VOLUNTARY INTAKE AND GASTRIC DIGESTION OF 2 BAYS BY LLAMAS AND SHEEP - INFLUENCE OF CONCENTRATE SUPPLEMENTATION

The efficiency with which llamas and sheep digest various roughages wa s compared in France in 1993. Six llamas (three of which were rumen-ca nnulated) and six rumen-cannulated sheep were simultaneously given thr ee different diets: (i) a grass hay low in N content (HLN), (ii) the s ame hay with barley, representing 25% of the total dry matter (HLN + B ) and (iii) a cocksfoot grass hay, rich in nitrogen (HRN). Daily forag e dry matter intake was slightly, but not significantly, lower in llam as (55.9 g/kg W-0.75 v. 60.3 g/kg W-0.75 in sheep). Intake behaviour w as similar for the two species except that the number of rumination pe riods was lower with llamas (P < 0.05). With all diets, the digestibil ity of both organic matter and cell walls ( estimated from neutral det ergent fibre) was higher in llamas (+ 5.6 and + 6.5 units respectively , P < 0.001). The higher digestibility in llamas may be related to the slightly lower level of intake and to the lower dry matter turnover r ate in the forestomachs compared to sheep (3.9%/h v. 5.3%/h, P < 0.01) . However, in sacco degradation of both hays were higher in llamas' fo restomachs after 24 h of incubation (+ 6.5%, P < 0.01) and 48 h (+ 4.3 %, P < 0.05) than in sheep. The high microbial efficiency of the llama s can be ascribed to the physical and chemical characteristics of thei r forestomach contents, which had a higher liquid turnover rate(+ 1.4% /h, P < 0.05), a lower volatile fatty acid concentration (P < 0.01), a higher and more constant pH (P < 0.01) than in sheep and a greater bu ffering capacity when pH was close to neutral. These results suggest t he greater ability of llamas to control the physicochemical conditions of their forestomach contents to digest cell walls efficiently and to minimize the negative effects of concentrate supplementation.