title: Effects of age on nutrient digestibility in chicks fed different diets.
abstract: Three experiments were conducted to determine the effects of age on apparent MEn and apparent amino acid (AA) digestibility of various diets for New Hampshire x Columbian (Experiments 1 and 2) and commercial broiler (Experiment 3) male chicks. Excreta were collected at 0 to 2, 3 to 4, 7, 14, and 21 d of age in all experiments, and nutrient digestibility was determined using acid-insoluble ash as a marker. The first experiment evaluated a corn-soybean meal (SBM) diet. Both MEn and digestibility of AA increased with age, and broken-line regression analysis predicted a plateau at 14 d for MEn and 10 d of age for AA digestibility. For example, MEn increased from 2,970 to 3,430 kcal/kg DM, and lysine digestibility increased from 78 to 89% between 0 and 14 d of age. The second experiment evaluated cornstarch-crystalline AA, dextrose-casein, corn-SBM, and corn-canola meal diets. The MEn of the corn-SBM, corn-canola meal, and cornstarch-crystalline AA diets increased from 0 to 14 d of age. In contrast, the MEn of the dextrose-casein diet was high (3,800 kcal/kg DM) immediately after hatching and did not increase substantially with increasing age. Digestibility of AA increased with age for the corn-SBM and corn-canola meal diets, and broken-line regression analysis again predicted a plateau at approximately 10 d of age. Conversely, AA digestibility of the dextrose-casein and cornstarch-crystalline AA diets was high immediately after hatching (93 to 96%) and increased only slightly with age. The results of Experiment 3 with commercial broiler chicks also showed significant (P < 0.05) increases in MEn and AA digestibility with increasing age. The results of this study indicated that the MEn and AA digestibility of corn-SBM and corn-canola meal diets increase with age for young chicks. The results also showed that MEn and AA digestibility were very high for a dextrose-casein diet immediately after hatching. Thus, the latter ingredients may have beneficial effects for very young chicks.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Batal
authors.forename: C M
authors.initials: CM
authors.lastname: Parsons
mesh_terms: D000375:Aging; D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002364:Caseins / Q000008:administration & dosage; D002645:Chickens / Q000502:physiology*; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism; D004063:Digestion; D002149:Energy Intake; D004734:Energy Metabolism; D005947:Glucose / Q000008:administration & dosage; D012044:Regression Analysis; D013025:Glycine max; D013213:Starch / Q000008:administration & dosage / Q000378:metabolism; D015430:Weight Gain; D003313:Zea mays
chemical_list: D000596:Amino Acids; D002364:Caseins; D004041:Dietary Fats; D004044:Dietary Proteins; D013213:Starch; D005947:Glucose