Digestibility of amino acids in Indian mustard protein concentrate and Indian mustard meal compared to that of a soy protein concentrate in rainbow trout and Atlantic salmon

Abstract

Digestibility trials were carried out to determine the apparent digestibility of amino acids (AA) of two novel plant protein ingredients, Indian mustard protein concentrate—(IMC, 62% crude protein) and Indian mustard meal (IMM, 42% crude protein) produced through a low temperature process, and a commercially available soy protein concentrate (SPC, 57% crude protein) in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). The apparent digestibility coefficient (ADC) of crude protein (CP) from IMC was 90% and 97% for trout and salmon, respectively. The ADCs of CP from IMM and SPC were also very high (>95%) for both species. The ADCs of lysine (95%), isoleucine (91%), leucine (86%) and phenylalanine (90%) from IMC were slightly lower (P<0.05) than those from IMM and SPC for rainbow trout. Conversely, for Atlantic salmon, ADCs of isoleucine from both IMC (94%) and IMM (92%) were lower than those from SPC (97%). Despite small differences, the ADC of most AA in these novel products were very good (>90%). These results suggest that low glucosinolate Indian mustard protein concentrate and Indian mustard meal are ingredients of high nutritive value. However, it is hypothesized that the high phytic acid level in the Indian mustard protein concentrate may negatively affect the digestibility of CP and certain amino acids when used at high level in the feed of fast growing fish.