Date-palm leaves, pedicels, date-pits and waste dates are the main date-palm by-products (DPBP), classically used as a complementary feeding source for livestock by oasis farmers. This work aims to assess in vitro the nutritive value of these DPBP, including waste dates from three varieties (Bouarus, Harchaya and Kentichi), and using vetch-oat hay as a reference feed material. Palm leaves showed the highest NDF, ADF, lignin and crude protein contents (609, 435, 84, 64 g kg-1 DM, respectively). After 144 hours of incubation, the highest cumulative gas production was observed for Kentichi dates (330 mL g-1DM) and the lowest for date-pits (69 mL g-1DM). Regardless of the variety, waste dates showed the highest DM effective degradability (ED; assuming a passage rate of 0.03 h-1) and organic matter digestibility (OMD), whereas date-pits seemed to be a poorly degradable material, with an ED coefficient of 0.09 g g-1 DM. The lowest total VFA production from ruminal fermentation was with date-pits and the highest with waste dates of the Bouarus variety. These results suggest that waste dates, albeit their low protein content, should be considered highly digestible with energy concentrations as high as that of vetch-oat hay. Palm leaves and pedicels can be considered as highly fibrous emergency roughages for low-producing animals. Protein supplementation is required when DPBP are included in the diet of ruminants.
Key words: By products - Chemical composition - In vitro fermentation - Nutritive value - Rumen