High level of dietary pea protein concentrate induces enteropathy in Atlantic salmon (Salmo salar L.)

The current study investigated the effects of pea protein concentrate, soy protein concentrate and corn gluten, either singly at high inclusion, or in combination, each at lower inclusion, in diets for Atlantic salmon (Salmo salar L.). Growth performance, nutrient digestibility, intestinal brush border enzyme activity, and intestinal histology were studied in an 8-week feeding trial. Triplicate groups of Atlantic salmon (2.36kg initial weight) were kept in sea water at winter temperature. Five diets were tested, including a control diet based on fish meal (FM diet; 250gkg−1 fishmeal) and four low fishmeal (100gkg−1) diets: a diet containing 350gkg−1 pea protein concentrate (PPC diet), a diet containing 300gkg−1 soy protein concentrate (SPC diet), a diet containing 300gkg−1 corn gluten (CG diet) and a combination diet containing 130gkg−1 pea protein concentrate, 105gkg−1 soy protein concentrate and 105gkg−1 corn gluten (CMB diet). Fish fed CG and PPC diets showed lower SGR than fish fed the FM diet and there was a trend (P<0.09) towards a higher feed conversion (FCR) in the fish receiving the CG and PPC diets. Apparent fat digestibility was lower in fish fed SPC, PPC and CMB diets compared to FM. No difference in apparent crude protein digestibility was observed. Feeding the PPC diet resulted in reduced relative weight and inflammation in the distal intestine similar to those described for soy enteritis. Additionally, fish fed the PPC diet had reduced brush border enzyme activities in the distal intestine and increased trypsin activity in the digesta from the distal intestine region. In conclusion, pea protein concentrate at high inclusion was shown to induce an enteropathy in the distal intestine of Atlantic salmon and caution should be used when including it in formulated feeds for Atlantic salmon.