Abstract

1. Two experiments were conducted to determine the effects of different methionine (Met) sources regarding their absorption kinetics and utilisation in female single-meal-fed broiler chickens.

2. A total of 340, one day old female Ross 308 broiler chickens were fed commercial starter and grower diets for 38 d. Birds were then allocated to treatment diets in two experiments as a completely randomised design with four replicates of five chicks per each until 60 d of age. In experiment 1, a 2×5 factorial design was used to investigate the effect of two sources (DL-Met and AQUAVI®Met-Met) and five equimolar levels (0.4, 0.8, 1.2, 1.6, and 2 g/kg) in the diet. In experiment 2, different proportions of protein-bound methionine (PB-Met) to DL-Met (0.4:1.6, 0.8:1.2, 1.2:0.8: 1.6:0.4, and 2:0 g/kg) were incorporated into a basal diet deficient in Met. During the experiment, chickens received 90 g of pelleted feed for a time period of 17±2.5 min, once daily.

3. The results indicated that chickens fed diets supplemented with DL-Met and Met-Met showed a rapid rise in plasma Met 1 h after feeding, with a sudden drop at 2 h after feeding. In contrast, chickens fed PB-Met substituted diets showed a gradual plasma peak at 1 and 2 h postprandial (P<0.01). Plasma homocysteine (HCY) content increased to 34.38 and 40.43 μmol/l with DL-Met_2.0 and Met-Met_2.0 diets, while it decreased to 25.68 μmol/l with PB-Met_2.0(P≤0.01). Chickens that received the PB-Met_2.0 diet had higher (P≤0.01) protein utilisation (0.54 g/g) and lower excreta nitrogen content (4.04 g/100 g excreta), which demonstrated the benefits of feeding a protein-bound Met source. The efficiency of Met utilisation was 0.69 g/g in chickens fed PB-Met_2.0 diet, but only 0.36 and 0.41 g/g in those fed DL-Met_2.0 and Met-Met_2.0 (P≤0.01).

4. The observed utilisation coefficient of DL-Met and Met-Met for single-meal meat-type chickens was lower than expected. The synchronisation of intestinal Met absorption maintained the efficiency of utilisation, which was related to the sources of added Met, with protein-bound Met showing the best utilisation and least excretion.

摘要

1. 进行了两个实验，以确定不同蛋氨酸（Met）来源对雌性单餐饲喂肉鸡的吸收动力学和利用率的影响。

2. 共有340只1日龄的雌性Ross 308肉鸡饲养了38天的商业初学者和生长鸡日粮。然后在两个实验中将鸟类作为完全随机设计分配给治疗饮食，每个实验有四次重复，每只小鸡五只，直到60 d龄。在实验1中，采用2×5析因设计研究了两种来源（DL-Met和AQUAVI®Met-Met）和五个等摩尔水平（0.4、0.8、1.2、1.6和2 g / kg）的影响。饮食。在实验2中，将不同比例的蛋白质结合蛋氨酸（PB-Met）与DL-Met的比例（0.4：1.6、0.8：1.2、1.2：0.8：1.6：0.4和2：0 g / kg）掺入基础饮食缺乏蛋氨酸。在实验过程中，鸡每天一次接受90克颗粒饲料，时间为17±2.5分钟。

3. 结果表明，饲喂添加了DL-Met和Met-Met的日粮的鸡在饲喂1 h后血浆Met迅速升高，在饲喂2 h后突然下降。相反，饲喂PB-Met替代饮食的鸡在餐后1和2 h逐渐出现血浆峰值（P <0.01）。DL-Met _2.0和Met-Met _2. 0日粮的血浆同型半胱氨酸（HCY）含量分别增至34.38和40.43μmol/ l ，而PB-Met ₂ . 0日均降低至25.68μmol/ l （P≤0.01）。收到PB-Met _2.0的鸡日粮的蛋白质利用率较高（P≤0.01）（0.54 g / g），而排泄物中的氮含量较低（4.04 g / 100 g排泄物），这证明了饲喂蛋白质结合的Met源的好处。饲喂PB-Met ₂ .0日粮的鸡的Met利用效率为0.69 g / g，饲喂DL-Met _2.0和Met-Met _2.0的鸡分别为0.36和0.41 g / g （P≤0.01）。

4. DL-Met和Met-Met对单餐肉类鸡的观察利用率低于预期。肠道Met吸收的同步保持了利用效率，这与添加的Met的来源有关，与蛋白质结合的Met显示出最佳的利用和最少的排泄。