Tabiri H Y, Bertolo R F P, Ball R O, Korver D R
Department of Agricultural, Food and Nutritional Science, University of Alberta Edmonton, Canada.
Poult Sci. 2002 Oct;81(10):1516-21. doi: 10.1093/ps/81.10.1516.
Amino acid requirements of broiler breeder chickens are not well known. The indicator amino acid oxidation (IAAO) technique was adapted for use in broiler breeders as a rapid and sensitive method to determine amino acid requirements. During IAAO, phenylalanine oxidation decreases, inversely to the changes in protein synthesis, as the intake of the limiting test amino acid increases from deficient to adequate. Above the adequate level, phenylalanine oxidation remains constant. Before IAAO can be employed, the optimum priming and constant infusion doses of phenylalanine must be determined. Prelaying catheterized birds aged 20 to 24 wk were placed in closed oxidation chambers attached to a breath collection apparatus. A constant L-[1-(14)C]phenylalanine dose of 3.5 microCi/kg BW/h and priming doses of 4.5, 5.5, and 7.0 microCi/kg BW were used to determine optimal prime:constant dose ratios, minimum time taken for breath 14CO2 excretion to become constant (plateau), and adequate percentage of phenylalanine oxidized. At this constant infusion rate, the optimal priming dose of L-[1-(14)C]phenylalanine was 5.5 microCi/kg BW, resulting in a prime:constant dose ratio of 1.6:1. By using this ratio, the average time taken for breath 14CO2 to reach plateau was 60 min. Average phenylalanine oxidation at plateau, corrected for bicarbonate retention, was 5.5 +/- 1.4% (mean +/- SD), which is adequate for IAAO studies using deficient-to-excess levels of test amino acids. To the authors' knowledge, this study is the first in chickens to establish a primed, constant infusion technique using L-[1-(14)C]phenylalanine. The IAAO technique will be used in future studies to determine amino acid requirements in chickens.
肉种鸡的氨基酸需求尚不明确。指示剂氨基酸氧化（IAAO）技术被应用于肉种鸡，作为一种快速且灵敏的方法来测定氨基酸需求。在IAAO过程中，随着限制性试验氨基酸的摄入量从不足增加到充足，苯丙氨酸氧化减少，与蛋白质合成的变化呈反比。在充足水平以上，苯丙氨酸氧化保持恒定。在使用IAAO之前，必须确定苯丙氨酸的最佳预充量和持续输注剂量。将20至24周龄的产蛋前插管鸡置于连接有呼气收集装置的封闭氧化室中。使用3.5微居里/千克体重/小时的恒定L-[1-(14)C]苯丙氨酸剂量以及4.5、5.5和7.0微居里/千克体重的预充量，以确定最佳预充量与持续剂量的比例、呼出14CO2排泄达到恒定（平台期）所需的最短时间以及苯丙氨酸氧化的充足百分比。在这个恒定输注速率下，L-[1-(14)C]苯丙氨酸的最佳预充量为5.5微居里/千克体重，预充量与持续剂量的比例为1.6:1。使用这个比例，呼出14CO2达到平台期的平均时间为60分钟。平台期苯丙氨酸平均氧化率，经碳酸氢盐潴留校正后为5.5±1.4%（平均值±标准差），这对于使用从不足到过量水平的试验氨基酸进行IAAO研究来说是足够的。据作者所知，本研究是首次在鸡中建立使用L-[1-(14)C]苯丙氨酸的预充、持续输注技术。IAAO技术将在未来的研究中用于确定鸡的氨基酸需求。
