PALATABILITY OF MULTIPURPOSE TREE SPECIES - EFFECT OF SPECIES AND LENGTH OF STUDY ON INTAKE AND RELATIVE PALATABILITY BY SHEEP

The potential forage value and appropriate length of study on intake a nd relative palatability ranking of 40 multipurpose tree species (MPTs ) were determined using 24 sheep blocked on live weight and age. As th e MPTs had different dry matter contents, intakes were also expressed as a ratio of quantity offered (A(i)/D-i). Using daily Eragrostis tef straw offer (TD) and intake (T), relative palatability indices were ca lculated as R(i) = (A(i)/D-i)/(T-i/TDi). There was a significant (P < 0.0001) decrease in correlation of intake measured in day 1 and subseq uent days (r = 0.88, 0.81 and 0.79 for days 2-4, days 5-8 and days 9-1 2, respectively). A similar trend was observed on corresponding palata bility indices. Individual animal preference and blocking did not affe ct intake and palatability indices significantly (P > 0.05), however s ignificant (P < 0.0001) tree species differences were observed. Result s on linear regression, correlation coefficients, palatability ranking and standard errors of means (adjusted palatability indices) indicate that, if palatability is done to predict long-term intake of MPTs, at least 5 days are appropriate in palatability assessment for sheep. Us ing mean palatability index (days 2-12), the MPTs were grouped into fo ur clusters. The MPTs such as Leucaena leucocephala and Sesbania sesba n which are known to have good nutritive value had high palatability. In the same classification group, there were less known species such a s Acacia venosa, A. persiciflora, A. melanoxylon, A. hockii, A. polyac antha, Tamarindus indica, Chamaecytisus palmensis, Tipuana tipu, Indig ofera arrecta and Atriplex nummularia. Flemingia macrophylla, Erythrin a abyssinica, Acacia salicina, Acacia coriacea, Albizia schimperiana, Ceratonia siliqua, Casuarina glauca and Erythrina burana had poor pala tability. These species seem to have little forage value for animals w ith short-term adaptation periods. Gliricida sepium and Calliandra cal othyrsus although currently being used by farmers had a medium palatab ility ranking.