Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract only
Publication Acceptance Date: 9/15/2007
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Fish meal has been a primary protein source in trout feeds and any changes that can reduce fish meal levels and total costs are beneficial. Replacing fish meal with plant protein is a first step, but amino acid content of plant based diets can be limiting. Amino acids are needed for many metabolic functions, the largest being protein accretion and metabolic fuel. Providing the proper dietary amino acid balance will reduce feed costs and nitrogenous waste output as ammonia. The “Ideal Protein” concept has been studied widely. The concept is to supply amino acids in an ideal ratio to each other to meet the needs of the animal without excess. A 2X2 factorial experiment was conducted for 12 weeks with 4 feeds. Protein level and amino acid supplementation were the main effects, with 35 and 45% intact protein from plant origin with or without supplemental lysine, methionine and threonine. The AAs were supplemented to attain levels equivalent to 45% protein from trout muscle. The 45+AA diets received 0.11 and 1.28% supplemental methionine and lysine, respectively, and the 35+AA received 0.45, 1.85, and 0.51% supplemental methionine, lysine and threonine, respectively. Effects of AA, but not protein, were observed on weight gain, FCR and FI. Interactions of protein and AA occurred for FCR and FI. Diet also affected HSI, MR, IPF. HSI was reduced with both protein and AA. IPF ratio was reduced by AA supplementation, but not protein level. Muscle ratio was affected by both protein level and AA. Whole body protein increased with AA supplementation, and significant interactions occurred. Protein retention efficiency was improved from 30 to 38% with AA supplementation for the 35% protein diets and from 28 to 31% for the 45% protein diets. In conclusion, amino acid supplementation improved fish performance and identifies potential of reducing crude dietary protein level.