Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Abstract

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6-week-old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.62), meat-and-bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat-and-bone meal and meat meal, highlighting significant batch-to-batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients.

The Effects of Tannins in Monogastric Animals with Special Reference to Alternative Feed Ingredients

“…In monogastric animals, the main effects of tannins are related to their protein-binding capacity and reduction in protein, starch, and energy digestibility [ 76 , 77 ]. According to [ 10 , 78 ], dry matter intake, bodyweight, feed efficiency and nutrient digestibility were reduced when chickens were fed diets with tannins, whilst Ebrahim et al [ 71 ] reported a decrease in body weight gain and feed intake. However, [ 72 , 75 ] reported no effects on growth performance and on egg weight, cell thickness or yolk color of layers.…”

Feeding Value of Lupins, Field Peas, Faba Beans and Chickpeas for Poultry: An Overview

“…Chickpeas is a good source of lysine, but deficient in methionine and cysteine. A tryptophan content of 1.8 g/kg (as received basis) was reported in chickpeas [140]. As suggested by Chiaiese et al [147], the use of transgenic techniques would help overcome the deficiency of these limited AAs.…”

Heat-processed bovine blood–rumen digesta meal and vegetable oil concentrate as partial replacement for soybean meal in broiler finisher diet

“…Although diets were supplemented with vitamin premix, possible additional vitamin B coming from RD might have been favourable for birds fed the test diets. Blood meal has a high digestibility coefficient of tryptophan, the third limiting amino acid in broilers (Ravindran et al 2006). Tryptophan stimulates growth and protein accretion through regulation of metabolic pathways (Wu 2013;Qaid and Al-Garadi 2021).…”