VARIANCE IN THE PHYSIOLOGICAL RESPONSES FROM THREE DIFFERENT STRAINS OF RAINBOW TROUT

Our program has been selecting rainbow trout for enhanced utilization of  plant-based feeds for nine generations. As this strain has been evaluated we routinely compare this selected strain against other domesticated lines of rainbow trout under vaired experimental conditions.  This presentation will report in greater detail the physiological and nutritional changes documented for the ARS select line of trout and two other commercial lines.  In nutritional studies our lab has verified that  differences between the ARS selected fish and commercial control lines exist in nutrient uptake and retention, specifically in regards to amino acid transportation and metabolite levels detected in specific tissues (Fig 1). Very significant d ifferences in growth  was found  between the strains  on both the fishmeal and plantmeal based feeds but it was much greater when comparing between the lines when  reared  on the plantmeal feed. Furthermore, on the plantmeal feed the detection and development of enteritis was  only found in the control lines  when  the fish were analyzed from two to eight months on the feed.  Histochemical evaluation of the  ARS select line versus control lines show ed  significant cellular and morphological differences.  Significant differences were also found between the strains for resistance to specific bacterial and viral pathogens.