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Assessment of the colon transcriptome changes from pre- to post-weaning in calves fed elevated levels of milk.

J. K. van Niekerk

Abstract:

M26
Assessment of the colon transcriptome changes from pre- to post-weaning in calves fed elevated levels of milk.
J. K. van Niekerk*1, M. Middeldorp2, L. L. Guan1, M. A. Steele1,3. 1Department of Agricultural, Food and Nutritional Science, University of Alberta Edmonton, AB, Canada, 2Animal Nutrition Group, Wageningen University & Research Wageningen, the Netherlands, 3Department of Animal Biosciences, Animal Science and Nutrition, University of Guelph Guelph, ON, Canada.

In addition to rumen fermentation, colon fermentation plays an important role in providing energy to ruminants as well. The aim of this study was to assess colon epithelial gene expression changes in calves from pre- to post-weaning and to determine if these changes are associated with calf starter (CS) intake, colon mucosa thickness, fecal starch and serum inflammatory marker concentrations in calves fed at a high milk replacer (MR) feeding rate. Six Holstein calves were fed MR (150 g/L) at 15% of BW and volumes were adjusted weekly according to BW. Calves were weaned by reducing milk allocation by 50% during wk 6. Serum was collected for acute phase protein analysis and fecal matter for starch analysis weekly from wk 4 to 12. Endoscopic biopsies of the colon were performed for histological measurements (wk 5, 6, 7, 8 and 12) and transcriptomic analysis (wk 5, 7 and 12). Phenotypic trait data were analyzed using GLIMMIX procedure of SAS with wk as a fixed effect and calf as a random effect. Fecal starch was higher (P = 0.0002) at wk 9 compared with wk 4, 5 and 6 and colon mucosa thickness tended to be decreased (P = 0.08) at wk 8 compared with wk 5. The transcriptome analyses uncovered 10 genes (3 up- and 7 downregulated) differentially expressed (DE) during short-term adaptation (wk 5 to 7) while 65 genes (38 up- and 37 downregulated) were DE during long-term adaptation (wk 5 to 12). Weighted gene co-expression network analysis identified a gene module (517 genes) that had a negative correlation (Pearson correlation) with fecal starch (P = 0.01) and CS intake (P < 0.001) and a positive correlation with colon mucosa thickness (P = 0.02). There were 13 DE genes that overlapped with the significant co-expressed gene module and most of these genes (AQP8, SLC7A8, SLC13A2, SLC9A3, SLC6A14, SLC40A1 and S100A12) were involved in nutrient transport and inflammatory response. This is the first study to provide evidence of these genes being expressed in the colon of young ruminants and their change in expression suggests that they may be used as future gene markers to evaluate nutrient absorption and gut and immune function.

Keywords: colon, transcriptome, mucosa thickness.

Biography: I started my PhD degree in calf nutrition in 2016. I am particularly interested in how nutrition and weaning influence rumen and lower gut (colon) development as well as gut health. I am also interested in developing new techniques that can be used to collect data within the same animal over time to see variation between animals.