Michael L. Looper, DBSFRC, USDA-ARS, 6883 South State Hwy 23, Booneville, AR 72927
Cattle grazing endophyte-infected tall fescue (EI-TF) generally exhibit a stressful multifaceted disease syndrome called fescue toxicosis. Economic losses from animal consumption of EI-TF in the U.S. exceed $600 million annually. Although not a comprehensive list, a few of the novel research approaches that may help alleviate EI-TF-associated stress in cattle with interesting preliminary data are outlined here. Extensive research has been conducted on removal of cattle from EI-TF for a certain amount of time (referred to as ‘recovery’) to alleviate the effects of EI-TF during the warm months or before transport. Implementation of novel technologies such as doppler ultrasonography in recovery studies to determine blood flow in cattle consuming EI-TF shows extreme promise to further our understanding of the physiological mechanisms of fescue toxicosis. Numerous pharmacological compounds to minimize stress related to EI-TF have been investigated with inconsistent results. However, domperidone, a dopamine receptor blocker, has been effective in alleviating some of the signs/symptoms of fescue toxicosis in horses and cattle. Research efforts are now investigating the impact of EI-TF on the fertility of the bull since the fertility of one bull will impact several cows during the breeding season. Use of traditional selection techniques is slow, usually occurring over several years for individual animals. Current research efforts are now focused on genetic and(or) physiological markers that can accelerate the selection of cattle that are more productive on EI-TF. How polymorphisms in the prolactin gene enhancer region and heat shock protein gene in cattle grazing EI-TF are related to profitability is being investigated. Several innovative techniques and technologies seek alternative solutions to the endophyte problem. An increased understanding of animal responses to EI-TF forages will be the basis of new and(or) improved best management practices for cost-effective beef production in the U.S.