Apparent Digestibility Coefficients Of Crude Protein Research Articles

Digestibility of macronutrients, energy and amino acids, absorption of elements and absence of intestinal enteritis in Atlantic salmon, Salmo salar, fed diets with wheat gluten

Apparent digestibility coefficients (ADCs) of macronutrients and energy, and apparent absorption coefficients (AACs) of amino acids and elements were assessed in an experiment with 0.9 kg Atlantic salmon reared in saltwater tanks. Duplicate groups of fish were fed five diets, where 0, 6.25, 12.5, 25 and 50% of crude protein (CP) from fish meal (FM) was replaced with CP from wheat gluten (WG). In Experiment 2, triplicate groups of 0.9 kg salmon were fed a FM diet, a diet with 15% of CP from FM replaced with extracted, toasted soybean meal (SBM), and a diet with 35% of CP from WG, for 18 weeks. Experiment 2 was designed to determine whether WG caused pathological changes in the intestinal epithelium, and if a diet with 35% of CP from WG could support rapid growth. There was a trend toward increased ADC of fat and energy in the diets with WG, and the diet with 25% WG was ranked significantly higher than the FM control. The ADC of CP and AACs of all amino acids except alanine and lysine increased significantly with increasing proportion of dietary protein from WG, and the results indicate that absorption of individual amino acids from WG was between 94% and 100%. WG is low in lysine, but the results indicate that the requirement for lysine was nearly met and the requirement for other essential amino acids was met even with the highest WG inclusion level, due to high dietary protein concentration and the supplementary amino acid profile of FM. There was no reduced absorption of Ca, P or Mg in the salmon fed diets with WG. The absorption of Zn was higher in all the diets with WG than in the FM diet. The fish doubled their weight during Experiment 2, and there were no significant differences in growth among dietary treatments in salmon fed the WG, FM or SBM diets. No indication of intestinal pathology was seen in the salmon fed the FM or WG diets, while 60% of the examined fish fed SBM had SBM-induced changes in the mucosa of the posterior intestine.

Apparent digestibility of selected ingredients in red drum ( Sciaenops ocellatus) diets

Production of cultured red drum requires use of formulated diets for grow-out to marketable size. However, insufficient information is available regarding the nutrition of this species to make least-cost feed formulation practical. Knowledge of the digestibility of ingredients used in red drum diets could facilitate least-cost formulation and reduce feed costs. The objective of this study was to determine apparent digestibility of dry matter, crude protein, and energy in blood meal, corn grain, cottonseed meal, grain sorghum, meat and bone meal, menhaden fish meal, rice bran, soybean meal, and wheat middlings in formulated red drum diets. Digestibility coefficients were determined using a reference diet and test diets that contained 70% of the reference diet mixture and 30% test ingredient. All diets contained 1% chromic oxide as a digestibility indicator. Fecal samples were manually stripped from anesthetized fish to prevent contact with water. Apparent digestibility coefficients for dry matter, crude protein, and energy in the reference and test diets were determined, and digestibility coefficients for the test ingredients were calculated based on differences in the digestibility of test diets relative to the reference diet. Apparent crude protein digestibility coefficients ranged from 74 to 100% for all feedstuffs tested, indicating that red drum utilized dietary protein efficiently regardless of source. Protein digestibility was highest in feedstuffs with high protein content (> 60%) and low fiber content (< 2%). Apparent energy digestibility was relatively low for animal products (54–60%) and lower for plant products (12–52%). Dry matter digestibility varied more among ingredients of plant origin (18–68%) than among those of animal origin (65–77%). Apparent digestibility of dry matter and energy was positively influenced by protein and lipid content of the ingredient and negatively influenced by crude fiber content. Digestibility of starch appeared to vary widely among plant products.

Protein Digestibility Coefficients for Yearling Channel Catfish Fed High Protein Feedstuffs

Abstract Yearling (1 +) channel catfish (Ictalurus punctatus) were held in a regulated environment and fed high protein feedstuffs to determine apparent crude protein digestibility coefficients (ACPD). ACPD was determined by feeding semi-purified diets containing a sufficient non-protein energy source and substituting the test feedstuff at an isonitrogenous level. Feedstuffs tested were corn gluten meal, peanut meal, poultry by-product meal, soybean meal, menhaden fish meal, blood meal, and meat and bone meal. ACPD values ranged from 92% for corn gluten meal to 65% for poultry by-product meal. Mean ACPD from plant sources was higher than the mean ACPD from animal sources but may be an artifact of the feedstuffs tested.