PSIX-16 Investigating the development of the fecal microbiome in growing diary calves

Abstract

Abstract Development of the gut microbiome in young animals is critical for maximizing productivity in adults through beneficial functional contributions of symbiotic microbial communities to the health and nutrition of their host. To gain further insight into this process, development of the fecal microbiome in 12 dairy calves was investigated. Fecal bacterial composition was determined at four time points (weeks 0, 4, 8 and 12) using the 16S rRNA gene through PCR-amplification of the V1-V3 regions from fecal microbial genomic DNA, followed by Illumina MiSeq 2X300 sequencing. A comparative analysis of the most highly represented Operational Taxonomic Units (OTU) using the non-parametric Kruskal-Wallis sum-rank test and Wilcoxon pairwise test identified both known and uncharacterized fecal bacterial species whose abundance fluctuated during development of the calves. Four highly represented OTUs were found to have a peak of abundance at week 0, which was followed by significantly lower abundance at later time points (P < 0.05). Notably, OTU JA_ 89-27339, peaked at week 0 (39.3% ± 3.6%), then declined at later time points with respective means of 2.3%, 0.1% and 0.05%. Seven other OTUs were found to peak at an intermediate time point (P < 0.05), including OTU JA_46-21334 which was found in highest abundance at week 4 (4.5% ± 1.2%) compared to means with a range of 0.001% to 0.01% for the other time points. In contrast, another set of well represented OTUs were found to increase in abundance with time, which included OTU JA_84-17601 whose abundance was highest at week 12 (1.4% ± 0.3%) (P < 0.05). These results are indicative of microbial succession in the gastrointestinal tract of dairy calves and highlight candidate bacterial species whose function could be manipulated towards improving the health and productivity of growing dairy calves.