Effects of the beta-adrenergic agonist clenbuterol in cows: lipid metabolism, milk production, pharmacokinetics, and residues.
Effects of the beta-adrenergic agonist clenbuterol in cows: lipid metabolism, milk production, pharmacokinetics, and residues.
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DOI：
10.2527/1993.7171875x
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发表时间：
1993-07
影响因子：
3.3
通讯作者：
B. Stoffel;H. Meyer
中科院分区：
文献类型：
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作者：
B. Stoffel;H. Meyer
研究了β -肾上腺素能激动剂克伦特罗对6头哺乳期瑞士棕色奶牛脂质代谢、产奶量、药代动力学和残留的影响。其中4只用促生长剂量的克仑特罗/千克体重5微克，混合在浓缩物中，每天给药两次，持续3周。剩下的两头奶牛作为对照。所有动物均处于泌乳第三期，根据个体产奶量和体重，分别饲喂玉米青贮、干草和精料的饲粮。牛奶和血液样本按照严格的时间表收集进行分析。在处理过的动物和对照动物中，产奶量和牛奶含量（甘油三酯、蛋白质和乳糖）在数量上是相同的，而在处理过克伦特罗的动物中，乳脂的脂肪酸组成发生了显著的质变。与对照组相比，不饱和脂肪酸的相对含量（占总脂肪酸的百分比），特别是油酸（顺式- δ 9-十八烷酸，18:1）显著增加，同时过渡链长度的脂肪酸（月桂酸[12:0]和肉豆酱酸[14:0]）减少。血浆葡萄糖和游离脂肪酸浓度升高。胰岛素样生长因子I的浓度保持不变。我们得出的结论是，克伦特罗的生理作用仅限于对身体成分的重新分配作用，而克伦特罗对产奶量的影响很小。在治疗开始时，可观察到血浆（3.4 +/- 2.0 ng/mL）和牛奶（10.8 +/- 4.7 ng/mL）中盐酸克仑特罗浓度立即升高。克仑特罗浓度在10 d后达到峰值，并一直保持不变，直到治疗结束。（摘要删节250字）
The effects of the beta-adrenergic agonist clenbuterol on lipid metabolism, milk production, pharmacokinetics, and residues were studied in six lactating Brown Swiss cows. Four of these were treated with the growth-promoting dose of 5 micrograms of clenbuterol/kg of BW, mixed within the concentrate, and administered twice a day for 3 wk. The remaining two cows served as controls. All animals were in their third phase of lactation and were fed diets containing corn silage, hay, and concentrate according to individual milk production level and body weight. Milk and blood samples were collected for analysis following a rigid time schedule. Milk production and milk contents (triglycerides, protein, and lactose) were quantitatively identical in both treated and control animals, whereas significant qualitative changes occurred in the fatty acid composition of milk lipids in clenbuterol-treated animals. Compared with the controls, the relative amount (percentage of total fatty acids) of unsaturated fatty acids, particularly oleic acid (cis-delta 9-octadecaonate, 18:1), increased considerably with a simultaneous decrease of the transition chain length fatty acids (lauric acid [12:0] and myristic acid [14:0]). Plasma glucose and FFA concentrations were elevated. Concentrations of insulin-like growth factor I remained unchanged. We conclude that the physiological effect of clenbuterol is limited to the repartitioning effect in body composition, and that milk production is affected only slightly by clenbuterol. An immediate increase of clenbuterol concentrations in plasma (3.4 +/- 2.0 ng/mL) and milk (10.8 +/- 4.7 ng/mL) could be observed at the commencement of treatment. Clenbuterol concentration peaked after 10 d and remained constant until the end of the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)