Physiology and Management of Pharmacologically-Controlled Breeding Programs in Beef Cows
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It has been estimated that nearly 30% of the cattle in the U.S. have some percentage of Bos indicus breeding, primarily American Brahman. Breeds and breed types with Bos indicus influence are adapted to and predominate in the southern regions of the U.S. where approximately 42% of the nation's beef cows and nearly 50% of its cow-calf producers reside.. When Brahman or Brahman-influenced cattle are crossed with English and Continental breeds, the resulting offspring exhibit wide adaptability, heterosis for important growth and carcass traits, and the capability of meeting national carcass quality targets when fed and managed appropriately. The current national focus on consistent beef quality, and the genetic strategies needed to achieve that quality, requires the use of technologies such as AI and synchronization of estrus/ovulation in order to be optimally successful. Thus, ourlong-term aimsare to develop and optimize strategies for synchronization of ovulation in Bos indicus-influenced cattle to consistently achieve TAI pregnancy rates of ≥ 50% and to determine environmental, nutritional, and managerial factors that influence the variation in pregnancy rates associated with fixed-time AI in these types of cattle.