title: An assessment of the influence of macronutrients on growth performance and nutrient utilisation in broiler chickens by nutritional geometry.
abstract: The right-angled triangle mixture experiment was designed to include fourteen diets with different concentrations of starch, protein and lipid. Experimental diets were offered to male Ross 308 broiler chickens from 10 to 23 d after hatching, and response curves and surfaces were generated to illustrate the influence of macronutrients on growth performance and nutrient utilisations. Despite the primary function of macronutrients, especially protein, may not be providing energy, macronutrients were expressed as energy derived from starch, protein and fat for statistical purposes in the mixture design. Energy derived from lipid had a greater impact on feed intake than energy derived from starch and protein. When we compared the influence of starch and protein on feed intake, 'equal distance rule' was observed, which means the animal consumes feed to the point on its respective nutritional rails where the shortage of starch exactly equals the surplus of consumed protein. Increasing the protein-derived energy intake increased weight gain in broiler chickens, whereas energy intake derived from starch and lipid had little impact on weight gain. Feed conversion ratio (FCR) may be reduced by either increasing protein energy intake or decreasing starch energy intake. As the slope of the contours was less than 1, the influence of starch energy intakes on FCR exceeded that of protein energy intakes. In conclusion, energy derived from protein is more important than non-protein energy in terms of weight gain, and a balance between protein and energy supplies is required for efficient muscle protein deposition.
authors.affiliation: 1Poultry Research Foundation, Faculty of Veterinary Science,The University of Sydney,Camden,NSW 2570,Australia.
authors.forename: Sonia Y
authors.initials: SY
authors.lastname: Liu
authors.affiliation: 1Poultry Research Foundation, Faculty of Veterinary Science,The University of Sydney,Camden,NSW 2570,Australia.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Selle
authors.affiliation: 2School of Life and Environmental Sciences,The University of Sydney,Sydney,NSW 2006,Australia.
authors.forename: David
authors.initials: D
authors.lastname: Raubenheimer
authors.affiliation: 4Feedworks,PO Box 369,Romsey,VIC 3434,Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Cadogan
authors.affiliation: 3Charles Perkins Centre,The University of Sydney,Sydney,NSW 2006,Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Simpson
authors.affiliation: 1Poultry Research Foundation, Faculty of Veterinary Science,The University of Sydney,Camden,NSW 2570,Australia.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Cowieson
mesh_terms: D000465:Algorithms; D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D017849:Animals, Inbred Strains; D002364:Caseins / Q000008:administration & dosage* / Q000378:metabolism; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004063:Digestion; D002149:Energy Intake; D007408:Intestinal Absorption; D008297:Male; D008954:Models, Biological; D009517:New South Wales; D009751:Nutritional Requirements; D010938:Plant Oils / Q000008:administration & dosage* / Q000378:metabolism; D015203:Reproducibility of Results; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000378:metabolism; D013213:Starch / Q000008:administration & dosage* / Q000378:metabolism; D000074242:Sunflower Oil; D015430:Weight Gain
chemical_list: D000596:Amino Acids; D002364:Caseins; D010938:Plant Oils; D030262:Soybean Proteins; D000074242:Sunflower Oil; D013213:Starch
keywords:  AME apparent metabolisable energy;  AMEn
                  N-corrected AME;  FCR feed conversion ratio; Broiler chickens; Geometric framework; Lipids; Macronutrients; Protein; Starch