Novel production of Atlantic salmon ( Salmo salar) protein based on combined replacement of fish meal and fish oil with plant meal and vegetable oil blends

Abstract

The aim of the present study was to combine maximum replacement of fish meal and fish oil with plant ingredients in feed for Atlantic salmon, in order to gain a sound and sustainable net fish protein production. The design implied that all known nutrient requirements should be met. Atlantic salmon smolts with an initial weight of 0.3 kg were fed in triplicate either a fully marine control diet or one of three plant based diets through the seawater production phase for 12 months, until final weight of approximately 4 kg. In a maximum plant based diet, 80% of the fish meal was replaced with a mixture of plant protein ingredients and krill meal, while 70% the fish oil was replaced with a mixture of vegetable oils. Two intermediate replacement diets contained either one half of this fish meal replacement level and maximum fish oil replacement, or one half replacement level of fish oil and maximum fish meal replacement. Fish performance was assessed by measuring mortality, feed intake, growth, nutrient digestibility and nutrient utilisation. Specific growth rate was significantly lower in the combined high replacement group compared to the other experimental groups, both for the first 3-month period (12%) and for the complete 12 months (9%) of feeding. The final fish weights were 17% lower in the combined high replacement group and 9% lower in the high plant protein and intermediate vegetable oil group, compared to the marine control and the intermediate plant protein group. Significantly reduced feed intake during the first period and slightly reduced digestibility of 16:0 and starch were identified as possible causes for growth depression, since minor differences in protein or lipid digestibility, feed conversion ratio, and protein and lipid retention were observed. The maximum fish meal and fish oil replacement represented a net production of fish protein, with 2 kg salmon protein produced per kg fish meal protein fed. This being four-fold more efficient usage of fish meal in the 80% plant protein diets compared to the 100% fish raw material diet.