Growth performance, proximate and histological analysis of rainbow trout fed diets containing Camelina sativa seeds, meal (high-oil and solvent-extracted) and oil

Abstract

Two 112-day feeding trials were conducted to examine the effects of including camelina (Camelina sativa) products in rainbow trout diets. In the first experiment, 20 tanks (40L) of rainbow trout (Oncorhynchus mykiss; 2.36±0.18g, 30 fish/tank) were fed one of five diets containing solvent-extracted camelina meal (SECM) at dietary inclusion levels of 0, 50, 100, 150 or 200g/kg. Weight gain and specific growth rate (SGR) of fish fed 200g/kg SECM were significantly lower than those fed 0 and 50g/kg SECM. The protein efficiency ratio (PER) of fish fed 50g/kg SECM (2.4) was significantly higher than fish fed 0, 150 and 200g/kg SECM (all 2.1). There were no significant differences among treatments for total feed consumption or FCR, although during earlier periods of the trial, fish fed 150 and 200g/kg SECM had higher FCR than fish fed 0 and 50g/kg SECM (P<0.05). In the second experiment, 24 tanks (40L) of rainbow trout (1.0±0.1g, 30 fish/tank) were fed one of eight diets: a control diet; six diets containing full-fat camelina seed or high oil residue camelina meal (HORM), at dietary inclusion levels of 100, 200 and 300g/kg; or a diet that contained 100g/kg SECM and 151g/kg camelina oil (SECM+CO), with no added fish oil. After 112days on feed, fish fed diet containing 300g/kg camelina seed and 300g/kg HORM gained less weight than fish fed the control diet (P<0.05). Fish that consumed 300g/kg camelina seed also gained significantly less weight than fish fed 100g/kg camelina seed and 100g/kg HORM. Feed consumption was not affected by diet. FCR was higher in fish fed 300g/kg HORM than in fish fed 100g/kg camelina seed and the PER of the fish fed 300g/kg HORM was lower than that of fish fed 100g/kg camelina seed and HORM (P<0.05). There was no treatment effect on the intestinal histology of fish fed these diets (P<0.05). Fish fed up to 100g/kg SECM, camelina seed and HORM, as well as the SECM+CO diet did not perform any differently than fish fed the control diet (P>0.05). Although there were a few negative effects on performance in fish fed 200g/kg camelina seed and HORM early in the trial, this did not remain consistent for the entire trial. The maximum dietary inclusion threshold of these camelina products in juvenile rainbow trout diets is likely between 100 and 200g/kg, although further research will be required to determine more definite values. Statement of relevanceThis study determines the feed intake and growth response of rainbow trout fed camelina seed (dietary inclusion levels of 0, 100, 200 and 300g/kg), high oil residue camelina meal (dietary inclusion levels of 0, 100, 200 and 300g/kg) and solvent-extracted camelina meal (dietary inclusion levels of 0, 50, 100, 150 and 200g/kg) and a combination of 100g/kg solvent-extracted camelina meal and 151g/kg camelina oil, as well as information regarding the carcass composition and intestinal morphology of fish fed the first two ingredients. This research provides data that will enable the formulation of practical diets using these feed ingredients.