Apparent ileal digestibility of amino acids in dietary ingredients for broiler chickens

Abstract

The apparent ileal digestibility coefficients of amino acids in 107 samples representing 22 food ingredients were determined using 6-week-old broiler chickens. The ingredients assayed included five cereals (barley, maize, sorghum, triticale and wheat), two cereal by-products (rice polishings and wheat middlings), four oilseed meals (canola, cottonseed, soya-bean and sunflower meals), full-fat canola, maize gluten meal, four grain legumes (chickpeas, faba beans, field peas and lupins) and five animal protein sources (blood, feather, fish, meat and meat and bone meals). The mean ileal digestibility coefficients of amino acids in wheat and maize were higher than those in sorghum, triticale and barley. However, variations observed in individual amino acid digestibilities among samples within cereal type were greater than those determined between cereals. Threonine and lysine were the least digestible indispensable amino acids in the five cereals evaluated. The most digestible indispensable amino acid was phenylalanine in wheat and, leucine in maize and sorghum. In the case of the wheat middlings and rice polishings, threonine was the least digestible indispensable amino acid and arginine was the best digested.In the oilseed meals assayed, amino acid digestibility was highest for soya-bean and sunflower meals, intermediate for canola meal and lowest for cottonseed meal. Ileal digestibility coefficients of amino acids in lupins were found to be slightly lower than those in soya-bean meal. The amino acid digestibilities of field peas, faba beans and chickpeas were considerably lower than those of lupins. Digestibility of arginine was the highest and that of threonine was the lowest of the indispensable amino acids in oilseed meals and grain legumes, except in cottonseed meal. Lysine was the least digestible amino acid in cottonseed meal.In the animal protein sources assayed, digestibility coefficients of amino acids in blood meal were high, intermediate in fish meal, and low in meat meal, meat and bone meal and feather meal. Variation in amino acid digestibility coefficients determined for blood meal samples was small. However, wide variations in amino acid digestibilities were observed for other animal protein sources, highlighting significant batch-to-batch differences. In particular, marked variations were determined for meat meal and meat and bone meal samples. Cystine was the least digested amino acid in animal protein meals, with the exception of blood meal in which isoleucine had the lowest digestibility. The limitations of using apparent digestibility values in diet formulations and the concept of the standardized digestibility system to overcome these limitations are discussed.

Nutritional value of white lupins (Lupinus albus) for broilers: apparent metabolisable energy, apparent ileal amino acid digestibility and production performance

“…The CP and crude fat contents determined for the three cultivars were within the range of 300 to 410 and 59 to 146 g/kg, respectively, reported in the literature (Gatel, 1994;Petterson et al, 1997). The amino acid profiles of the lupin cultivars are in agreement with those reported by Green and Oram (1983) and Ravindran et al (2005). White lupins were moderately good sources of lysine, but were poor in sulphur-containing amino acids, which are characteristics of grain legumes in general (Gatel, 1994).…”

“…No cultivar effects were observed on the AIDC of amino acids. Only one previous study has reported the ileal amino acid digestibility of white lupins for broilers (Ravindran et al, 2005). On average, the apparent ileal digestibility values determined in this study were higher than those reported by Ravindran et al (2005), which may be explained by differences in the assay methodology.…”

“…On day 35, all birds were euthanised by an intracardial injection of sodium pentobarbitone solution and the contents of the lower half of the ileum were collected according to the procedures of Ravindran et al (2005). The ileum was defined as that portion of the small intestine extending from the Meckel's diverticulum to a point approximately 40 mm proximal to the ileo-caecal junction.…”

“…The ileum was divided into two halves and the digesta was collected from the lower half towards the ileo-caecal junction. Digesta from birds within a cage were pooled and processed as described by Ravindran et al (2005). The diet and digesta samples were then analysed for DM, titanium oxide and amino acids.…”

“…Published data on the apparent metabolisable energy (AME; Brenes et al, 1993;Hughes et al, 1998) and the ileal amino acid digestibility (Ravindran et al, 2005) of white lupins for broilers are scant. Moreover, data available on the energy value and amino acid digestibility of grain legumes have often been obtained in studies that have evaluated only one sample of the legume.…”