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Evolution and adoption of artificial insemination (A.I.) in the U.S
Some of the first published reports on swine A.I. in the U.S. date back to the early 1960s. At this time, 8.2 million sows were kept on mostly outdoor operations and were one component of diversified farms. Use of A.I. was sporadic. Currently, there are 5.8 million sows that are housed in specialized indoor production facilities and over 90% are bred artificially. The objective of this presentation is to review key events that led to the implementation of A.I. by the U.S. swine industry. In the late 1960s spiral-tipped Melrose catheters were introduced by scientists from universities in Missouri and Illinois upon their return from sabbaticals in Europe. This design simplified insemination; decreased sperm losses; and allowed researchers to focus on determining optimal insemination doses. During the 1970s and 1980s much of the work was devoted to the evaluation of extenders that could maintain both the viability and fertility of initially frozen and later fresh semen. Beltsville Thawing Solution was developed during this period by scientists working at the USDA Animal Reproduction Laboratory in Beltsville, MD and still is one of the most popular and effective porcine semen extenders. It was also during the 1980s when the inaugural meetings of the International Conference on Pig Reproduction and the International Conference on Boar Semen Preservation were held. Both continue to meet every 4 years and have contributed significantly to the growth of A.I. by providing forums for scientific exchange and by fostering international collaborations. During the late 1980s and through most of 1990s, consolidation and specialization within the commercial sector resulted in the growth of large, specialized sow farms and major pork processors adopted carcass-merit buying programs. These structural changes within the industry gave A.I. distinct economic advantages over natural service by reducing production costs and increasing the value of market animals. It has been estimated that the proportion of sows bred artificially in the U.S. increased from about 10% in the late 1980s to at least 85% by 2000. During the past 15 years, improvements have been made in most A.I. technologies including freezing semen. Identification of putative fertility markers and development of transcervical insemination techniques are two notable ones that hold potential to further transform how swine A.I. is routinely done on U.S. farms.
Keywords: U.S., swine, A.I.