Short-term Feeding Cessation Prior to Harvest Does Not Affect Fillet Yield in Rainbow Trout - 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 (P>0.05) by short-term feeding cessation. Because feed is the primary cost in commercial trout operations, cessation of feeding 8 days prior to harvest has the potential to provide a significant reduction in feed costs for both large and small rainbow trout operations by reducing feed use 2% annually