1Department of Animal and Food Science,Animal Nutrition and Welfare Service (SNiBA),Facultat de Veterinària,Universitat Autònoma de Barcelona,08193 Bellaterra,Barcelona,Spain.
2Nutrition and Food Science Department - LiBiFOOD,Facultat de Farmàcia,Universitat de Barcelona,Joan XXIII s/n,08028 Barcelona,Spain.
Animal. 2018 Oct;12(10):2040-2048. doi: 10.1017/S1751731117003615. Epub 2018 Jan 8.
The aim of this study is to assess how the fat molecular structure and its glycerol-to-fatty acid ratio (G : FA) affect the fatty acid (FA) apparent absorption of palm oils in broiler chickens. The experimental diets were the result of a basal diet supplemented with 6% of different palm oils. Native palm oil (N), rich in triacylglycerols, was the positive control (T1), and acid palm oil (A), rich in free FA, was the negative control (T2). In order to improve the nutritive value of A, two different nutritional strategies were performed. The first strategy was achieved by adding increasing amounts of free glycerol (G) (4% (T3), 8% (T4) and 16% (T5)) to A, and the second one by adding increasing amounts of mono- (MAG) and diacylglycerols (DAG), coming from re-esterified palm oil (E) (40% (T6), 70% (T7), and 100% (T8)) to A. As a result, eight dietary treatments were formulated with a G : FA ratio ranging from 0.04 to 0.67. These treatments were randomly assigned to 192 one-day-old female broiler chickens (Ross 308), distributed in 48 cages. The results showed how, by keeping the G : FA ratio constant (0.33 mol/mol), the diet with a high MAG and DAG content (T7) achieved higher saturated FA apparent absorption values than did the diet with a high triacylglycerol content (T1) and this, in turn, more than did the diet with a high free FA content (T4). The behavior of oils with high or low G : FA ratio was dependent on whether G was in a free state or esterified as part of acylglycerol molecules. Thus, increasing amounts of G to A did not enhance the total FA apparent absorption, but rather quite the opposite, even impairing the absorption of mono- and polyunsaturated FA. However, increasing amounts of E (rich in MAG and DAG) to A (rich in FFA) did enhance total FA apparent absorption, primarily due to the increased absorption of saturated FA. In conclusion, the greater the G : FA ratio of a palm oil, the greater the absorption of total FA, as long as G is esterified as part of acylglycerol molecules. Thus, the re-esterification process for obtaining E makes sense in order to give added value to A, achieving even greater digestibility values than does its corresponding N.
本研究旨在评估脂肪分子结构及其甘油三酸酯与脂肪酸的比例（G:FA）如何影响肉鸡棕榈油中脂肪酸（FA）的表观吸收率。实验日粮是在基础日粮中添加 6%不同棕榈油的结果。天然棕榈油（N）富含三酰基甘油，是阳性对照（T1），富含游离脂肪酸的酸棕榈油（A）是阴性对照（T2）。为了提高 A 的营养价值，采用了两种不同的营养策略。第一种策略是向 A 中添加不同量的游离甘油（G）（4%（T3）、8%（T4）和 16%（T5）），第二种策略是向 A 中添加不同量的来自再酯化棕榈油（E）的单酰基甘油（MAG）和二酰基甘油（DAG）（40%（T6）、70%（T7）和 100%（T8））。结果，用 8 种不同的日粮处理方式，G:FA 比从 0.04 到 0.67 不等。这些处理方式被随机分配给 192 只 1 日龄雌性肉鸡（Ross 308），分布在 48 个笼子中。结果表明，通过保持 G:FA 比恒定（0.33mol/mol），高 MAG 和 DAG 含量的日粮（T7）比高三酰基甘油含量的日粮（T1）获得更高的饱和 FA 表观吸收率，而高游离 FA 含量的日粮（T4）的吸收率则低于前两者。高或低 G:FA 比油的行为取决于 G 是处于游离状态还是酯化在酰基甘油分子中。因此，向 A 中添加大量 G 并没有提高总 FA 的表观吸收率，反而适得其反，甚至会降低单不饱和和多不饱和 FA 的吸收率。然而，向富含游离脂肪酸的 A 中添加更多的 E（富含 MAG 和 DAG）确实提高了总 FA 的表观吸收率，这主要是由于饱和 FA 吸收的增加。总之，棕榈油的 G:FA 比越大，总 FA 的吸收率就越高，只要 G 酯化在酰基甘油分子中。因此，为了提高 A 的附加值，再酯化过程是有意义的，甚至可以获得比其相应的 N 更高的消化率值。
