PALATABILITY OF SHRUBS AND FODDER TREES MEASURED ON SHEEP AND CAMELS. Methodological approach and preliminary results

Experiments were performed to study the effect of measurement duration on palatability of eleven range species and to define thereafter a palatability index. The range species were randomly distributed in five combinations (C l to C5) containing each four species. Each combination was tested over a15-day experimental period on four one-year old sheep and five two-year old one-humped camels (camelus dromedarius).. Animals received daily at 0800h the four range species ad libitum and were supplemented at 1700h with spineless cactus. The barley hay (standard food) was distributed with the range species only during the first five days of each experimental period. Food intakes measured on the first day (I I ), average food intakes on the first five-day period (E), the second five-day period (Il O) and the third five-day period (II 5) were compared. A significant correlations (PcO.05) were found between II and 15 (r=0.93), 15 and 110 (r=0.75) or 115 (r=0.61) and 110 and 115 (r=0.87) for sheep. These correlations were higher for camels and intakes may be predicted by the following regression equations: 15 = l .0911+0.07 (r=0.96), 110 = 1 .l511 + 0.25 (r=0.85), II 5 = 1.41 II + 0.33 (r=O.78). As the range species were not distributed in the same amounts, intakes were expressed as a percent of the relative distributed quantities (I I /DI, 15/D5, 110/D10 and I15/D15). The same trend reported above was observed between H/DI and 15/D5 or II O/D10 or 115/D15. Such results suggested that one day of measurement may be sufficient for palatability assessment. As far as all the range species were not distributed in one time, Il/DI and 15/D5 ratios were reported to hay intake (Hl)/hay distributed (HD) ratio. Two indexes were then calculated: R1=(II/DI)/(HIIIHDI) and R2=(15/DS)/(H15/HD5). R I and R2 were found to be highly correlated for sheep (r=0.94) and camels (r=0.92). Therefore, R I was chosed as a palatability index. The range species were ranked using this index and animals preferences were established.