EFFECT OF DRYING METHOD ON CHEMICAL-COMPOSITION AND IN-VITRO DIGESTIBILITY OF MULTIPURPOSE TREE AND SHRUB FODDERS

Methods of drying fodder (sun-air- vs oven-drying) from 8 multi-purpos e trees and shrubs were compared with freeze-drying in one experiment. Twelve-month-old coppice foliage (leaf and petioles) was separated fr om browseable stem components. The samples were either sun-air-dried f or 3 days at 25 degrees C maximum day temperature or oven-dried at 65 degrees C for 48 hours. These dried samples were compared with freshly cut samples that were freeze-dried in liquid nitrogen. In a second ex periment, both leaf and browseable stem components of the fodder were either sun-air- or oven-dried as in Experiment 1 above. Dry matter, ac id and neutral detergent fibre (ADF; NDF), lignin, soluble polyphenoli cs, NDF insoluble condensed tannins, total N and NDF-N concentrations were determined. The in vitro digestibilities of both organic and dry matter (IVOMD, IVDMD) were also determined. Major differences were rec orded in fibre and nutrient concentrations between multi-purpose tree species, fodder components and drying methods. Flemingia macrophylla a nd Acacia angustissima had the lowest overall IVDMD, probably on accou nt of their high ADF, NDF and lignin concentrations. Oven-drying resul ted in an overall increase in ADE NDF and lignin concentrations compar ed with sun-drying and freeze-drying. However, oven-drying resulted in an overall reduction in soluble polyphenolics, total N, NDF-N and IVO MD. The implications of the effects of drying method on in vitro diges tibility values are discussed in the context of preservation of the fo dders for dry season use.