新生犊牛营养代谢和激素调节的特点及其在围产期内的发育变化

THE CHARACTERISTICS AND DEVELOPMENTAL CHANGES OF NUTRIENT METABOLISM AND ITS HORMONE CONTROL DURING PERINATAL PERIOD IN NEWBORN CALVES

选用5头黑白花新生公犊,生后12小时内装置固定式颈静脉血管导管,从出生至2周龄每天采血样测定血浆中几种主要代谢成分和代谢激素的含量,以研究围产期内营养代谢和激素调节的生理特点及其发育变化。结果表明:新生公犊血浆葡萄糖(G)、游离脂肪酸(FFA)、a-氨基氮(a-NH_2·N)、乳酸(LA)的含量生后第1天均处于较高水平,2～3天内明显降低,5日龄后趋于稳定。尿素氮(UN)生后1～4天逐渐升高,5日龄后逐渐降低,10日龄后相对稳定。血浆甲状腺素(T_4)、三碘甲腺原氨酸(T_3)、皮质醇(Cort)的浓度生后变动较大,5日龄内呈下降趋势,约1周龄后相对稳定。胰岛素(Ins)水平在出生喂初乳后无明显的年龄性变化特点,改变食物成分可能对其有显著影响。

Five spontaneously delivered Holstein calves with 40、50kg birth weight were chosen and catheterized into jugular vein within 12h after birth as well as used to study the characteristics and developmental changes of nutrient metabolism and its hormone control during the first two weeks of their live. The results showed that the resting concentrations of plasma glucose (G)、 FFA、 a-NH2·N、 lactic acid (LA) and Urea nitrogen (U. N) before initial colostrum feeding on the 1st day were 119.60±34.03mg/dl, 999.25 + 862.28μeq/L, 11.86±1.39mg/dl, 4.24 ±0.24nM/L and 11.94±3.44mg/dl respectively. G、 FFA、 α-NH2·N; LA dropped flu-ctuently to a steady level of 76.21±20.57mg/dl, 402.82±190.74μeq/L, 7.49±2.74mg/ dl and 3.50±0.69mM/dl on the 5th day. U. N increased gradually within the first 4 days and then decreased to a steady level of 8、10 mg/dl on day 10. The mean concentrations of Insulin, Cortisol, T4 and Ts before feeding on the 1st day were 7.33±3.21μu/ml, 12.22±8.21μg/dl, 180.95±77.84ng/ml and 5.41± 0.88ng/ml, respectively. Cortisol, T4 and T3 fell fluctuently to a steady value of 9.37 ±4.18μu/ml, 42.84±22.77ng/ml and l.ll±0.77ng/ml on the 7th day. No significant changes of Insulin was found except day 2, day 9 and day 10, which probably indicate the significant effect of feeding and changing diet from colostrum to milk on Insulin secretion.