Hornick J L, Van Eenaeme C, Diez M, Minet V, Istasse L
Department of Nutrition, Veterinary Faculty, Liège, Belgium.
J Anim Sci. 1998 Jan;76(1):260-71. doi: 10.2527/1998.761260x.
Plasma metabolites and hormones were studied in 16 double-muscled Belgian Blue bulls maintained at low growth (.5 kg/d) for 114 (G2), 243 (G3), or 419 (G4) d (low growth period, LGP) before fattening (rapid growth period, RGP). Animals from the control group (CG) were fed a diet high in energy and protein. The animals from G2, G3, and G4 were fed a restricted amount of a diet low in energy and protein during LGP and the same diet as CG during RGP. Plasma glucose, alpha-amino nitrogen (AAN), NEFA, urea, creatinine, thyroxine (T4), 3,3',5'-triiodothyronine (T3), and IGF-I were measured in blood samples taken fortnightly. Plasma GH and insulin (I) profiles were measured in serial blood samples obtained at three times during growth. The RGP was characterized by an initial compensatory growth, by higher plasma glucose, AAN, and urea levels, and by lower plasma NEFA and creatinine levels. Plasma GH concentration decreased after refeeding. Plasma T4 increased linearly during refeeding, as opposed to T3, which showed a different profile in each group. Plasma IGF-I showed a curvilinear increase during RGP and reached a plateau after 3 mo in each compensating group. In G4, changes of plasma metabolites and hormones differed often distinctly from G2 or G3. During refeeding, higher nutrient supply improved the functionality of the somatotropic axis and increased the concentration of anabolic hormones, allowing rapid muscle deposition. However, animals underfed the longest period behaved differently from the other groups, possibly because they reached a more complete sexual maturity.
在16头双肌比利时蓝牛育肥（快速生长期，RGP）前，对其进行了114天（G2组）、243天（G3组）或419天（G4组）的低生长速度（0.5千克/天）饲养（低生长阶段，LGP），并对其血浆代谢物和激素进行了研究。对照组（CG）的动物饲喂高能量和高蛋白日粮。G2、G3和G4组的动物在LGP期间饲喂限量的低能量和低蛋白日粮，在RGP期间饲喂与CG组相同的日粮。每两周采集一次血样，测定血浆葡萄糖、α-氨基氮（AAN）、非酯化脂肪酸（NEFA）、尿素、肌酐、甲状腺素（T4）、3,3',5'-三碘甲状腺原氨酸（T3）和胰岛素样生长因子-I（IGF-I）。在生长过程中的三个时间点采集系列血样，测定血浆生长激素（GH）和胰岛素（I）水平。RGP的特点是最初的代偿性生长、较高的血浆葡萄糖、AAN和尿素水平，以及较低的血浆NEFA和肌酐水平。重新饲喂后血浆GH浓度下降。重新饲喂期间血浆T4呈线性增加，而T3在每组中表现出不同的变化趋势。血浆IGF-I在RGP期间呈曲线上升，每个代偿组在3个月后达到平台期。在G4组中，血浆代谢物和激素的变化往往与G2或G3组明显不同。重新饲喂期间，较高的营养供应改善了生长激素轴的功能，增加了合成代谢激素的浓度，从而促进了肌肉的快速沉积。然而，长期饲喂不足的动物与其他组表现不同，可能是因为它们达到了更完全的性成熟。
