Harvesting, rumination, digestion, and passage of fruit and leaf diets by a small ruminant, the blue duiker

Because small ruminants (<15 kg) have a high ratio of metabolic rate to fer mentation capacity, they are expected to select and require low-fiber, nutr ient-dense concentrate diets. However, recent studies suggest that small ru minants may not be as limited in their digestive capacity as previously tho ught. In this study, we examined harvesting, rumination, digestion, and pas sage of three diets (domestic figs Ficus carica, fresh alfalfa Medicago sat iva, and Pacific willow leaves Salix lasiandra) ranging from 10 to 50% neut ral detergent fiber content (NDF) in captive blue duikers (Cephalophus mont icola. 4 kg). Harvesting and rumination rates were obtained by observing an d videotaping animals on each diet, and digestibility and intake were deter mined by conducting total collection digestion trials. We estimated mean re tention time of liquid and particulate digesta by administering Co-EDTA and forages labelled with YbNO3 in a pulse dose and monitoring fecal output ov er 4 days. Duikers harvested and ruminated the fig diet faster than the alf alfa and willow diets. Likewise, they achieved higher dry matter, energy, N DF, and protein digestibility when eating figs, yet achieved a higher daily digestible energy intake on the fresh willow and alfalfa than on the figs by eating proportionately more of these forages. Duikers maintained a posit ive nitrogen balance on all diets, including figs, which contained only 6.3 % crude protein. Mean retention time of cell wall in the duikers' digestive tract declined with increasing NDF and cellulose content of the diet. Dige stibility coefficients and mean retention times of these small ruminants we re virtually equivalent to those measured for ruminants two orders of magni tude larger, suggesting that they are well adapted for a mixed diet.