Zarghi Heydar, Ghavi Saeed
Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Vet Med Sci. 2024 May;10(3):e1460. doi: 10.1002/vms3.1460.
In the broiler's diets based on corn-soya bean meal, methionine (Met) and cystine (Cys), known as sulphur amino acids (SAAs), are the first limiting indispensable amino acids because of their limited presence, which are supplemented with different synthetic sources. Evaluation of the biological effectiveness of these sources can be important in their correct replacement, especially in the starter and growth diets.
The current study was done to assess the relative biological efficacy (RBE) of liquid Met hydroxy analogue-free acid (MHA-FA) in comparison with dl-Met (dl-Met) based on broiler performance traits at different levels of digestible SAA in the 1-11 (starter) and 11-25 (grower) days of age periods.
Two experiments were developed with treatments consisting of a basal diet without Met addition that met the nutrient and energy requirements of broilers with the exception of SAAs (Met + Cys) and five increasing Met doses for both sources (dl-Met and/or MHA-FA), resulting in digestible SAA concentrations from 0.62% to 1.02% of diet in the starter period (Trial 1) and 0.59% to 0.94% of diet in the grower period (Trial 2). The multi-linear regression model and slope ratio method were employed to calculate the RBE of MHA-FA compared with dl-Met for measured variables.
In both experiments, the results obtained during the starter and grower periods with the different Met supplementations show significant growth responses to digestible SAAs levels. By increasing dietary dl-Met and/or MHA-FA levels, the growth performance traits and immune responses were improved (quadratic; p < 0.05). The RBE of MHA-FA compared to dl-Met on an equimolar basis was estimated 66%-89% (59%-79% on a weight-to-weight basis).
It is concluded that the RBE of MHA-FA in comparison with dl-Met depends on broiler chicken age and what attribute is being evaluated.
在以玉米 - 豆粕为基础的肉鸡日粮中，蛋氨酸（Met）和胱氨酸（Cys），即硫氨基酸（SAAs），因其含量有限而成为首要限制的必需氨基酸，通常会添加不同的合成来源。评估这些来源的生物学有效性对于正确替代它们很重要，尤其是在雏鸡和生长鸡日粮中。
本研究旨在根据1至11日龄（雏鸡期）和11至25日龄（生长期）不同可消化SAA水平下的肉鸡生产性能指标，评估液体蛋氨酸羟基类似物游离酸（MHA - FA）与dl - 蛋氨酸（dl - Met）相比的相对生物学效价（RBE）。
开展了两项试验，处理包括不添加蛋氨酸的基础日粮，该日粮满足肉鸡除SAAs（蛋氨酸 + 胱氨酸）外的营养和能量需求，以及两种来源（dl - 蛋氨酸和/或MHA - FA）的五个递增蛋氨酸剂量，使得雏鸡期日粮中可消化SAA浓度从0.62%至1.02%（试验1），生长期日粮中从0.59%至0.94%（试验2）。采用多线性回归模型和斜率比法计算MHA - FA与dl - 蛋氨酸相比的RBE用于测量变量。
在两项试验中，雏鸡期和生长期不同蛋氨酸添加量下获得的结果表明，生长性能对可消化SAA水平有显著反应。通过提高日粮中dl - 蛋氨酸和/或MHA - FA水平，生长性能指标和免疫反应得到改善（呈二次曲线；p < 0.05）。基于等摩尔基础，MHA - FA与dl - 蛋氨酸相比的RBE估计为66% - 89%（基于重量对重量基础为59% - 79%）。
得出结论，MHA - FA与dl - 蛋氨酸相比的RBE取决于肉鸡年龄以及所评估的属性。
