Moter V, Stein H H
Department of Animal and Range Sciences, South Dakota State University, Brookings 57006, USA.
J Anim Sci. 2004 Dec;82(12):3518-25. doi: 10.2527/2004.82123518x.
An experiment was conducted to determine the effect of feed intake (FI) on endogenous losses and the digestibility of CP and AA by growing pigs. Six growing barrows (initial BW = 70.3 kg) had a T-cannula installed in the distal ileum and were used in a 6 x 6 Latin square design. A soybean meal cornstarch-based diet and a N-free diet were formulated. Chromic oxide (0.25%; as-fed basis) was included in both diets as an inert marker. Each diet was provided at three different levels of FI. Feed intake level 1 was equal to the estimated energy requirement for maintenance of the pigs, whereas levels 2 and 3 were two or three times this amount, respectively. Each experimental period lasted 7 d. The initial 4 d of each period comprised an adaptation period to the experimental diets. On d 5, fecal samples were collected, while ileal digesta were collected during two 10-h periods on d 6 and 7. Between each experimental period, a corn-soybean meal-based diet (16% CP) was fed to all pigs for 7 d. The basal ileal endogenous losses (IAA(end)) of CP and AA were measured for each level of FI from pigs fed the N-free diet. Likewise, the apparent (AID) and standardized (SID) ileal digestibility coefficients for CP and AA in soybean meal were calculated for each level of FI. The total-tract digestibility coefficient of energy in the soybean meal-based diet also was calculated. The AID for CP and all indispensable AA except Lys, Met, and Thr increased (P < or =0.055) as FI increased. The IAA(end) of CP and all AA except Pro decreased linearly (P < 0.05) as FI increased when expressed as g/kg of DMI; however, the total daily IAA(end) increased as FI increased (linear, P < or =0.056) for all AA, except for Phe, Thr, Trp, Val, Cys, Gly, and Ser. The AA composition (% of CP) of endogenous protein was not affected by the level of FI, except for Arg, Thr, Pro, and Ser. As FI increased, the SID decreased linearly (P < 0.04) for CP and all AA, except Arg, Trp, Asp, Pro, and Tyr. The total-tract digestibility of energy was not influenced by the FI level. These results demonstrate that the FI level significantly influenced AID, SID, and IAA(end) for CP and AA. Therefore, pigs used to measure AA digestibility coefficients and IAA(end) should be fed at a level that is close to what is used under commercial conditions.
进行了一项实验，以确定采食量（FI）对生长猪内源损失以及粗蛋白（CP）和氨基酸（AA）消化率的影响。六头生长公猪（初始体重=70.3千克）在回肠末端安装了T型套管，并采用6×6拉丁方设计。配制了一种以豆粕-玉米淀粉为基础的日粮和一种无氮日粮。两种日粮均添加了氧化铬（0.25%；以饲喂基础计）作为惰性标记物。每种日粮以三种不同的采食量水平提供。采食量水平1等于维持猪所需的估计能量，而水平2和3分别是该量的两倍或三倍。每个实验期持续7天。每个时期的前4天为适应实验日粮的阶段。在第5天收集粪便样本，在第6天和第7天的两个10小时时间段内收集回肠食糜。在每个实验期之间，给所有猪饲喂以玉米-豆粕为基础的日粮（粗蛋白含量16%）7天。测定了饲喂无氮日粮的猪在每个采食量水平下CP和AA的基础回肠内源损失（IAA(end)）。同样，计算了每个采食量水平下豆粕中CP和AA的表观（AID）和标准化（SID）回肠消化率系数。还计算了以豆粕为基础的日粮中能量的全肠道消化率系数。随着采食量增加，CP以及除赖氨酸、蛋氨酸和苏氨酸之外的所有必需氨基酸的AID增加（P≤0.055）。当以克/千克干物质采食量表示时，随着采食量增加，CP和除脯氨酸之外的所有氨基酸的IAA(end)呈线性下降（P<0.05）；然而，除苯丙氨酸、苏氨酸、色氨酸、缬氨酸、半胱氨酸、甘氨酸和丝氨酸之外，所有氨基酸的每日IAA(end)总量随着采食量增加而增加（线性，P≤0.056）。内源蛋白的氨基酸组成（占CP的百分比）不受采食量水平的影响，但精氨酸、苏氨酸、脯氨酸和丝氨酸除外。随着采食量增加，CP以及除精氨酸、色氨酸、天冬氨酸、脯氨酸和酪氨酸之外的所有氨基酸的SID呈线性下降（P<0.04）。能量的全肠道消化率不受采食量水平的影响。这些结果表明，采食量水平对CP和AA的AID、SID和IAA(end)有显著影响。因此，用于测定氨基酸消化率系数和IAA(end)的猪应以接近商业条件下的采食量水平进行饲喂。
