NUTRITIVE VALUE OF FRESH, DRIED (HAY) AND ENSILED VINES OF FOUR SWEET POTATO (Ipomoea batatas) VARIETIES GROWN IN SOUTHERN ETHIOPIA

Abstract

Chemical composition and in vitro true dry matter digestibility (IVTDMD) of fresh, dried (hay) and ensiled vines of two early maturing (Belela and Temesgen) and two medium maturing varieties (Beletech and Tulla) were investigated. Hay was made by sun drying for 3 days. Silages were S1: vine alone, S2: vine+2%molasses, S3: vine+4% molasses, S4: vine+10% sweet potato root (SPR, % of wilted vine weight), S5: vine+20%SPR and S6: vine+30%SPR. They were ensiled in plastic buckets (8 liter) with airtight press cape in triplicate for 90 days in a lab at room temperature of 220C. Data were analyzed using SPSS version 20. Hay of Belela, Temesgen, Beletech and Tulla had 17.5, 13.9 and 15.2 %CP (%DM); 36.3, 35.6, 40.5 and 38.8% NDF (%DM) and 81.1, 82.2, 75.0 and 76.7% IVTDMD, respectively, were found. There was a  decrease in pH of silages (p<0.05), with increasing levels of both molasses and SPR, respectively (3.91-3.66 and 3.91-3.64 in Belela; 3.92-3.72 and 3.92-3.68 in Temesgen; 3.99-3.81 and 3.99-3.75 in Beletech; 4.02-3.92 and 4.02-3.74 in Tulla); CP (19.8-15.8 and 9.8-13.9 in Belela;  20.0-14.2 and 20.0-12.3 in Temesgen; 17.2-11.2 and 17.2-10.9 in Beletech; 17.9-14.3 and17.9-11.6 inTulla); NDF (29.9-27.7 and 29.9-22.9 in Belela; 26.4-25.0 and  26.4.0-20.8 in Temesgen;36.1-29.3 and 36.1-25.4 in Beletech; 34.5-29.0 and 34.5-24.4 in Tulla); ADF (26.7-18.2 and 26.7-15.5 in Belela; 25.5-17.1 and 25.5-14.7 in Temesgen;30.0-20.2 and 30.0-16.0 in Beletech;29.3-19.1 and 29.3-16.2 in Tulla); and ADL (7.1-4.6 and 7.1-3.5 in Belela; 6.9-4.1 and 6.9-2.7 in Temesgen;9.1- 5.1 and 9.1-4.9 in Beletech; 7.9-5.0 and 7.9-4.1 in Tulla) but increased IVTDMD ( 82.5-85.7 and 82.5-87.4, in Belela; 82.1-86.1 and 82.1-88.2 in Temesgen; 79.1-84.1 and 79.1-86.1 in Beletech; 78.9-84.0 and 78.9-85.6 in Tulla). Silages at all additive levels had acceptable pH and good IVTDMD, but 4% molasses, 20 and 30% SPR gave higher IVTDMD. Hay had lower nutrient content and IVTDMD than fresh vine and silages. In conclusion, Belela and Temesgen had better nutritive value than Beletech and Tulla; silage making was better than hay making. Animal evaluation is recommended for further confirmation of the results.Key words: Chemical composition; In vitro true dry matter digestibility; Sweet potato varieties Key words: Chemical composition; In vitro true dry matter digestibility; Sweet potato varieties