1,721,131 research outputs found
Potential for protein deposition of growing chickens depending on genotype, age and sex and consequences for amino acid requirements
No full textPotential for protein deposition of growing chickens depending on genotype, age and sex and consequences for amino acid requirements
No full textThreonine Requirement of Slow-Growing Male Chickens Depends on Age and Dietary Efficiency of Threonine Utilization
No full textNitrogen-balance experiments were conducted with a total of 288 male chickens to assess Thr requirement data on 2 commercial slow-growing genotypes (I 657 and Red JA from Hubbard ISA) by use of a modeling procedure described previously. Six graded levels of dietary protein supply from high-protein soy-beanmeal were used within 4 age periods (period I: 10 to 25 d; period II: 30 to 45 d; period III: 5 to 65 d; and period IV: 70 to 85 d). The provided dietary amino acid ratio (Lys: Met + Cys: Thr = 1:0.85:0.54), with 3.87% Thr in the feed protein, identified Thr as the first limiting dietary amino acid. The nitrogen maintenance requirement (NMR) was established by exponential approximation of N excretion depending on N intake (on average, NMR = 173 mg of N/BWkg0.67 per d). The theoretical maximum for daily N deposition was estimated by the Levenberg-Marquardt algorithm (SPSS program, version 11.5) and by exponential fitting of N balance data depending on N intake. The observed dietary Thr efficiency was used to model Thr requirements for a given protein deposition depending on age. The optimal dietary Thr concentration (percentage of feed) was established by different predictions for daily feed intake. Daily CP deposition of approximately 60% of the potential required 0.83 and 0.87% (10 to 25 d), 0.73 and 0.75% (30 to 45 d), 0.66 and 0.69% (50 to 65 d), and 0.51 and 0.53% (70 to 85 d) of Thr in feed for genotype I 657 and genotype Red JA, respectively (average daily feed intakes of 30, 75, 100, and 100 g in age periods I to IV). Results of model calculations need verification in comparative growth studies with assessment of nutrient deposition and varying dietary Thr efficiencies
Lysine requirement of fast growing chickens –effects of age, sex, level of protein deposition and dietary lysine efficiency
No full textEstimation of Nitrogen Maintenance Requirements and Potential for Nitrogen Deposition in Fast-Growing Chickens Depending on Age and Sex
No full textExperiments were conducted to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N deposition (NDmaxT) 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 (1:10 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 (NI = 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/BWkg0.67 per d) was applied for further calculation of NDmaxT 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 NDmaxT 3,592, 2,723, 1,702, and 1,386 mg of N/BWkg0.67 per d for male and 3,452, 2,604, 1,501, and 1,286 mg of N/BWkg0.67 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
Lysine requirement of fast growing chickens –effects of age, sex, level of protein deposition and dietary lysine efficiency
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Nitrogen maintenance requirement and potential for nitrogen deposition of intensive growing chicken depending on age and sex
No full textZur Modellierung von Lysin- und Threoninbedarfswerten von Broilern unterschiedlicher genetischer Herkunft
No full textThreonine requirement of extensive broiler genotypes depending on performance and efficiency of threonine utilisation
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