling reproduction in early pregnancy, approaches were developed to improve fertility that involve use of interferons, hCG, GnRH analogues, progestins and bST. In joint research efforts with several laboratories, the efficacy of interferon-τ for improving pregnancy rates was tested. While results were un-encouraging, these experiments represent critical studies of this type and set the stage for other experiments with interferon-τ. A patent claiming such uses of interferon has been issued by the U.S. Patent Office. Beneficial effects of hCG on pregnancy rate have been found, however. The benefit of hCG injections in field studies to improve conception rates is due likely to its ability to induce a highly functional accessory CL when given on day 5 after insemination and altering the follicular wave patterns (i.e., 2 wave to 3-wave cycles). The induced accessory CL secretes appreciable amounts of progesterone, and all cows have three follicular waves. As a consequence, conception rates are increased approximately 6 % in lactating dairy cows. Additional work is currently in progress with use of GnRH agonist implants and results are encouraging in that GnRH agonist implants induce ovulation as part of a timed insemination program, stimulates functional development of the CL, and attenuates follicular development during the period when the conceptus is suppressing the secretion of PGF_2αby the uterus.

Additional strategies to improve embryo survival have been developed after having optimized timed insemination programs. For example injection of bST (i.e., Posilac, Monsanto, St. Louis) at the time of insemination of a Pre-Synch/Ovsynch program increases pregnancy rates by ˜ 10% in lactating dairy cows. Additional research indicates that bST appears to stimulate embryo development.

Recent estimates on the economic impact of the various reproductive management options determined by Stochastic Modeling have been estimated. Increase in net revenue per lactating dairy cow with the use of Ovsynch, Presynch/Ovsynch and Presynch/Ovsynch +bST are: $37.90, $80.80 and $130.70 respectively (Overton, Michael, Personal Communication). These estimates represent substantial increases in net revenue for producers.

Working in close cooperation with Dr. Charles Staples, we have integrated systems of reproductive and nutritional management. Following extensive experiments involving fat feeding, polyunsaturated fatty acids (i.e., EPA and DHA) in fish oil were identified as being able to suppress the uterine secretion of PGF_2α. These basic studies have led to ongoing field studies to determine if calcium salts of EPA and DHA will specifically improve embryo survival (e.g., cooperative studies with Santos, Jose, University of California, Davis-Tulare). Results look encouraging and such approaches involving targeting of specific nutrients to improve reproductive function may change markedly management approaches to improve pregnancy rates.