B.H. DZOWELA¹, L. HOVE² and P.L. MAFONGOYA²

¹SADC-ICRAF Agroforestry Project, Harare, Zimbabwe
²Department of Research & Specialist Services, Harare, Zimbabwe

Abstract

Methods of drying fodder (sun-air- vs ovendrying) from 8 multi-purpose trees and shrubs were compared with freeze-drying in one experiment. Twelve-month-old coppice foliage (leaf and petioles) was separated from browseable stem components. The samples were either sunair-dried for 3 days at 25°C maximum day temperature or oven-dried at 65°C for 48 hours. These dried samples were compared with freshly cut samples that were freeze-dried in liquid nitrogen. In a second experiment, both leaf and browseable stem components of the fodder were either sun-air- or oven-dried as in Experiment 1 above. Dry matter, acid and neutral detergent fibre (ADF; NDF), lignin, soluble polyphenolics, 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 recorded in fibre and nutrient concentrations between multi-purpose tree species, fodder components and drying methods. Flemingia macrophylla and Acacia angustissima had the lowest overall lVDMD, probably on account of their high ADF, NDF and lignin concentrations.
Oven-drying resulted in an overall increase in ADF, NDF and lignin concentrations compared with sun-drying and freeze-drying. However, oven-drying resulted in an overall reduction in soluble polyphenolics, total N, NDF-N and IVOMD.
The implications of the effects of drying method on in vitro digestibility values are discussed in the context of preservation of the fodders for dry season use.