Expression analysis of rumen epithelium of cattle during weaning

Investigation of whole genome gene expression level changes in rumen epithelium of dairy cattle at different stages of rumen development and on different diets. Overall design: An 18-chip study using total RNA recovered from three calves per developmental stage or diet including 3 wks of age fed milk replacer (milk) only, 6 wks of age fed milk, 8 wks of age (2 wks post weaning) fed milk + calf starter (grain), 8 wks of age (2 wks post weaning) fed milk + orchard grass hay (hay), 10 wks of age (4 wks post weaning) fed milk + grain, or 10 wks of age (4 wks post weaning) fed milk + hay. Each chip measures the expression level of approximately 41,000 transcripts from cattle.