Garssen G J, Geesink G H, Hoving-Bolink A H, Verplanke J C
DLO-Institute for Animal Science and Health (ID-DLO), Research Branxh Zeist, P.O. Box 501, 3700 Am Zeist, The Netherlands.
Meat Sci. 1995;40(3):337-50. doi: 10.1016/0309-1740(94)00034-5.
Sixty male calves were assigned to one of four treatments, including (1) an untreated control, (2) clenbuterol; 1·6 mg/(calf.day), (3) and (4) salbutamol: 60 and 100 mg/(calf.day). Animals were milk-fed during 24 weeks, and β(2)-agonists (BA) treatment occurred during the last 4 weeks including a 3-day withdrawal period before slaughter. Under identical feed intake amongst groups, treatments with BA had significantly positive effects on carcass weights and dressing percentages. BA induced muscle hypertrophy as evidenced by an improved EUROP carcass classification, 1 19-24% higher m. longissimus loin eye area and higher muscle protein/DNA and protein/RNA ratios. Through a dilution effect, this might explain the lower haem content of the m. semimembranosus and m. longissimus lumborum (LL) and diminished Hunter a(∗) value (redness) of the latter muscle. A higher ultimate pH was found in the m. semitendinosus and m. psoas major of BA-treated calves. The m. longissimus thoracis glycogen content appeared to be lowered by salbutamol. No effects of BA were encountered for water-holding properties of this muscle. Significantly higher shear force values (31-45%) for treated animals were measured for the LL which were parallelled by higher initial values for the calpain-inhibiting activity of calpastatin and a decrease of the μ-calpain/calpastatin ratio. EUROP fatness of carcasses and LL intramuscular fat content tended to be lowered by both BA. Effects of clenbuterol and of the higher salbutamol dose, which on a molecular base was administered at a 70 times higher level, were roughly of a comparable order. The lower dose mostly had intermediate effects. This means that in veal calves, clenbuterol is biologically more potent than salbutamol.
60头雄性犊牛被分配到四种处理方式之一，包括：（1）未处理的对照组；（2）克伦特罗，1.6毫克/（犊牛·天）；（3）和（4）沙丁胺醇，60毫克/（犊牛·天）和100毫克/（犊牛·天）。动物在24周内进行人工哺乳，β(2)-激动剂（BA）处理在最后4周进行，包括屠宰前3天的停药期。在各组采食量相同的情况下，BA处理对胴体重和屠宰率有显著的正向影响。BA诱导肌肉肥大，这可通过以下方面得到证明：EUROP胴体分级得到改善，背最长肌腰眼面积高19 - 24%，肌肉蛋白/DNA和蛋白/RNA比率更高。通过稀释效应，这可能解释了半膜肌和腰最长肌（LL）血红素含量较低以及后者肌肉Hunter a(∗)值（红色度）降低的原因。在BA处理的犊牛的半腱肌和腰大肌中发现了较高的最终pH值。沙丁胺醇似乎降低了胸最长肌的糖原含量。BA对该肌肉的持水性能没有影响。对于LL，处理组动物的剪切力值显著更高（31 - 45%），同时钙蛋白酶抑制蛋白的钙蛋白酶抑制活性初始值更高，且μ-钙蛋白酶/钙蛋白酶抑制蛋白比率降低。两种BA都倾向于降低胴体的EUROP脂肪度和LL肌内脂肪含量。克伦特罗和更高剂量沙丁胺醇的效果在分子水平上，后者的给药剂量高70倍，大致处于相当的水平。较低剂量大多产生中间效应。这意味着在犊牛中，克伦特罗在生物学上比沙丁胺醇更有效。
