Keys to Successful Estrus Synchronization and Artificial Insemination Programs

Introduction The development of effective methods of synchronizing estrus and ovulation has been based on our understanding of the physiological and hormonal mechanisms controlling the estrous cycle and the initiation of estrous cyclicity and prepuberty in heifers and postpartum cows. Although estrus synchronization products (PGF2, MGA, CIDR and GnRH) and protocols have changed over time, the basic physiological principles underlying how these products work have not. An understanding of how these products impact the bovine estrous cycle and an understanding of how management decisions impact pregnancy success will have an effect on the success of any reproductive program. Estrus synchronization and artificial insemination (AI) are among the most powerful and applicable technologies for genetic improvement of beef herds (Seidel, 1995). When we consider the food demands to feed the 9 billion people expected to be on the earth in 2050 the efficiency of beef production needs to increase or beef may become a luxury item and not a commodity to feed the world. Beef is currently 22% of the world meat production, and with meat production estimated to need to be over 455 million tons to feed the 2050 population beef production will need to double to maintain its current share of the production system. In addition, as the cost of production increases the importance of maintaining your cow herd also increases. Research has indicated it takes the net revenue from approximately 6 calves to cover the development and production costs of each replacement heifer (E. M. Mousel Unpublished data). In addition, any cow that misses a single calving is not likely to recover the lost revenue of that missed calf (Mathews and Short, 2001). Therefore, longevity of a beef female is important to the sustainability and profitability of any beef operation. Considering the importance of longevity, an important question is as follows: Why are females culled from a beef herd? According to the 2007-08 NAHMS survey the greatest percentage of cows culled from the herd was due to pregnancy status (33.0%); other reasons for culling included age or bad teeth (32.1%), economic reasons (14.6%), other reproductive problems (3.9%), producing poor calves (3.6%), temperament (3.6%), injury (2.9%), udder problems (2.7%), bad eyes (1.8%), and other problems (1.8%). Therefore, understanding how management decisions impact pregnancy success and longevity will have an effect on the profitability and sustainability of an operation. When it comes to reproductive management the things you do well will not compensate for the mistakes you make. Instead, the mistakes you make cancel out all the things you do well. This is best illustrated by examining the primary factors that affect pregnancy success, and this can be done using the “Equation of Reproduction.” The equation looks at 4 main topic areas: 1) Percentage of animals detected in standing estrus and inseminated, 2) Inseminator efficiency, 3) Fertility level of the herd, and 4) Fertility level of the semen. We will utilize these four main areas in this paper to examine the keys to a successful synchronization and AI program.