Developing Synch protocols had been repetitions of trails and errors. Due to physiological difference between mature cows and yearling heifers, experiments needed be conducted separately. Scientists and college students had contributed a lot in the history (including myself??). Eventually protocols were introduced to semen industry and then at ranches. Following protocols have been proven to be efficient and practical to conduct at ranch level with optimum conception rates. Although it may seem too many to choose, I can recommend what works for your operations and budgets. I have contacts to purchase these drugs and hormones from. Here are links for each (abbr.): CIDR, MGA, PGF, and GnRH. We will discuss in advance (please! one-week notice is not enough!).