BIF-Proceedings-Final-flip

72 2018 BIF Research Symposium and Convention • Proceeding Papers Introduction The constant increase in the world’s population goes by hand-in-hand with a sustainable increase in the global demand for quality food. Additionally, the increase in human population from developed countries has been historically associated with increases in food consumption per capita, and increased amounts of livestock products in the diet. This scenario holds true for developing countries today, and leads to the need for increased production and/or efficiency from livestock systems. In the United States, the most important livestock industries correspond to cattle production, with large national economic impacts. Furthermore, the United States is the largest producer of beef products in the world, supplying a variety of products for domestic and external markets. Considering the expected increases of global demand for livestock products, beef production in the United States is under constant need for increasing production system efficiency. Among the options to increase the efficiency of beef production systems is crossbreeding between Bos taurus indicus (Bi) and Bos taurus taurus (Bt) breeds. This type of cross makes it possible to utilize greater heterosis for economically relevant traits in beef cattle, in addition to advantages provided by Bi breeds, such as higher resistance to disease and parasites, and greater adaptation to tropical and subtropical climates. As a consequence, use of Brahman (Bi breed) and Brahman x Bt crosses has been key for cattle operations in the southern and southeastern regions of the United States, where the predominant subtropical climate could lead to the reduction in efficiency of purebred Bt or crosses between two or more Bt breeds. However, several authors have reported differences in growth-related traits between Bi x Bt F1 reciprocal crosses, particularly where Bi-sired calves express higher birth weights, and a tendency to have higher weaning weights and yearling weights. Moreover, this pattern has also been observed among other Bi-Bt crosses when the sire had a higher amount of Bi influence in comparison to the amount of Bi in dam. Additionally, sexual dimorphism has also been reported between the reciprocal F1 and backcrosses, where the difference in weights between male and female calves is Parent-of-origin Effects on Growth Related Traits in Bos taurus indicus x Bos taurus taurus Reciprocal Crosses Jose S. Delgadillo Liberona much greater in Bi-sired calves, as well as when the sire has a higher contribution of Bi to its genetic composition in relation to the dam. Parent-of-origin effects, through genomic imprinting, have been proposed as a potential mechanism that could be explaining this peculiar phenomenon. However, further research is needed to fully uncover the genomic and molecular bases behind these reciprocal crosses differences. Review of literature World demand for livestock products World population is under constant growth, as is world food demand and production. So far the growth rate of global food production has been faster than the rate of population growth, which should make possible to satisfy the food consumption needs of nearly everyone. However this has not being a reality because of many different factors, with poverty probably the most important cause. The Food and Agriculture Organization of the United Nations (FAO) has estimated that the human population could reach 9.15 billion by the year 2050 (Alexandratos and Bruinsma, 2012). This implies a challenge for agriculture in order to keep growing food production at rates that could satisfy the global increases in food demand. Additionally, the increase in population and wealth in developed countries has been associated with increases in per capita food consumption and increased consumption of livestock products. This pattern can also be observed in developing countries, but the increase in consumption of livestock products will probably not be as strong as what occurred in western developed countries (Alexandratos and Bruinsma, 2012). Nevertheless, the estimated increase in population and in global demand for livestock products will produce a major impact in agriculture world-wide. Cattle production in the United States Among livestock products, cattle production represents one of the most important industries in the United States, ranking first in forecasted total cash receipts (USDA, 2016). Moreover, the United States’ cattle industries correspond to the largest producer of beef in the world, with a variety of products for both domestic and external markets (USDA, 2018). ~ 2018 Baker/Cundiff Award Recipient ~