Producers using artificial insemination on cows or heifers often might need to transport the cattle to summer grazing following AI service. Researchers at South Dakota State University urge care, however, noting that moving bred females at the wrong time can negatively affect reproduction. Sarah Fields, a graduate research assistant, and SDSU beef reproduction and management specialist George Perry, PhD, say shipping cows between days five and 42 post-breeding can be detrimental to embryo survival and cause around a 10 percent decrease in pregnancy rates. Producers, they conclude, should plan on transporting cattle before the breeding season or immediately after insemination. Shipping within the first four days after insemination is best, they note. By 45 days after breeding, the embryo is well established and less susceptible to the changes resulting from stress. Shipping at this point is less risky but not entirely safe. Research has shown that shipping cattle 45 to 60 days after insemination can result in 6 percent of embryos being lost. At any time, Fields and Perry advise producers to minimize stress during shipping. Do not overcrowd trailers and handle cattle as gently and calmly as possible.