The modification of poultry by-product meal for use in hybrid striped bass Morone chrysops X M-saxatilis diets

A pair of experiments were performed to assess amino acid supplementation of pet food grade poultry by-product meal for utilization as the sole protein source for hybrid striped bass Morone chrysops X M. saxatilis. The first experiment determined the available amino acids from menhaden fishmeal and poultry by-product meal for hybrid striped bass. The second experiment determined the efficacy of supplementing poultry by-product meal with amino acids based on an ideal amino acid profile of hybrid striped bass muscle. The positive control diet contained 40% digestible protein solely from menhaden fishmeal and the negative control diet contained 40% digestible protein solely from pet food grade poultry by-product meal. The negative control diet was additively supplemented with lysine, methionine, threonine, and leucine at 1.16, 0.57, 0.31 and 0.47% of the diet, respectively. Lysine supplementation alone did not improve fish performance based on any measured response. Moreover, the negative control diet and the lysine supplemented diet had lower weight gain and feed efficiency than the positive control diet. Supplementation of the diet containing pet food grade poultry by-product with lysine and methionine; lysine, methionine, and threonine; or lysine, methionine, threonine, and leucine improved weight gain and feed efficiency above that of the negative control diet. The diet containing poultry by-product supplemented with lysine, methionine, and threonine produced weight gains statistically indistinguishable from those of the positive control diet. Protein and energy retention efficiencies also improved with supplementation of at least lysine and methionine and were statistically indistinguishable from those observed in fish fed the positive control diet. Supplementation with lysine and methionine reduced the hepatosomatic index to levels similar to those found in fish fed the menhaden fishmeal diet. Intraperitoneal fat levels were similar among treatments (6.1-6.6%) with the exception that fish fed the diet supplemented with lysine, methionine, and threonine exhibited lower (5.5%) fat levels. Supplementing the poultry by-product meal diet with only lysine and methionine increased muscle ratio to levels equivalent to those found in fish fed the positive control (fishmeal) diet. In conclusion, amino acid supplementation of pet food grade poultry by-product meal can be used to replace fishmeal in diets for hybrid striped bass without a reduction in fish performance.