Effects of fat-enriched diet and methionine on insulin sensitivity in lactating cows
Effects of fat-enriched diet and methionine on insulin sensitivity in lactating cows
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DOI：
10.2527/jas.2015-8868
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发表时间：
2015-06-01
影响因子：
3.3
通讯作者：
Kushibiki, S.
中科院分区：
文献类型：
--
作者：
Fukumori, R.;Sugino, T.;Kushibiki, S.
采用高胰岛素-正葡萄糖钳夹（EGC）技术研究了长链脂肪酸钙（LCFA-Ca）和过瘤胃蛋氨酸（RPM）对泌乳奶牛外周组织胰岛素敏感性的影响。6头经产荷斯坦奶牛被用于3 × 3拉丁方实验，在每个14天的时间。日粮处理为0（RPM 0）、20（RPM 20）和60（RPM 60）g/d RPM，并补充含有1.5% LCFA-Ca（等于奶牛ME需求量的110%）的日粮。作为3种含LCFA-Ca饮食的对照，还包括不含LCFA-Ca（Con）的饮食处理。经过10天的适应期后，收集4天的牛奶样品，并在每个处理期的第14天进行EGC实验。通过颈静脉导管以0.1、0.2、0.3和0.4 milliunits.kg BW-1.min（-1）的速率输注胰岛素溶液30 min，然后以0.5 milliunits.kg BW-1.min（-1）的速率输注60 min。通过同一导管连续输注葡萄糖溶液以维持血糖处于稳态。使用对侧导管采集用于测量的血样。血浆总胆固醇、胆固醇酯、游离胆固醇和磷脂浓度RPM 0和RPM 20组均高于Con组，而RPM 60组低于RPM 0组（P < 0.05）。血浆Met浓度在RPM 60组最高（P < 0.05）。在EGC实验中，RPM 60组的葡萄糖输注速率大于RPM 0和RPM 20组，且达到50%最大葡萄糖输注速率的有效胰岛素浓度低于RPM 0组（P < 0.05），提示RPM 60组胰岛素敏感性增强。尽管在RPM 0、RPM 20和RPM 60中从EGC数据评估的胰岛素敏感性与Con没有差异，但在RPM 0中观察到轻微下降，并且在RPM 60中的胰岛素敏感性高于Con。我们的EGC实验结果表明，饲喂RPM导致胰岛素敏感性增加，这表明饮食Met通过胰岛素作用影响饲喂含LCFA-Ca饮食的泌乳奶牛的脂质代谢。
The hyperinsulinemic-euglycemic clamp (EGC) technique was used to investigate the effects of calcium salts of long-chain fatty acids (LCFA-Ca) and rumen-protected Met (RPM) on insulin sensitivity in the peripheral tissues of lactating cows. Six multiparous Holstein cows were used in a 3 x 3 Latin square experiment in each 14-d period. Dietary treatments were 0 (RPM0), 20 (RPM20), and 60 (RPM60) g/d of RPM, supplemented with a diet containing 1.5% of LCFA-Ca equal to 110% of the cows' ME requirement. And as a control for the 3 LCFA-Ca-containing diets, a dietary treatment without LCFA-Ca (Con) was also included. After a 10-d adaptation period, milk samples were collected for 4 d, and EGC experiments were performed on d 14 of each treatment period. Insulin solution was infused through a jugular vein catheter at a rate of 0.1, 0.2, 0.3, and 0.4 milliunits.kg BW-1.min(-1) for 30 min and then at a rate of 0.5 milliunits.kg BW-1.min(-1) for 60 min. Glucose solution was variably infused to maintain plasma glucose at steady state through the same catheter. Blood samples for measurements were taken using the contralateral catheter. Plasma total cholesterol, cholesterol ester, free cholesterol, and phospholipid concentrations in RPM0 and RPM20 were higher than those in Con, whereas the concentrations in RPM60 were low at the same degree of those in RPM0 (P < 0.05). Plasma Met concentration was greatest in RPM60 (P < 0.05). In the EGC experiment, the glucose infusion rate was greater in RPM60 than in RPM0 and RPM20 and an effective concentration of insulin resulting in 50% maximal glucose infusion rate was lower in RPM60 compared with RPM0 (P < 0.05), indicating that insulin sensitivity was intensified in RPM60. Although the insulin sensitivity evaluated from the EGC data in RPM0, RPM20, and RPM60 was not different from Con, a slight decline was observed in RPM0 and insulin sensitivity in RPM60 was higher than Con. Our results from the EGC experiment demonstrated that the feeding RPM lead to increased insulin sensitivity, which suggests that dietary Met affects lipid metabolism via insulin action in lactating dairy cows fed a LCFA-Ca-containing diet.