Short-term feeding cessation prior to harvest does not affect fillet yield in rainbow trout

Authors: Welker, Thomas; Overturf, Kenneth - Ken; Barrows, Frederic; Abernathy, Jason; SNYDER, SCOTT - Clear Springs Foods, Inc; LAPATRA, SCOTT - Clear Springs Foods, Inc

Submitted to: Annals of Aquaculture and Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2015
Publication Date: 10/4/2015
Citation: Welker, T.L., Overturf, K.E., Barrows, F., Abernathy, J.W., Snyder, S.G., Lapatra, S.E. 2015. Short-term feeding cessation prior to harvest does not affect fillet yield in rainbow trout. Annals of Aquaculture and Research. 2(2):1011.

Interpretive Summary: Feed costs account for approximately 60% of the operating expenses on freshwater rainbow trout farms. The current practice in the USA is to feed trout until the day prior to harvest on commercial farms. However, research shows that growth is largely unaffected during periods of reduced feed intake or starvation for up to 30 days or longer in salmonids, including rainbow trout. Cessation of feeding even a few days prior to harvest has the potential to produce large economic benefits to farmers. To investigate this, we withheld feed from market size rainbow trout (~500 g or 1.1 lbs.) for 1, 2, 3, 4, and 8 days prior to harvest and evaluated the effects on growth (body weight and fillet yield; % of whole body wet weight). This study was conducted in a research tank system on a commercial trout farm under conditions that were replicated as closely as possible. Weight gain and fillet yield were not negatively affected by short-term feeding cessation for as long as 8 days. Because feed is the primary cost in commercial trout operations, cessation of feeding 1 week prior to harvest has the potential to provide a significant reduction in feed costs for both large and small rainbow trout operations.

Technical Abstract: Current practice in commercial, freshwater rainbow trout operations in the USA is to feed until the day prior to harvest. However, from what is known about fish growth and metabolism during periods of starvation, this may not be the best economic practice, since growth and macronutrient deposition are affected little during short-term starvation. Therefore, cessation of feeding even a few days before harvest has the potential to produce substantial economic savings to trout growers with little or no impact on yield. To investigate this, we withheld feed from market size rainbow trout (~500 g) for 1, 2, 3, 4, and 8 days prior to harvest and evaluated the effects on body weight, fillet yield (% of whole body wet weight), and whole body proximate composition. This study was conducted in a research tank system in which 3rd use water (2 raceway passes), and commercial culture conditions were replicated as closely as possible. Weight gain, fillet yield, and proximate composition were not significantly affected by short-term feeding cessation. Because feed is the primary cost in commercial trout operations, cessation of feeding 1 week prior to harvest has the potential to provide a significant reduction in feed costs for both large and small rainbow trout operations.