Technical Abstract: We have constructed, and are currently characterizing a normalized cDNA library developed from intestinal tissues of Holstein dairy cattle. The library was synthesized from mRNA isolated from duodenal, jejunal and ileal segments of the small intestines of a lactating dairy cow and neonatal calf. After normalization there was a 20-fold reduction of high copy number transcripts and a total of 1.8 x 107 clones with an average transcript length of 1,800 base pairs. This germplasm release defines 5'-sequencing of these clones to date has yielded over 10,000 unique elements (contigs + singletons) with an average length of 628 base pairs that are to be submitted to the Genbank EST database and will be added to the TIGR Bos Taurus gene index. Preliminary analysis has revealed that we are adding significant sequence information to a number of previously identified unique bovine transcripts. Moreover, a large number of ESTs (>750) have been identified that correspond to genes in other animal systems (and are likely physiologically relevant) but have not been previously identified in cattle. Further analysis of these sequences will facilitate the identification and characterization of bovine intestinal genes and critical regulatory proteins important to animal nutrition, growth or health for future investigation. In addition, we are also analyzing over 500 unidentifiable transcripts (not currently represented in nucleotide or protein data bases) that could encode novel genes. Our aim is to use this library resource to develop second-generation research tools (microarrays, genetic tests, etc.) to understand how gene expression patterns and controls are coupled with cellular, tissue and whole animal nutrient-use profiles. We are particularly interested in identifying genes that regulate or are fundamental to metabolic pathways and growth regulatory processes involved in visceral tissue energy and nutrient use. Ultimately this work will facilitate development of new nutritional management and selection strategies essential for optimization of animal production.