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）是一种具备应用潜力的技术，可对机体同化而非仅摄入的营养物质进行时间整合性定量估算。这一特性使其能够被用于评估膳食核苷酸与谷氨酸对断奶仔猪大脑碳周转（δ13C）的影响。本试验选用87头21日龄断奶仔猪，其中3头于试验第0天（更换日粮前）屠宰，剩余84头采用随机完全区组设计，按2×2因子试验设置处理组（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。采集的样本通过同位素比值质谱法进行分析，并采用SAS软件NLIN过程开展非线性回归分析，将数据拟合至一级动力学方程以生成指数变化曲线。结果显示，相较于其他日粮组，添加谷氨酸的日粮组脑组织碳周转时间（t95%）显著更短（P<0.05）；该结果支持谷氨酸可促进仔猪大脑发育这一结论，原因在于尽管断奶仔猪在断奶后存在能量不足的情况，但添加谷氨酸的日粮组中该脑组织的13C原子整合速率最快。