UTILIZATION OF BROWSE SUPPLEMENTS WITH VARYING TANNIN LEVELS BY ETHIOPIAN MENZ SHEEP - 1 - INTAKE, DIGESTIBILITY AND LIVE WEIGHT CHANGES

The effect of tannins in browse supplements on intake, digestibility a nd live weight changes was evaluated using sixty-six male Ethiopian Me nz sheep in a 90-day trial. Teff straw (Eragrostis tef) was fed ad lib itum (control diet), or supplemented with 190 g dried leaves of six Se sbania sesban accessions with increasing levels of condensed tannin (S 1, S2, S3, S4, S5 and S6), lablab (Dolichos lablab), tagasaste (Chamae cytisus palmensis), leucaena (Leucaena leucocephala) and goetzei (Sesb ania goetzei), in a completely randomized block design. The condensed tannins were highest in goetzei, S6, S5 and leucaena, intermediate in S4, S3, S2 and S1, and lowest in tagasaste and lablab. The forages dif fered significantly (P < 0.05) in their rates of degradation and truly undegradable dry matter. Lablab had lower water solubility and higher (P < 0.05) truly undegradable dry matter than the other browse supple ments. With increasing tannin levels among Sesbania accessions, there was a significant decrease (P < 0.05) in the rate of degradation. Anim als supplemented with forage legumes with low condensed tannin levels such as lablab, S1, S2, and S3 had a lower teff straw intake than thos e on the control diet. The converse was true for those fed with the hi gh tannin supplements such as S4, S5, S6 and goetzei. Supplementation significantly (P < 0.05) increased total dry matter intake and live we ight gains (LWG). The animals on the control diet lost weight (-1.9 g/ kgW(0.75)), while the supplemented animals gained between 2.9 and 4.4 g/kgW(0.75) daily. Leucaena supplementation promoted higher (P < 0.05) LWG than lablab, S1 and goetzei. With increasing tannin levels among Sesbania accessions, there was an increase (S1 < S2 < S3 < S4) followe d by a decrease (S6 > S5 > goetzei) in LWG. The digestibilities of tot al DM and the supplements did not differ significantly (P > 0.05) betw een the diets, although the neutral detergent fibre (NDF) digestibilit y decreased significantly (P < 0.05) with supplementation. The control diet had significantly higher NDF digestibility than the leucaena, S3 , S4, S5 and S6 supplemented diets. Results have beneficial attributes at low levels in ruminants. Condensed tannins confer important advant ages in ruminant nutrition with respect to the prevention of excessive degradation of protein in the rumen.