Rukkwamsuk T, Geelen M J, Kruip T A, Wensing T
Department of Large Animal Medicine and Nutrition, Graduate School of Animal Health, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
J Dairy Sci. 2000 Jan;83(1):52-9. doi: 10.3168/jds.S0022-0302(00)74854-5.
We investigated the composition of fatty acids in adipose tissue, serum, and liver of cows that were fed at restricted energy intake or were overfed during the dry period. Overfed cows had higher concentrations of serum nonesterified fatty acids and consequently accumulated greater amounts of triacylglycerols in the liver than did cows that were fed at restricted energy intake. The percentages of the different fatty acids present in adipose tissue were similar for both groups and did not change during sampling intervals. Before parturition, concentrations of the individual fatty acids present in serum were similar between groups. After parturition, concentrations of major fatty acids in serum, including palmitic, stearic, oleic, and linoleic acids significantly increased in both groups and were higher in overfed cows than in cows that were fed at restricted energy intake. The shift of concentrations of the different fatty acids present in the liver--as a result of increased lipolysis-was observed in palmitic, oleic, and linoleic acids but not stearic acid, suggesting that stearic acid is used by the liver (i.e., oxidation) or is considerably secreted through the milk, thereby not increasing in accumulation in the liver. In conclusion, different feeding regimens during the dry period do not influence the composition of fatty acids in adipose tissue. More intensive lipolysis results in increased concentrations of palmitic, stearic, oleic, and linoleic acids in the blood; subsequently, these fatty acids, excluding stearic acid, greatly accumulated in the liver.
我们研究了在干奶期能量摄入受限或过量饲喂的奶牛的脂肪组织、血清和肝脏中的脂肪酸组成。与能量摄入受限的奶牛相比，过量饲喂的奶牛血清中非酯化脂肪酸浓度更高，因此肝脏中积累的三酰甘油量更多。两组奶牛脂肪组织中不同脂肪酸的百分比相似，且在采样间隔期间没有变化。分娩前，两组奶牛血清中各脂肪酸的浓度相似。分娩后，两组奶牛血清中主要脂肪酸（包括棕榈酸、硬脂酸、油酸和亚油酸）的浓度均显著增加，且过量饲喂的奶牛高于能量摄入受限的奶牛。由于脂肪分解增加，肝脏中不同脂肪酸浓度的变化在棕榈酸、油酸和亚油酸中观察到，但硬脂酸未观察到，这表明硬脂酸被肝脏利用（即氧化）或通过乳汁大量分泌，因此在肝脏中的积累没有增加。总之，干奶期不同的饲养方案不会影响脂肪组织中脂肪酸的组成。更强的脂肪分解导致血液中棕榈酸、硬脂酸、油酸和亚油酸浓度增加；随后，除硬脂酸外，这些脂肪酸在肝脏中大量积累。
