Progress 01/01/11 to 12/31/11
OUTPUTS: Data collected from the six studies involving factorial experiments were subjected to two-way ANOVA, and differences between means were determined by Duncan's New Multiple Range Test. Treatment main and interaction effects were considered significant at P<0.05. At the end of each feeding trial, the following parameters were determined Percent weight gain = [(final wt - initial wt)/initial wt] x100; Feed efficiency = wet wt gain/dry feed fed; Mean feed consumption = total feed consumed (dry wt)/# of fish; Protein efficiency ratio = live wt gain/protein intake; Protein productive value = [(final protein content−initial protein content)/protein consumed]; Energy productive value = [(final energy content−initial energy content)/energy consumed]; Lipid efficiency ratio= live wt gain/lipid intake; Condition factor = wt/length3; and Specific growth rate = [(ln final wt - ln initial wt)/# of days] x 100. Also, mitochondrial oxygen consumption rate, mitochondrial complex enzymatic activities, and mitochondrial gene expression levels were determined for liver, muscle and intestine. Results from the project will be presented at Aquaculture America 2012, Las Vegas, Nevada. Feb 20 - Mar 2, 2012. Results from the project had been presented at the Annual International Conference and Exposition of the World Aquaculture Society, Natal Brazil. June 6-10, 2011; 1890 institutions of Association of Research Directors 15th and 16th Biennial Research Symposium at Atlanta, Georgia, Mar 28-Apr 1, 2009 and Apr 9- 13, 2011, respectively. The project impacted 23 students through participation in directed student research. The feeding and analyses of data were incorporated into classroom teaching, especially for two courses (Principles of Aquaculture and Biology of Fishes) taught at the WVSU. Project resources were to purchase equipment such as ABI 7300 rt-PCR System, thermal cycler and refrigerated centrifuge used in teaching and research currently used for the training of undergraduate and graduate students in molecular biology, especially genomics and nutrigenomics. The results from the project provide some evidence to the association of mitochondrial function with the phenotypic expression of feed efficiency in rainbow trout and channel catfish. Results further showed that mitochondrial respiratory chain activity, gene expression, and protein oxidation are linked to nutrient utilization efficiencies in rainbow trout and channel catfish identified as having low or high feed efficiency. The research served as a platform for hands-on training for graduate and undergraduate students in WVSU in genomic-enabled nutritional research to solving aquaculture related problems. Moreover, this project impacted several students through participation in directed student research and the integration of classroom teaching to performing experiments associated with the project. The research laid the foundation for some of minorities and/or undergraduates/graduates that participated in this project to pursue their graduate education in aquaculture and/or biotechnology having worked side-by-side with multidisciplinary research scientists with different areas of expertise. PARTICIPANTS: Project Director designed, implemented, supervised a research associate, graduate and undergraduate student, and performed data analyses. Rainbow trout for studies 1 and 2 feeding trials were generously supplied by the collaborators (Drs. Greg Weber, Caird Rexroad, Beth Cleveland) at the USDA-ARS National Center for Cool and Cold Water Aquaculture. Feed formulation and manufacture was performed by Dr. Ann Gannam of U.S. Fish and Wildlife Service, Abernathy Fish Technology Center. A research associate, a research technician, and two students participated in the study and their duties included feeding, sampling, collecting and analyzing data. TARGET AUDIENCES: The target audience includes fish farmers, fish feed industries and researchers that are involved in selective breeding of aquaculture species. One graduate and an undergraduate student earned credits hours in directed student research. The data collection and analyses were utilized as teaching resource for the students who participated in the experiment as part of their directed student research and acquired credit units toward their major and thesis. PROJECT MODIFICATIONS: The feeding trials for both studies were terminated after 90 days instead of 112 days because of the failure of the water cooling system.
Findings from this research for the first time in rainbow trout and channel catfish, demonstrated a strong relationship between diet, strain types and mitochondrial function. Furthermore, results showed variations in the expression levels of some mitochondrial encoded genes and mitochondrial complex enzyme activities in different tissues of rainbow trout and the family with high feed efficiency (FE) and better nutrient utilization had higher numerical values for respiratory chain enzyme activities, down-regulation of hepatic complex I ND1 gene and its up-regulation in the intestine and muscle compared to the low FE family. Data from the research showed that in rainbow trout families with high FE, diet containing 42% crude protein (CP)/20% fat was significantly better than those containing either 42% CP/10% fat or 42% CP/30% fat in terms of growth performance characteristics. Thus, the popular belief that high fat diets (above 20% fat) are necessary for efficient production of fish is not supported by this study. Another aspects of the findings in channel catfish showed that diet containing 32% CP from all-plant protein sources is as good as diets (28% and 32% CP) containing fishmeal for optimum growth and improved FE. However, the mitochondrial function, especially the mitochondrial gene expression levels were significantly down-regulated in fish fed diet containing 32% CP from all-plant protein sources in the liver and intestine. Overall, our data indicate that genetic factor plays a role in rainbow trout and channel catfish production and fish selected for improved growth and high FE when fed practical diet exhibited significant genotype x diet interaction. Thus, if "fine-tuning" of dietary formulations is to be considered in the future, selection strategies that account for that interaction should be considered. The observed changes in some of the selected mitochondrial genes in relation to growth and nutrient utilization efficiencies could serve as marker(s) in breeding selection for genetic improvement of rainbow trout and channel catfish and possibly other aquaculture species.
- Eya, J.C., Ashame, M.F. and Pomeroy, C.F. 2011: Association of mitochondrial function with feed efficiency in rainbow trout: Diets and family effects. Aquaculture 321(1-2):71-84.
- Eya, J.C., Ashame, M.F., Pomeroy, C.F., Manning, B.B. and Brian, B.C. 2011. Genetic variation in feed consumption, growth, nutrient utilization efficiency and mitochondrial function within a farmed population of channel catfish (Ictalurus punctatus). Aquaculture (Pending).
- Eya, J.C., Ashame, M.F. Pomeroy, C.F, and Gannam, A. L. 2012. Genetic relationships of growth, feed efficiency and mitochondrial function in rainbow trout (Oncorhynchus mykiss) fed diets differing in dietary lipid levels (Manuscript in preparation).
- Eya, J.C., Ashame, M.F., Manning, B.B. and Brian, B.C. 2012. Effect of strain and diet on growth performance characteristics and relative expression of genes coding for electron transport chain in channel catfish (Manuscript in preparation).