MORPHOLOGICAL AND NUTRITIONAL CHARACTERISTICS OF THE CLADODES OF SIXTEEN CULTIVARS AND CLONES OF SPINELESS CACTUS GROWING IN TUNISIA
This study aimed to evaluate morphological characteristics and to determine the nutritive value of 16 cultivars and clones of spineless cactus growing in central Tunisia (13) and in Tunis (3) since 1998. Three plants of each cultivar were used and three cladodes from each plant were harvested in September 2005. The length (L), width (Wd), thickness (T) and weight (Wt) of each cladode were measured. Each cladode was cut into small pieces and 100 g of the chopped material were dried at 100°C for 72 h for dry matter (DM) determination. Another sample was dried at 50°C for a week, then ground (1 mm-screen) and stored until analyzed. Morphological parameters varied greatly among cultivars. They could be allocated into two groups. The first group includes cultivars with heavy cladodes (>0.8 kg/cladode). The weight of the cladodes of the cultivars in the second group ranged between 0.45 and 0.75 kg/cladode. Cladode length varied from 33 to 39 cm and the width from 16 to 23 cm. The cultivar Opuntia undulata had big cladodes (41.4×27.1 cm, L×Wd). However, Opuntia cochinilifera had the smallest cladodes (20.6×8.3 cm, L×Wd). The average number of cladodes in each cactus plant ranged from 14 (Opuntia ficus-indica f. inermis (OFI), Algeria) to 55 (OFI, Sbeitla). The DM content ranged from 6 to 12% (P<0.001). Cladodes of all cultivars were high in ash (20-29% of DM). The crude protein content (CP) was low in the cladodes of 13 cultivars (4-6% of DM) and relatively high in the three others (9-11% of DM). Overall, fiber content was relatively low in all cultivars. The NDF content ranged from 29 to 41% of DM, the ADF from 11 to 15% of DM and the ADL from 1.5 to 4.6% of DM. Cladodes of all cultivars were high in Ca (4-8% of DM) and K (3-8% of DM) but the Ca/P ratio was too high (>50). High levels of oxalates were detected in the cladodes of the 16 cultivars (7 to 17% of DM). The two cultivars OFI-Tunis and OFI clone 1270 were highest in oxalates (14 and 17% of DM, respectively). Gas production (GP) measured in calibrated glass syringes containing rumen fluid and artificial saliva and the substrate (0.2 g) incubated at 39°C for 24 h ranged from 35 and 50 ml/0.2 g of organic matter (P<0.001). Cladodes of OFI Oueslatia exhibited the highest GP (50 ml/0.2 g OM). The GP was intense during the first 24 h of incubation then slightly increased during the following 24 h and stabilized between 48 and 72 h of incubation. The GP rate from the insoluble fraction of the substrate is high for most cultivars (ca. 10% per h). There were negative correlations between ADF and GP (r=-0.48, P<0.001) and oxalate content and GP (r=-0.56, P<0.001). The results indicate a great variation of the morphological parameters and nutritive value between the 16 cultivars and clones of spineless cactus. The high level of CP in OFI clone 1270, Opuntia sp. 1233 and Opuntia cochinilifera did not improve their in vitro digestion.
Yousfi, I., Ben Salem, H. and Laamouri, A. (2013). MORPHOLOGICAL AND NUTRITIONAL CHARACTERISTICS OF THE CLADODES OF SIXTEEN CULTIVARS AND CLONES OF SPINELESS CACTUS GROWING IN TUNISIA. Acta Hortic. 995, 331-336
spineless cactus, cultivars, clones, cladodes, morphological parameters, nutritive value