Ileal amino acid digestibility assay for the growing meat chicken--effect of the imposition of a fasting period and the nature of the test diet.
ABSTRACT 1. The objective of this study was to investigate the effects of cold-pelleting, the length of the fasting period before feeding of the test diet and the nature of the test diet on apparent ileal nitrogen (N) digestibility in the broiler chicken. 2. Four-week-old broiler chickens were given a pelleted or non-pelleted maize/soyabean meal (basal) diet. The birds were starved for 24 h, given a single test meal (25 g) by intubation and killed 4 h after the start of feeding by administration of a barbiturate, to allow sampling of ileal digesta (terminal 15 cm). Cold-pelleting did not affect apparent ileal N digestibility. 3. Four-week-old broiler chickens were fasted for 12 or 24 h and then received a test meal (1 h free access) of either a pelleted soyabean meal or a pelleted meat-and-bone meal diet or were continuously fed on one of the two diets. The imposition of a fast did not affect apparent ileal N digestibility. However, a 24 h fasting procedure was preferred, as the between animal variation for apparent ileal N digestibility was lower than for the 12 h fast or for continuous feeding. 4. Four-week-old broiler chickens were given either semi-synthetic starch-based diets containing maize, wheat bran, meat-and-bone meal or fish meal as the sole sources of protein or each of these diets in combination with the basal diet (50:50 on a dry matter basis). With the exception of the maize diet, the apparent ileal N digestibility values calculated by correcting for the digestibility of the basal dietary component were significantly lower than when digestibility was determined directly using a diet in which the respective proteins were the sole protein source. This implies that interactions between the dietary ingredients influence estimates of apparent ileal N digestibility.
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ABSTRACT: Three experiments were conducted with turkey poults to characterize the protein quality of a novel poultry by-product meal composed of aged fowl extruded with either corn (CHM) or wheat (WHM). In Experiment 1, a growth assay was conducted to determine a dietary protein response range for semipurified diets containing CHM or WHM as the sole sources of dietary protein. Diets contained 12, 15, and 18% CP, and there was a linear increase in BW with no significant differences between the 2 sources. The same dietary protein levels were used to determine the protein efficiency ratio (PER), net protein ratio (NPR), and apparent amino acid digestibility of CHM and WHM in Experiments 2 and 3. In Experiment 3, WHM and CHM were also compared with soybean meal (SBM) and meat and bone meal (MBM). In Experiment 2, there were no significant differences between CHM and WHM in PER or NPR, but the variability between levels of CP did account for a significant level of CP x source interaction (P < 0.05). In Experiment 3, there were no significant protein level effects on PER or NPR, but the values for MBM were consistently lower than those for CHM, WHM, and SBM. The apparent amino acid digestibility coefficients for MBM were also consistently lower than those for CHM and WHM. In conclusion, the extruded WHM and CHM products have acceptable protein quality and were better than MBM as single sources of dietary protein.Poultry Science 07/2006; 85(7):1193-9. · 1.52 Impact Factor
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ABSTRACT: 1. Two experiments were conducted to evaluate the use of date fibre as a partial replacement of maize as a source of energy for growing broiler chicken. In experiment 1, date fibre was given alone to determine apparent metabolisable energy (AME) and apparent ileal digestibility of amino acids and crude fibre. 2. Date fibre had lower AME content (8.7 vs 13.6 MJ/kg) and apparent ileal digestibility coefficients for dry matter (0.35 vs 0.83), crude fibre (0.20 vs 0.54) and amino acids. 3. Based on the results of experiment 1, a growth study was conducted to test the effect of exogenous enzymes on the nutritive value of date fibre (experiment 2). 4. Three date fibre contents (5, 10 and 15%) with and without enzyme supplementation were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of experiment 2, 160 birds were randomly selected and slaughtered to evaluate carcase and meat quality traits as well as measuring ileal viscosity. 5. Substitution of maize by 10 and 15% date fibre significantly depressed AME. Enzyme supplementation did not improve crude fibre digestibility. The inclusion of date fibre in the diets except at 5% decreased average daily gains, feed intake and feed conversion ratio. 6. Addition of date fibre caused a significant increase in the weights of total digestive tract, pancreas and caecum. Addition of date fibre or the exogenous enzyme had no significant effect on carcase or meat quality characteristics. 7. Date fibre increased ileal digesta viscosity compared to the control. Addition of the exogenous enzyme decreased the viscosity of the basal diets but had no effect on the date fibre diets.8. This study indicated that date fibre can be included at levels of 5% in broiler diets without affecting performance.British Poultry Science 03/2006; 47(1):73-82. · 1.15 Impact Factor
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ABSTRACT: Poultry diets are typically supplemented with DL-2-hydroxy-4(methylthio) butanoic acid (HMTBA, or the hydroxy analog of methionine) or DL-methionine (DLM). Although HMTBA and DLM provide methionine activity, they are structurally distinct molecules with different physiological characteristics until they are converted to L-methionine. The relative rates of intestinal HMTBA vs. DLM absorption have been controversial, and it has been claimed that HMTBA is not fully absorbed. We measured the uptake of HMTBA and DLM in an in vitro everted intestinal slice model. Sections of intestinal slices (jejunum and ileum) were incubated with 0.1 to 50 mM HMTBA that was radiolabeled or DLM that was radiolabeled, and absorption was measured by scintillation counting. The HMTBA uptake was equal to or greater than DLM absorption in each tissue and at every time point with one exception. Furthermore, the rates of HMTBA absorption were always equal to or significantly greater than DLM uptake. In a separate in vivo experiment, absorption of HMTBA and L-methionine was monitored along the entire gastrointestinal (GI) tract. Broilers were fed commercial-type corn-soy diets supplemented with 0.21% HMTBA. Digesta was collected from crop, proventriculus, gizzard, duodenum, jejunum, ileum, large intestine, and cloaca and analyzed for the concentration of free HMTBA and free methionine in each compartment. These studies demonstrated that HMTBA is absorbed completely and along the entire GI tract, especially the upper GI tract. Furthermore, there was a higher concentration of free L-methionine than HMTBA in the digesta from every segment distal to the gizzard.Poultry Science 10/2005; 84(9):1397-405. · 1.52 Impact Factor