ARS | Publication request: Do small efficient fish grow into large efficient fish?

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: September 15, 2006
Publication Date: February 26, 2007
Citation: Silverstein, J., Pomeroy, S., Blemings, K., Casten, M. 2007. Do small efficient fish grow into large efficient fish?. Meeting Abstract.

Technical Abstract: Feed efficiency is an important trait for cultured fish; more efficient animals not only grow on less feed, but they produce less waste as well. Nevertheless, because individual feed intake is hard to accurately estimate, feed efficiency is a difficult trait to measure, and many factors contribute to variation in feed efficiency. Variation in routine activity levels between fish, differences in partitioning of consumed energy into protein and fat storage, and differences in digestion may all contribute to variation in feed efficiency. At the National Center for Cool and Cold Water Aquaculture we are interested in developing more efficient rainbow trout. The first step has been measuring efficiency in family groups to determine whether feed efficiency has a genetic component. We have identified significant family differences for efficiency. When tracking high and low efficiency families for further metabolic studies we found that the trait of feed efficiency was frequently not stable and that feed efficiencies measured over multiple intervals were often uncorrelated (Figure 1). This has led us to focus on measuring feed efficiency in rainbow trout around harvest size, the time when the greatest portion of feed is consumed. We have measured the growth of 175 fish distributed in 57 families over five months and their daily intake on five separate occasions. The heritability of growth over the 5 months was moderately high near 0.40, and the heritability of daily feed intake was considerably lower at 0.10-0.15. The relationships of feed intake and growth estimates within the five month period will be presented.