Choi B R, Palmquist D L
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691-4096, USA.
J Nutr. 1996 Nov;126(11):2913-9. doi: 10.1093/jn/126.11.2913.
High fat diets often decrease feed intake in dairy cows; however, mechanisms underlying fat-induced depression of feed intake are yet to be established. The postulate that high fat diets decrease feed intake by increasing concentrations of lipid metabolites or satiety hormones in blood was tested by using eight multiparous Holstein cows in a simultaneously replicated 4 x 4 Latin-square design. Treatments were control diet with 1) no fat added, 2) 30 g/kg calcium salts of long-chain fatty acids, 3) 60 g/kg calcium salts of long-chain fatty acids, and 4) 90 g/kg calcium salts of long-chain fatty acids. Cows were fed once daily a diet of concentrate, corn silage, alfalfa haylage and alfalfa hay (50:25:14:11 on a dry matter basis). Dry matter and energy intakes were decreased by inclusion of calcium salts of long-chain fatty acids >30 g/kg of total diet dry matter (P = 0.0001). Plasma nonesterified fatty acids and triglyceride concentrations were increased linearly by feeding increasing amounts of fat (P < 0.003 and P = 0.0001, respectively), whereas plasma beta-hydroxybutyrate and glucose concentrations were not influenced by supplemental fat. Fat supplementation increased postfeeding plasma cholecystokinin concentrations and linearly increased plasma pancreatic polypeptide concentrations. Highest concentrations of plasma cholecystokinin (P < 0.001) and pancreatic polypeptide (P < 0.05) were observed in cows fed the 90 g/kg fat supplement. Plasma insulin was lowered linearly by feeding fat (P = 0.0001). Increased concentrations of cholecystokinin and pancreatic polypeptide were associated with decreased intakes of feed and energy, whereas insulin may not be involved in the control of feed intake in cows fed fat.
高脂日粮通常会降低奶牛的采食量；然而，脂肪诱导采食量下降的潜在机制尚未明确。本研究采用8头经产荷斯坦奶牛，通过同步重复的4×4拉丁方设计，对高脂日粮通过提高血液中脂质代谢产物或饱腹感激素浓度来降低采食量这一假设进行了验证。处理方式包括对照日粮，分别为：1）不添加脂肪；2）添加30 g/kg长链脂肪酸钙盐；3）添加60 g/kg长链脂肪酸钙盐；4）添加90 g/kg长链脂肪酸钙盐。奶牛每天饲喂一次由精料、玉米青贮、苜蓿干草和苜蓿青贮组成的日粮（干物质基础比例为50:25:14:11）。当长链脂肪酸钙盐添加量>30 g/kg日粮干物质时，干物质采食量和能量摄入量降低（P = 0.0001）。随着脂肪饲喂量增加，血浆非酯化脂肪酸和甘油三酯浓度呈线性增加（分别为P < 0.003和P = 0.0001），而血浆β-羟丁酸和葡萄糖浓度不受补充脂肪的影响。补充脂肪增加了采食后血浆胆囊收缩素浓度，并使血浆胰多肽浓度呈线性增加。在饲喂90 g/kg脂肪补充剂的奶牛中，观察到血浆胆囊收缩素浓度最高（P < 0.001），胰多肽浓度最高（P < 0.05）。饲喂脂肪使血浆胰岛素呈线性降低（P = 0.0001）。胆囊收缩素和胰多肽浓度升高与采食量和能量摄入量降低有关，而胰岛素可能不参与脂肪饲喂奶牛的采食量调控。
