Bregendahl K, Roberts S A, Kerr B, Hoehler D
Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
Poult Sci. 2008 Apr;87(4):744-58. doi: 10.3382/ps.2007-00412.
Seven separate experiments were conducted with Hy-Line W-36 hens to determine the ideal ratio of Arg, Ile, Met, Met+Cys, Thr, Trp, and Val relative to Lys for maximal egg mass. The experiments were conducted simultaneously and were each designed as a randomized complete block design with 60 experimental units (each consisting of 1 cage with 2 hens) and 5 dietary treatments. The 35 assay diets were made from a common basal diet (2,987 kcal/kg of ME; 12.3% CP; 4.06% Ca, 0.47% nonphytate P), formulated using corn, soybean meal, and meat and bone meal. The true digestible amino acid contents in the basal diet were determined using the precision-fed assay with adult cecectomized roosters. Crystalline L-Arg (free base), L-Ile, L-Lys.HCl, DL-Met, L-Thr, L-Trp, and L-Val (considered 100% true digestible) were added to the basal diet at the expense of cornstarch to make the respective assayed amino acid first limiting and to yield 5 graded inclusions of the assayed amino acid. Hens were fed the assay diets from 26 to 34 wk of age, with the first 2 wk considered a depletion period. Egg production was recorded daily and egg weight was determined weekly on eggs collected over 48 h; egg mass was calculated as egg production x egg weight. The requirement for each amino acid was determined using the broken-line regression method. Consumption of Arg did not affect egg mass, thus a requirement could not be determined. The true digestible amino acid requirements used to calculate the ideal amino acid ratio for maximum egg mass were 426 mg/d of Ile, 538 mg/d of Lys, 253 mg/d of Met, 506 mg/d of Met+Cys, 414 mg/d of Thr, 120 mg/d of Trp, and 501 mg/d of Val. The ideal amino acid ratio for maximum egg mass was Ile 79%, Met 47%, Met+Cys 94%, Thr 77%, Trp 22%, and Val 93% on a true digestible basis relative to Lys. The ideal Met and Met+Cys ratios were verified in an ensuing identical experiment with 52- to 58-wk-old hens.
用海兰W - 36母鸡进行了七项独立实验，以确定精氨酸（Arg）、异亮氨酸（Ile）、蛋氨酸（Met）、蛋氨酸+半胱氨酸（Met+Cys）、苏氨酸（Thr）、色氨酸（Trp）和缬氨酸（Val）相对于赖氨酸（Lys）的理想比例，以实现最大蛋重。实验同时进行，每项实验设计为随机完全区组设计，有60个实验单元（每个单元由1个笼子和2只母鸡组成）和5种日粮处理。35种测定日粮由一种通用基础日粮（代谢能2987千卡/千克；粗蛋白12.3%；钙4.06%，非植酸磷0.47%）制成，该基础日粮使用玉米、豆粕和肉骨粉配制。基础日粮中真可消化氨基酸含量采用成年去盲肠公鸡精确饲喂法测定。将结晶L-精氨酸（游离碱）、L-异亮氨酸、L-赖氨酸盐酸盐、DL-蛋氨酸、L-苏氨酸、L-色氨酸和L-缬氨酸（认为100%真可消化）添加到基础日粮中，以玉米淀粉为代价，使各自测定的氨基酸成为第一限制性氨基酸，并产生5个分级的测定氨基酸添加水平。母鸡在26至34周龄期间饲喂测定日粮，前2周视为耗尽期。每天记录产蛋量，每周测定收集48小时的鸡蛋的蛋重；蛋重以产蛋量×蛋重计算。使用折线回归法确定每种氨基酸的需求量。精氨酸的摄入量不影响蛋重，因此无法确定其需求量。用于计算最大蛋重的理想氨基酸比例的真可消化氨基酸需求量为：异亮氨酸426毫克/天、赖氨酸538毫克/天、蛋氨酸253毫克/天、蛋氨酸+半胱氨酸506毫克/天、苏氨酸414毫克/天、色氨酸120毫克/天、缬氨酸501毫克/天。基于真可消化的基础，相对于赖氨酸，最大蛋重的理想氨基酸比例为：异亮氨酸79%、蛋氨酸47%、蛋氨酸+半胱氨酸94%、苏氨酸77%、色氨酸22%、缬氨酸93%。在随后对52至58周龄母鸡进行的相同实验中验证了理想的蛋氨酸和蛋氨酸+半胱氨酸比例。
