Facilitative UT-B urea transporters play an important role in the urea nitrogen salvaging process that occurs in the gastrointestinal tract of mammals, particularly ruminants. Gastrointestinal UT-B transporters have previously been reported in various ruminant species-including cow, sheep and goat. In this present study, UT-B transporter localization was investigated in tissues throughout the bovine gastrointestinal tract. RT-PCR analysis showed that UT-B2 was the predominant UT-B mRNA transcript expressed in dorsal, ventral and cranial ruminal sacs, while alternative UT-B transcripts were present in other gastrointestinal tissues. Immunoblotting analysis detected a strong, glycosylated ~50 kDa UT-B2 protein in all three ruminal sacs. Immunolocalization studies showed that UT-B2 protein was predominantly localized to the plasma membrane of cells in the stratum basale layer of all ruminal sac papillae. In contrast, other UT-B protein staining was detected in the basolateral membranes of the surface epithelial cells lining the abomasum, colon and rectum. Overall, these findings confirm that UT-B2 cellular localization is similar in all ruminal sacs and that other UT-B proteins are located in epithelial cells lining various tissues in the bovine gastrointestinal tract.

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Most measurements of digestibility are earned out with sheep rather than cattle because of the smaller amounts of feed and faeces involved. Yet the results are most often used with cattle. It is widely believed that digestibility in sheep is poorer than cattle with low digestibility feedstuffs and better with high digestibility feedstuffs, but that the magnitude of the differences is small. However, this belief is largely based on work with forages and there have been few direct comparisons between cattle and sheep fed concentrate ingredients. The objective of this experiment was to compare the digestibility by cattle and sheep of five samples of concentrate ingredients: citrus pulp, molassed beet pulp, corn gluten feed, barley and grain screenings.

Most measurements of digestibility are earned out with sheep rather than cattle because of the smaller amounts of feed and faeces involved. Yet the results are most often used with cattle. It is widely believed that digestibility in sheep is poorer than cattle with low digestibility feedstuffs and better with high digestibility feedstuffs, but that the magnitude of the differences is small. However, this belief is largely based on work with forages and there have been few direct comparisons between cattle and sheep fed concentrate ingredients. The objective of this experiment was to compare the digestibility by cattle and sheep of five samples of concentrate ingredients: citrus pulp, molassed beet pulp, corn gluten feed, barley and grain screenings.