RESUMO
As short chain fatty acids produced in the forestomach are insufficient to satisfy the energy requirements of the concentrate selecting roe deer (Capreolus capreolus), it is proposed that these animals may have other mechanisms to avoid energy losses due to microbial fermentation. Nutrients bypassing down the ventricular groove (rumen bypass) or ruminal escape of unfermented or partially fermented nutrients may be two alternatives. As metabolic evidence for incomplete fermentation in the forestomach we investigated: (1) the abundance of the sodium-dependent glucose co-transporter (SGLT1) in the duodenum; (2) enzyme activities of maltase, saccharase and alpha-amylase in duodenal and pancreatic tissue; and (3) the proportion of essential, polyunsaturated fatty acids in depot fat samples from ruminants of different feeding type and--for comparison--from animals with a simple stomach. The high abundance of SGLT1, high enzyme activity and the high proportion of polyunsaturated fatty acids in the concentrate selecting ruminants support the hypothesis of rumen bypass or ruminal escape of nutrients in roe deer and reflect differences in nutrient utilization by ruminants that belong to different feeding types.