Pantoja J, Firkins J L, Eastridge M L, Hull B L
Department of Animal Sciences, Ohio State University, Columbus 43210, USA.
J Dairy Sci. 1996 Apr;79(4):575-84. doi: 10.3168/jds.S0022-0302(96)76402-0.
Six cannulated cows were assigned to six treatments in a 6 x 6 Latin square design to evaluate the effects of fat saturation and amount and source of effective fiber on fatty acid metabolism. Cows were fed a control diet with no added fat or diets with 5% added fat from saturated tallow, tallow, or animal-vegetable fat; the diets with animal-vegetable fat had three percentages of effective fiber: 40% forage, 40% forage plus 20% soyhulls, or 60% forage. Cows fed diets supplemented with fat tended to have more disappearance of total fatty acids in the rumen than did those fed the control diet. Disappearance of fatty acids from the rumen, especially C16 and C18, was higher for cows fed the low fiber diet. The apparent digestibility of fatty acids in the small intestine was higher for cows fed the control diet than for those fed supplemental fat. Apparent digestibility also was reduced as fat saturation increased, primarily because of saturated tallow. Digestibility of C18:1 in saturated tallow was reduced, apparently in association with other saturated fatty acids. Fiber source had no effects on apparent intestinal digestibility of fatty acids. Concentrations of C18:0 and C18:1 in milk fat increased as the degree of fat saturation decreased, reflecting higher unsaturated C18 intake and ruminal biohydrogenation of polyunsaturated C18 fatty acids.
六头装有瘘管的奶牛被按照6×6拉丁方设计分配到六种处理组中，以评估脂肪饱和度、有效纤维的量和来源对脂肪酸代谢的影响。给奶牛饲喂不添加脂肪的对照日粮，或添加5%饱和牛脂、牛脂或动植物脂肪的日粮；添加动植物脂肪的日粮有三种有效纤维比例：40%粗饲料、40%粗饲料加20%大豆皮或60%粗饲料。与饲喂对照日粮的奶牛相比，饲喂添加脂肪日粮的奶牛瘤胃中总脂肪酸的消失量往往更多。低纤维日粮组奶牛瘤胃中脂肪酸的消失量更高，尤其是C16和C18脂肪酸。与饲喂添加脂肪日粮的奶牛相比，饲喂对照日粮的奶牛小肠中脂肪酸的表观消化率更高。随着脂肪饱和度增加，表观消化率也降低，主要是由于饱和牛脂。饱和牛脂中C18:1的消化率降低，显然与其他饱和脂肪酸有关。纤维来源对脂肪酸的小肠表观消化率没有影响。乳脂中C18:0和C18:1的浓度随着脂肪饱和度的降低而增加，这反映了不饱和C18摄入量的增加以及多不饱和C18脂肪酸的瘤胃生物氢化作用。
