摘要
为寻求足以客观反应各种氨基酸生物学效价测值的最小样本含量,作者研究了喂饲蛋鸡日粮、肉鸡日粮、鱼粉日粮、菜籽饼日粮、豆粕日粮、玉米日粮和纯合无氮日粮等7组不同类型日粮时,试验鸡干物质排泄量、干物质表观代谢率和内源性氨基酸排泄量的个体测值变异规律,同时也研究了达到不同测试精度时,相应地所需要的试验鸡群数量。结果表明:(1)饲喂全价日粮和半纯合日粮时,试验鸡个体间干物质排泄量标准差为1.2～2.3g,变异系数为10.5％～17.4％;干物质表观代谢率标准差为2.8％～5.2％,变异系数为3.8％～12.6％。它表明饲喂不同日粮时,试验鸡个体间干物质排泄量和干物质表观代谢率测值差异程度不同。为了保证对各种日粮的干物质表观代谢率测值偏差小于3％和2％(置信度为95％)时,试验鸡数分别需要12只和27只。(2)饲喂纯合无氮日粮时,试验鸡个体间干物质排泄量及干物质表观谢率测值差异则更大。如从内源氨基酸排泄量测值分析,试验鸡个体间各种氨基酸排泄量变异系数都大于20％,因此,即使试验允许偏差值放宽到10％,仍需要40只左右的试验鸡群。
How to design suitable sample size of birds is one of the key problems in determing the availability of amino acid. The expense and labor for measuring amino acid content are the main difficulty for enlarging the sample size of test birds for eliminating the effect of higher variation of values of amino acid availability of eacb bird. This experiment studied the suitable sample size of test birds for meeting the need of different precision of the result in evaluating amino acid availability based on studying the variation of the data of dry matter of excreta, apparent metabolizability of dry matter and endogenous amino acids of 7 different type of test diets. Tbe results showed:(1)the proper group sizes of test birds varied with the properties of diets and feedstuffs for meeting the same precesion requirement. To assay a oiseed meal type diet needs relatively larger sample size, whereas to assay a higher energy feed needs relatively smaller sample size. If the test group contains 12 or 17 birds, the relative error of the assay can be less than 3％ or 2％ (P<0.05). (2)The sample size of the test birds for the evaluation of endogenous amino acid is relatively larger.
