Eicher S D, Morrill J L, Velazco J
Kansas State University, Manhattan 66506-1600, USA.
J Dairy Sci. 1997 Feb;80(2):393-9. doi: 10.3168/jds.S0022-0302(97)75949-6.
Two experiments were conducted to examine the effects of the form of alpha-tocopherol or interactions of alpha-tocopherol with vitamin A on its bioavailability. In Experiment 1, Holstein steers were fed a diet that was low in vitamins A and E for 1 mo; then, steers were blocked by body weight (X = 97.5 kg) and assigned randomly to one of four oral treatments: 1) no added vitamins, 2) 442 mg of retinyl acetate, 3) 1342 mg of D-alpha-tocopherol, or 4) 442 mg of retinyl acetate and 1342 mg of D-alpha-tocopherol. Each treatment was given as a pulse dose. Blood was sampled over a 36-h period. Concentrations of plasma retinyl palmitate peaked at 2 to 6 h postsupplementation for all calves and then peaked again at 22 to 28 h for calves receiving vitamin supplements. Concentrations of plasma alpha-tocopherol peaked earliest with D-alpha-tocopherol supplementation alone at 12 to 20 h after supplementation, but simultaneous supplementation with retinyl acetate resulted in lower plasma alpha-tocopherol concentrations. Plasma retinyl palmitate decreased during peak alpha-tocopherol concentrations. In Experiment 2, blood and tissue were analyzed after a single gastric tube administration of a powder (DL-alpha-tocopheryl acetate) or a liquid (D-alpha-tocopherol) form of vitamin E to Holstein calves. Plasma and kidney concentrations of alpha-tocopherol were higher when calves were fed D-alpha-tocopherol than when calves were fed the DL-alpha-tocopherol acetate form. Concentrations in the liver, spleen, adipose tissue, heart, muscle, cellular blood fraction, and gut did not differ between the two forms.
进行了两项实验，以研究α-生育酚形式或α-生育酚与维生素A的相互作用对其生物利用度的影响。在实验1中，给荷斯坦公牛饲喂维生素A和E含量低的日粮1个月；然后，根据体重（X = 97.5千克）对公牛进行分组，并随机分配到四种口服处理之一：1）不添加维生素，2）442毫克醋酸视黄酯，3）1342毫克D-α-生育酚，或4）442毫克醋酸视黄酯和1342毫克D-α-生育酚。每种处理均以脉冲剂量给予。在36小时内采集血液样本。所有犊牛血浆视黄醇棕榈酸酯浓度在补充后2至6小时达到峰值，然后接受维生素补充剂的犊牛在22至28小时再次达到峰值。单独补充D-α-生育酚时，血浆α-生育酚浓度最早在补充后12至20小时达到峰值，但同时补充醋酸视黄酯会导致血浆α-生育酚浓度降低。在α-生育酚浓度峰值期间，血浆视黄醇棕榈酸酯浓度下降。在实验2中，对荷斯坦犊牛单次经胃管给予粉末状（DL-α-生育酚醋酸酯）或液体状（D-α-生育酚）维生素E后，对血液和组织进行分析。犊牛饲喂D-α-生育酚时，血浆和肾脏中的α-生育酚浓度高于饲喂DL-α-生育酚醋酸酯形式时。两种形式在肝脏、脾脏、脂肪组织、心脏、肌肉、细胞血液部分和肠道中的浓度没有差异。
