Estimation of nitrogen maintenance requirements and potential for nitrogen deposition in fast-growing chickens depending on age and sex

• Published in: Poultry science Vol. 85; no. 8; pp. 1421 - 1429
• Main Authors: Samadi, F, Liebert, F
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford University Press 01.08.2006
• Subjects: Age Factors; Amino Acids - metabolism; animal age; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; broiler chickens; Chickens - genetics; Chickens - growth & development; Chickens - metabolism; dietary protein; Dietary Proteins - administration & dosage; Dietary Proteins - metabolism; Energy Intake; Female; gender differences; Male; mathematical models; Models, Biological; Nitrogen - administration & dosage; Nitrogen - metabolism; nitrogen balance; nutrient requirements; Nutritional Requirements; Nutritional Status; Predictive Value of Tests; protein deposition; Random Allocation; Sex Factors; Weight Gain - drug effects; protein deposition; nitrogen maintenance requirement; modeling protein metabolism; growth potential; growing chicken
• ISSN: 0032-5791; 1525-3171
• DOI: 10.1093/ps/85.8.1421

Experiments were conducted to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N deposition (ND(max)T) in fast-growing chickens depending on age and sex. In N-balance studies, 144 male and 144 female chickens (Cobb 500) were utilized in 4 consecutive age periods (I: 10 to 25 d; II: 30 to 45 d; III: 50 to 65 d; and IV: 70 to 85 d). The experimental diets contained high-protein soybean meal and crystalline amino acids as protein sources and 6 graded levels of protein supply (N1 = 6.6%; N2 = 13.0%; N3 = 19.6%; N4 = 25.1%; N5 = 31.8%; and N6 = 37.6% CP in DM). The connection between N intake and total N excretion was fitted for NMR determination by an exponential function. The average NMR value (252 mg of N/BW(kg)0.67 per d) was applied for further calculation of ND(max)T as the threshold value of the function between N intake and daily N balance. For estimating the threshold value, the principle of the Levenberg-Marquardt algorithm within the SPSS program (Version 11.5) was applied. As a theoretical maximum for ND(max)T, 3,592, 2,723, 1,702, and 1,386 mg of N/BW(kg)0.67 per d for male and 3,452, 2,604, 1,501, and 1,286 mg of N/BW(kg)0.67 per d for female fast-growing chickens (corresponding to age periods I to IV) were obtained. The determined model parameters were the precondition for modeling of the amino acid requirement based on an exponential N-utilization model and depended on performance and dietary amino acid efficiency. This procedure will be further developed and applied in the subsequent paper.