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Title:Evaluation of several methods for detecting differences in amino acid digestibility among meat and bone meals
Author(s):Davis, Tara
Advisor(s):Parsons, Carl M.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Meat and Bone Meal
Pepsin Digestibility
Amino Acid Digestibility
Abstract:Digestibility or bioavailability of amino acids (AA) can vary greatly among meat and bone meals (MBM). Five methods were evaluated to determine AA digestibility or bioavailability among MBM samples; these were the pepsin nitrogen digestibility, the precision-fed cecectomized rooster AA digestibility, the precision-fed chick ileal AA digestibility, the standardized ileal amino acid chick digestibility, and the slope-ratio chick growth lysine bioavailability assays. Pepsin nitrogen digestibility was determined using two different pepsin concentrations, 0.02 and 0.002%. The precision-fed cecectomized rooster assay consisted of tube-feeding the test feed ingredient followed by quantitatively collecting excreta for 48 hours. When 16 different MBM samples were evaluated using this assay, AA digestibility values varied among samples and rooster AA digestibility values were significantly correlated with pepsin values; however, most of the variation was due to the two highest and two lowest digestibility samples. The latter indicated that the pepsin assay was sensitive only for detecting large differences among MBM samples. The precision-fed chick ileal AA assay was similar to the rooster assay except that at four hours post-feeding, chicks were humanely euthanized and digesta from the ileum were collected and analyzed for AA. When comparing the precision-fed rooster and chick assays for the two MBM with the highest and two lowest rooster digestibility values, the results confirmed a large difference in AA digestibility among the samples and the two assays were in general agreement. Four additional MBM varying in pepsin digestibility were then obtained and evaluated using the rooster assay and the standardized ileal AA chick assay wherein 16-day-old broiler chicks were ad libitum fed a test diet containing a MBM as the only source of dietary protein for a period of five days. The chicks were then humanely euthanized and digesta from the ileum were collected and analyzed for AA. A slope-ratio chick growth assay was also conducted wherein week-old chicks were fed a Lys deficient basal diet supplemented with two levels of crystalline test Lys or two levels of the four MBM. Results were in general agreement when comparing the pepsin nitrogen digestibility, the precision-fed cecectomized rooster, the standardized ileal AA digestibility chick, and the slope-ratio chick growth assay. However, results for the chick growth assay were less consistent than the results for the other three assays.
Issue Date:2013-02-03
Rights Information:Copyright 2012 Tara Davis
Date Available in IDEALS:2013-02-03
Date Deposited:2012-12

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