Development of a precision-fed ileal amino acid digestibility assay using 3-week-old broiler chicks

• Published in: Poultry science Vol. 90; no. 2; pp. 396 - 401
• Main Authors: Kim, E.J, Utterback, P.L, Parsons, C.M
• Format: Journal Article
• Language: English
• Published: England Poultry Science Association 01.02.2011
• Subjects: accuracy; amino acids; Amino Acids - metabolism; Animal Feed - analysis; Animal Nutritional Physiological Phenomena; Animals; Biological Assay; broiler chickens; broiler feeding; Chickens - physiology; chicks; Diet - veterinary; digestibility; Digestion - physiology; fasting; feed deprivation; feeding level; feeds; Food Deprivation; ileum; Ileum - physiology; Male; methodology; precision; restricted feeding; starter diets; validity
• ISSN: 0032-5791; 1525-3171
• DOI: 10.3382/ps.2010-01088

The objective of these studies was to develop a precision-fed ileal digestibility assay, primarily for amino acids (AA), using 3-wk-old broiler chicks. For all experiments, day-old Ross x Ross 708 broiler chicks were fed a standard corn-soybean meal starter diet until 21 d of age. In experiment 1, feed was removed and excreta were collected at 2, 4, 6, 8, 10, 12, and 14 h after feed withdrawal. Results indicated that 8 h of feed withdrawal was sufficient to empty the ileum of feed residues. In a subsequent experiment, chicks were fasted overnight for 10 h and then tube-fed various amounts (from 6 to 15 g) of a corn-soybean meal mixture (60:40). Ileal digesta from Meckel's diverticulum to the ileo-cecal junction were then collected at various collection times between 3 and 7 h postfeeding. Results indicated that the amount of digesta in the distal ileum was generally maximized by 4 h postfeeding and by feed intakes of 9 g or greater. Based on the results of the previous study, apparent and standardized ileal digestibility values of AA in a corn-soybean meal chick starter diet were then determined at 2, 3, and 4 h postfeeding. Digestibility values were similar for the 3- and 4-h collection times, but were numerically or significantly (P [less-than or equal to] 0.05) lower at the 2-h collection time. The results of this study indicate that ileal AA digestibility can easily be determined in 3-wk-old broiler chicks when using a precision-fed assay. For such an assay, it is recommended that the chicks be fasted for at least 8 h before tube-feeding, that they be precision-fed approximately 10 g of feed, and that the ileal contents be collected at approximately 4 h postfeeding.