Palatability of shrubs and fodder trees measured on sheep and camels. Methodological approach and preliminary results
1994
Ben Salem, H. | Nefzaoui, A. | Abdouli, H. (Institut National de la Recherche Agronomique de Tunisie, Ariana (Tunisia). Laboratoire de Nutrition Animale)
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 (C1 to C5) containing each four species. Each combination was tested over a 15-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 (l1), average food intakes on the first five-day period (l5), the second five-day period (l10) and the third five-day period (l15) were compared. Significant correlations (P less than 0.05) were found between l1 and l5 (r=0.93), l5 and l10 (r=0.75) or l15 (r=0.61) and l10 and l15 (r=0.87) for sheep. These correlations were higher for camels and intakes may be predicted by the following regression equations: l5 = 1.09l1+0.07 (r=0.96), l10 = 1.15l1 + 0.25 (r=0.85), l15 = 1.41l1 + 0.33 (r=0.78). As the range species were not distributed in the same amounts, intakes were expressed as a percent of the relative distributed quantities (l1/D1, l5/D5, l10/D10 and l15/D15). The same trend reported above was observed between l1/D1 and l5/D5 or l10/D10 or l15/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, l1/D1 and l5/D5 ratios were reported to hay intake (Hl)/hay distributed (HD) ratio. Two indexes were then calculated: R1=(l1/D1)/(Hl1/HD1) and R2=(l5/D5)/(Hl5/HD5). R1 and R2 were found to be highly correlated for sheep (r=0.94) and camels (r=0.92). Therefore, R1 was chosen as a palatability index. The range species were ranked using this index and animals preferences were established.
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