Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand.
Poult Sci. 2014 Feb;93(2):371-9. doi: 10.3382/ps.2013-03344.
Two experiments were conducted. The first experiment investigated the digestion of fat and fatty acids (FA) from soybean oil and tallow along the gastrointestinal tract of broiler chickens. The second experiment was conducted to determine endogenous fat and FA losses and the FA profile of chicken bile. In experiment 1, 2-wk-old broilers were fed corn-soy diets supplemented with 50 g/kg of soybean oil or tallow for 7 d and digesta were collected from the duodenum, upper jejunum, upper ileum, and lower ileum. Apparent digestibility coefficients were calculated using the titanium marker ratio in diets, and digesta. Digestibility of fat was determined to be negative in the duodenum, indicating marked net secretion of fat into this segment. Fat was rapidly digested in the jejunum, with digestibility coefficients of 0.60 to 0.64 being determined at the end of the jejunum. The digestion of fat continued in the upper ileum. The apparent digestibility coefficient of fat determined at lower ileum in soybean oil diets was higher (P < 0.05) than that in tallow diets (0.82 vs. 0.74). Linoleic acid was digested throughout the intestinal tract, whereas the digestion of palmitic, stearic, and oleic acids started only in the jejunum. Measurements at the lower ileal level showed that the unsaturated FA (linoleic and oleic acids) were well digested (0.90 to 0.94), irrespective of the source of fat. In contrast, the digestibility of saturated FA (palmitic and stearic acids) was influenced (P < 0.05) by the fat source. Digestibility coefficients of palmitic and stearic acids at lower ileum were markedly higher (P < 0.05) in the diet containing soybean oil (0.77 to 0.85) compared with that containing tallow (0.58 to 0.68). In experiment 2, ileal endogenous fat loss was determined to be 1,714 mg/kg of DM intake. Endogenous fat was composed mainly of palmitic (75 g/kg), stearic (131 g/kg), oleic (73 g/kg), linoleic (133 g/kg), and arachidonic (60 g/kg) acids. Fatty acid profile of endogenous fat was found to be remarkably similar to that of the bile, suggesting that the reabsorption of fat and FA from the bile was incomplete in growing broiler chickens.
进行了两项实验。第一项实验研究了肉鸡消化道中大豆油和牛脂中脂肪和脂肪酸（FA）的消化情况。第二项实验旨在确定内源性脂肪和 FA 损失以及鸡胆汁中的 FA 谱。在实验 1 中，2 周龄的肉鸡饲喂添加 50 g/kg 大豆油或牛脂的玉米-大豆日粮 7 d，并从十二指肠、空肠上段、空肠中段和回肠中收集食糜。利用日粮和食糜中的钛示踪剂比值计算表观消化率系数，脂肪在十二指肠中的消化率为负值，表明脂肪在此段有明显的净分泌。脂肪在空肠中迅速消化，空肠末端的消化率系数为 0.60 至 0.64。脂肪在回肠上段继续消化。在大豆油日粮中，回肠下段脂肪的表观消化率系数较高（P<0.05），高于牛脂日粮（0.82 对 0.74）。亚油酸在整个肠道中被消化，而棕榈酸、硬脂酸和油酸的消化仅在空肠中开始。在回肠下段的测量结果表明，不饱和 FA（亚油酸和油酸）消化良好（0.90 至 0.94），与脂肪来源无关。相比之下，饱和 FA（棕榈酸和硬脂酸）的消化受脂肪来源影响（P<0.05）。在含有大豆油的日粮中，回肠下段棕榈酸和硬脂酸的消化率系数明显较高（P<0.05）（0.77 至 0.85），而含有牛脂的日粮中（0.58 至 0.68）。在实验 2 中，确定回肠内源性脂肪损失为 1714 mg/kg 的 DM 摄入量。内源性脂肪主要由棕榈酸（75 g/kg）、硬脂酸（131 g/kg）、油酸（73 g/kg）、亚油酸（133 g/kg）和花生四烯酸（60 g/kg）组成。内源性脂肪的脂肪酸谱与胆汁非常相似，表明生长肉鸡对胆汁中的脂肪和 FA 的重吸收不完全。
