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Keywords:

  • amino acid availability;
  • Morone;
  • sunshine bass

Abstract

A study was conducted with market-size (867 g) hybrid striped bass to determine the nutrient digestibility and apparent amino acid availability of six common feedstuffs. The animal-protein feedstuffs tested were menhaden fish meal (MEN), anchovy fish meal (ANCH), pet-food grade poultry by-product meal (PBM-pet), and feed-grade poultry by-product meal (PBM-feed), while the plant-protein feedstuffs were dehulled solvent extracted soybean meal (SBM) and distiller’s dried grains with solubles (DDGS). Test diets consisted of a 70 : 30 mixture of reference diet to test ingredient with chromic oxide (10 g kg−1%) as the inert marker. Diets were randomly assigned to triplicate tanks of fish that were fed their respective diets for 7 days prior to fecal collection by stripping. Two feeding trials were conducted sequentially to determine the digestibility of the six test ingredients. In trial 1, the three ingredients evaluated were MEN, PBM-feed, and PBM-pet. In trial 2, the three ingredients evaluated were ANCH, SBM, and DDGS. Apparent digestibility coefficients of protein (ADC-CP) were significantly (< 0.05) different among test ingredients in trial 1 as protein digestibility of MEN (86%) was significantly higher (< 0.05) than that of PBM-feed (75%), but was not significantly different from that of PBM-pet (78%). Protein digestibilities in trial 2 were not significantly different among test ingredients and averaged 76% for ANCH, SBM, and DDGS. Some apparent amino acid availability coefficients differed among feedstuffs for both trial 1 and trial 2. MEN provided higher amino acid availabilities for alanine, aspartic acid, glutamic acid, lysine, valine, and tryptophan (99%, 98%, 94%, 96%, 99%, and 108%, respectively) when compared to PBM-feed (73%, 50%, 69%, 80%, 77%, and 91%, respectively) and PBM-pet (79%, 66%, 81%, 81%, 78%, and 99% respectively). Glycine, histidine, leucine, and proline availabilities in MEN (95%, 96%, 100%, and 98%, respectively) were significantly (< 0.05) higher than those of PBM-feed (64%, 82%, 82%, and 57%, respectively), but were not significantly different from PBM-pet (85%, 92%, 89%, and 80%, respectively). For trial 2, apparent amino acid availabilities for cystine, isoleucine, lysine, and tyrosine were significantly higher (< 0.05) among treatments fed SBM (100%, 87%, 93%, and 97%, respectively) and ANCH (37%, 95%, 92%, and 84%, respectively) compared to treatments fed DDGS (−13%, 52%, 62% and 62%, respectively). Overall, amino acid availability in SBM and the two PBM’s appear comparable to MEN and ANCH and corroborate their high value as potential replacements for fish meal in sunshine bass diets. However, DDGS provided the lowest availabilities for several amino acids and should be used with caution.