2011 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to identify mechanisms and develop tools and methods to improve reproductive and growth efficiency of catfish. 1b.Approach (from AD-416) Continued collaborative research will be conducted to identify mechanisms for targeted enhancement of catfish reproduction and growth in order to fulfill the unit’s data collection, publication, and catfish improvement efforts. 3.Progress Report Xenotransplantation of testicular germ cells from blue catfish to otherwise sterile channel catfish provides a unique alternative to current production methods for hybrid catfish. ARS and the cooperator conducted collaborative research on the xenotransplantation of spermatogonial germ cells in catfish. Blue catfish testicular cells were isolated and injected into channel catfish cohorts, which are currently being grown to maturity. Means of verifying success prior to reproduction continue to be evaluated. Several genetic markers have been tested that will allow for the early determination of transplantation success. As fish mature, these markers will be utilized. If successful, the fish and technology can be transferred to the hybrid catfish industry. Evaluation of the regulatory aspects of feed intake is important to understanding fish growth, as growth in catfish is highly correlated to feed intake. ARS and the cooperator conducted collaborative research in this area. Several suspected neuroendocrine regulators of feed intake have been identified in the catfish genome and assays developed to assess their functional expression during different nutritional states. Further research is planned to evaluate the direct effects of exogenous neuropeptides on feeding behavior and metabolism. This research contributes to a better understanding of the regulation of fish growth and may lead to improved management or feed formulations that will increase fish feed efficiency and profitability for the farmer. ADODR used site visit, email and telephone conferences to monitor activities of the project.