Timing carbon turnover (δ13C) in weaned piglet’s brain by IRMS

Abstract Isotope-ratio mass spectrometry (IRMS) is a potential tool that provides time-integrated estimate of assimilated and not just ingested nutrients. This feature turned possible its application to evaluate the effects of dietary nucleotides and glutamate on carbon turnover (δ13C) in the brain of weanling piglets. Eighty-seven piglets weaned at 21-day-old were used, being three piglets slaughtered at day-0 (prior to diet-switch) and, the remaining 84 randomly assigned in a complete block design with a 2 x 2 factorial arrangement of treatments (two nucleotide levels: 0% and 0.1% and, two glutamate levels: 0% and 1%). On trial days 3, 6, 9, 14, 21, 35 and 49, three piglets per treatment were also slaughtered. The samples were analyzed by IRMS and adjusted to the first-order equation by a nonlinear regression analysis using NLIN procedure of SAS, in order to obtain the exponential graphics. The carbon turnover (t95%) verified for cerebral tissue was faster (P<0.05) for diet containing glutamate in comparison to other diets, supporting the fact that glutamate contributed to develop the piglets’ brain, due to the fastest incorporation of 13C-atoms in this tissue at post-weaning phase, despite the energy deficit experienced by them.

摘要：同位素比值质谱法（Isotope-ratio mass spectrometry, IRMS）是一类极具应用潜力的检测技术，可实现对机体同化（而非仅摄入）营养物质的时间整合性评估。这一特性使其能够用于评估日粮核苷酸与谷氨酸对断奶仔猪脑组织碳周转（δ¹³C）的影响。本研究选取87头21日龄断奶仔猪，其中3头于日粮转换前第0天屠宰；剩余84头采用完全区组设计随机分组，开展2×2因子试验处理：设置2个核苷酸添加水平（0%与0.1%）、2个谷氨酸添加水平（0%与1%）。在试验第3、6、9、14、21、35及49天，每个处理组均屠宰3头仔猪。采集的样本通过IRMS进行检测，并借助SAS软件的NLIN程序执行非线性回归分析，将数据拟合至一级动力学方程以生成指数拟合图谱。结果表明，与其余日粮组相比，添加谷氨酸的日粮组脑组织碳周转95%所需时间（t95%）显著更短（P<0.05）。尽管断奶后仔猪存在能量亏空，但该组脑组织中¹³C原子的同化速率最快，这一结果证实谷氨酸可促进仔猪脑组织发育。