IMPROVING SUSTAINABILITY OF RAINBOW TROUT PRODUCTION BY INTEGRATED DEVELOPMENT OF IMPROVED GRAINS, FEEDS, AND TROUT
Location: Small Grains and Potato Germplasm Research
Title: Severity of soybean meal induced distal intestinal inflammation, enterocyte proliferation rate, and fatty acid binding protein (Fabp2) staining differ between strains of rainbow trout (Oncorhynchus mykiss)
Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 2012
Publication Date: August 30, 2012
Citation: Venold, F., Penn, M., Krogdahl, A., Overturf, K.E. 2012. Severity of soybean meal induced distal intestinal inflammation, enterocyte proliferation rate, and fatty acid binding protein (Fabp2) staining differ between strains of rainbow trout (Oncorhynchus mykiss). Aquaculture. 364-365:281-292.
Interpretive Summary: Aquaculture production is expanding significantly around the world. One of the major impediments to both current and developing aquaculture production is the availability of sustainable sources of feed. Sustainable feeds have been developed but growth on these feeds is much lower than growth on traditional fishmeal based diets. A strain of rainbow trout was developed by the USDA-ARS in Hagerman, Idaho by selecting for growth and utilization of a sustainable plant-based feed. The ARS is currently examining the physiological changes that have occurred in the selected line that allows them to eat and utilize plant-based feeds more effectively. In this experiment it was found that the intestinal tract of selected rainbow trout showed an increased tolerance for the use of a plant-based feed when compared to unselected trout.
Complete replacement of fishmeal in feeds for carnivorous fishes often causes reduced growth and can negatively affect health. Salmonids fed diets containing full fat or defatted soybean meal develop dose dependent inflammation in the distal intestine (DI). Little is known about the sensitivity of different strains of rainbow trout to the effects of plant based diets. The current study investigated the response of a non-selected (NS) and selected (SE) strain of rainbow trout to a fishmeal free, plant based diet containing a high level of soybean meal. Fish from both strains were each divided into two groups and fed either a fish meal based control diet (FM) or an all plant meal diet (PM) containing 19% soybean meal, resulting in four treatments: FM-NS, FM-SE, PM-NS, and PM-SE. Tissue samples of the DI were collected after three months of feeding for histological (hematoxylin and eosin) and immunohistochemical (proliferating cell nuclear antigen, PCNA, and fatty acid binding protein 2, FABP2) analyses. Fish from the PM-NS treatment showed typical signs of DI inflammation, while the PM-SE did not and appeared equivalent to FM fed treatments. Moreover, the PM-NS fish displayed greater enterocyte PCNA staining indicating increased numbers of proliferating cells, and lower enterocyte Fabp2 staining compared to all other treatments. No differences were observed between FM-SE, FM-NS and PM-SE treatments. Results of the current work indicate that the sensitivity to dietary soybean meal varies between rainbow trout strains, and suggests that improved tolerance to dietary soy may be achieved by selective breeding.