Fig. 2

a Fatty acid binding protein 2 (FABP2) relative mRNA expression in the gastrointestinal tract section, including rumen, duodenum, jejunum, ileum, large intestine, and cecum as well as fecal samples taken simultaneously from eight Jersey dairy calves at 5 weeks of age. Fresh fecal samples were collected prior to euthanasia, and gastrointestinal samples were collected as tissue specimens, and all samples were flash-frozen immediately in liquid N. RNA extraction, and RT-qPCR analysis was performed according to protocols detailed in Rosa et al. [86]. The mRNA expression data were analyzed using ANOVA with type of tissue (e.g., fecal, rumen, etc.) as the fixed effect and calf as the random effect. b) Relative mRNA expression of keratin 8 (KRT8) in total RNA and mRNA isolated from the same fecal samples (n = 8). Total RNA extraction was performed according to (Rosa et al., [86]), and mRNA was isolated from the same total RNA samples (details in Suppl. Materials). A comparison between total RNA and mRNA was performed using similar protocols as (Rosa and Osorio, [93]), where a single standard curve was constructed with equal amounts of cDNA samples from total RNA and mRNA. The mRNA expression data were analyzed using ANOVA with type of RNA (i.e., total RNA and mRNA) as the fixed effect and calf as the random effect. Data in Panel A and B were log-transformed prior to statistical analysis with the Proc Mixed procedure of SAS 9.4. ^a-eSuperscripts denoting a statistical significance at P ≤ 0.05