Trouw Nutrition Research and Development, P.O. Box 299, Amersfoort3800-AG, The Netherlands.
Animal Nutrition Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen 6708 WD, The Netherlands.
Animal. 2019 Sep;13(9):1874-1882. doi: 10.1017/S1751731118003373. Epub 2018 Dec 27.
When supplementing lamb diets with vitamin E, an equivalence factor of 1.36 is used to discriminate between RRR-α-tocopheryl acetate and all-rac-α-tocopheryl acetate. However, more recent studies suggest a need for new equivalence factors for livestock animals. The current study aimed to determine the effect of RRR- and all-rac-α-tocopheryl acetate supplementation on α-tocopherol deposition in lamb tissues. A total of 108 Rasa Aragonesa breed lambs were fed increasing amounts of all-rac-α-tocopheryl acetate (0.25, 0.5, 1.0 and 2.0 g/kg compound feed) or RRR-α-tocopheryl acetate (0.125, 0.25, 0.5 and 1.0 g/kg compound feed) by adding them to a basal diet that contained 0.025 g/kg feed of all-rac-α-tocopheryl acetate as part of the standard vitamin and mineral mixture. The diets were fed for the last 14 days before slaughtering at 25.8±1.67 kg BW. Within 20 min after slaughter samples of muscle, heart, liver, brain and spleen were frozen at -20°C until α-tocopherol analysis. Increased supplementation of either vitamin E sources led to a significant increase (P < 0.001) in α-tocopherol concentration in all tissues studied. The tissue with the highest α-tocopherol concentration was the liver followed by spleen, heart and muscle. At similar supplementation levels (0.25, 0.50 and 1.0 g/kg compound feed), α-tocopherol content in the selected tissues was not affected by α-tocopherol source. However, the ratios between RRR- and all-rac-α-tocopheryl acetate increased with the increasing α-tocopherol supplementation (at 0.25 and 1.0 g/kg compound feed), from 1.06 to 1.16 in muscle, 1.07 to 1.15 in heart, 0.91 to 0.94 in liver and 0.98 to 1.10 in spleen. The highest relative proportion of Ʃ2S (sum of SSS-, SSR-, SRS- and SRR-α-tocopherol)-configured stereoisomers was found in the liver of lambs supplemented with all-rac-α-tocopheryl acetate accounting for up to 35 to 39% of the total α-tocopherol retained, whereas the proportion of Ʃ2S-configured stereoisomers in the other tissues accounted for <14%. Increasing all-rac-α-tocopheryl acetate supplementation was also found to affect the 2R-configured stereoisomer profile in muscle, heart and spleen with increasing proportions of RRS-, RSR- and RSS- at the cost of RRR-α-tocopherol. In all tissues, the relative proportion of all non-RRR-stereoisomers in lambs receiving RRR-α-tocopheryl acetate was lower than RRR-α-tocopherol. These results confirm that the relative bioavailability of RRR- and all-rac-α-tocopheryl acetate is dose- and tissue-dependent and that a single ratio to discriminate the two sources cannot be used.
当用维生素 E 补充羔羊的饮食时，使用等价因子 1.36 来区分 RRR-α-生育酚醋酸酯和全反式-α-生育酚醋酸酯。然而，最近的研究表明，家畜需要新的等价因子。本研究旨在确定 RRR-和全反式-α-生育酚醋酸酯补充对羔羊组织中 α-生育酚沉积的影响。总共 108 只 Rasa Aragonesa 品种羔羊被喂食不同量的全反式-α-生育酚醋酸酯（0.25、0.5、1.0 和 2.0 g/kg 复合饲料）或 RRR-α-生育酚醋酸酯（0.125、0.25、0.5 和 1.0 g/kg 复合饲料），通过向含有 0.025 g/kg 饲料的基础饮食中添加这些饲料来实现，该基础饮食作为标准维生素和矿物质混合物的一部分含有 0.025 g/kg 饲料的全反式-α-生育酚醋酸酯。在 25.8±1.67 kg BW 体重屠宰前的最后 14 天内喂食这些饲料。在屠宰后 20 分钟内，将肌肉、心脏、肝脏、大脑和脾脏的样本迅速冷冻在-20°C，直到进行 α-生育酚分析。两种维生素 E 来源的补充都显著增加（P<0.001）所有研究组织中的 α-生育酚浓度。α-生育酚浓度最高的组织是肝脏，其次是脾脏、心脏和肌肉。在类似的补充水平（0.25、0.50 和 1.0 g/kg 复合饲料）下，选定组织中的 α-生育酚含量不受 α-生育酚来源的影响。然而，随着 α-生育酚补充量的增加（在 0.25 和 1.0 g/kg 复合饲料），RRR-和全反式-α-生育酚醋酸酯之间的比例增加，肌肉中从 1.06 增加到 1.16，心脏中从 1.07 增加到 1.15，肝脏中从 0.91 增加到 0.94，脾脏中从 0.98 增加到 1.10。在补充全反式-α-生育酚醋酸酯的羔羊肝脏中发现最高的Σ2S（SSS-、SSR-、SRS-和 SRR-α-生育酚的总和）构型立体异构体的相对比例，占保留的总 α-生育酚的 35%至 39%，而其他组织中 Σ2S 构型立体异构体的比例<14%。还发现增加全反式-α-生育酚醋酸酯的补充也会影响肌肉、心脏和脾脏中 2R-构型立体异构体的分布，RRR-α-生育酚的比例增加，而 RRS-、RSR-和 RSS-的比例增加。在所有组织中，接受 RRR-α-生育酚醋酸酯的羔羊中所有非 RRR-立体异构体的相对比例均低于 RRR-α-生育酚。这些结果证实，RRR-和全反式-α-生育酚醋酸酯的相对生物利用度取决于剂量和组织，并且不能使用单一比值来区分这两种来源。
