Effect of condensed tannins on the efficiency of forage legume protein use in sheep. (Short Communication)

Abstract

1lA EFFECT OF CONDENSED TANNINS ON THE EFFICIENCY OF FORAGE LEGUME PROTEIN USE IN SHEEP FENG YU*, G.E. EAGLETON* and R.A. LENG** Condensed tannins in some leguminous forages, such as Lotus species, sainfoin and cromnvetch, may protect protein from degradation by ruminal microbes. Barry and Blaney (1987) reported increased weight gains in sheep when Sainfoin shows proportions of tanniferous legumes increased in the diets. more rapid initial growth than alfalfa on the Loess Plateau of China during The the spring and could be a useful component of a legume-based pasture. purpose of the experiment was to compare sainfoin hay and alfalfa hay mixtures with each legume alone as supplements to sheep fed crop residues. In particular the effects of each supplement on efficiency of feed utilisation, weight gain and wool growth were measured. Thirty female Merino lambs were assigned at random to five treatment groups. After 15 days of adjustment, data were collected over 8 weeks. Four sheep fitted with rumen cannulas and fed diet 5 were used to measure the rumen degradability of the DM and protein of the feeds. Mixing tannin-containing sainfoin with alfalfa as a supplement to a 2% urea ensiled wheat straw chaff basal diet fed to sheep generally improved total intake, live-weight gain and wool growth of lambs compared to equivalent amounts of sainfoin or alfalfa (PxO.05). The degradation in the rumen of protein was more rapid with alfalfa than with sainfoin up to 8 hours incubation. The results are presented in the table. Table 1 Total intake, liveweight changs, wool growth and rumen ammonia of lambs fed legume suppliements on straw basal diets The results indicate that a number of tanniferous and non-tanniferous legumes added to a basal diet of straw increased intake, efficiency of feed utilisation for liveweight gain and wool growth. The results suggest that tanniferous plants can provide protection from microbial degradation in the A combination rumen of protein of non-tanniferous legumes when fed together. of two legumes when supplemented to a wheat straw-based diet improved productivity greater than either legume alone. BARRY, T.N. PP. 91-97 & BLANEY, B.J. (1987). In: 'The Nutrition of Herbivores'. Eds J.B. Hacker & J.H. Ternouth. Academic Press, Sydney. The authors wish to acknowledge the IFS for a Grant supported. * Gansu Grassland Ecological Research Institute, Lanzhou, Gansu, 730020, China. ** Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW 235 1, Australia.