Effects of compounds extracted from tagasaste on in sacco digestibility and rate of particulate outflow from the rumen

Abstract

Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 EFFECTS OF COMPOUNDS EXTRACTED FROM TAGASASTE ON IN SACCO DIGESTIBILITY AND RATE OF PARTICULATE OUTFLOW FROM THE RUMEN J.B.J. MERCYA, N.J. EDWARDSA, P.E. VERCOEA, R.P. ANSOTEGUIB and N.D. COSTA * Faculty of Agriculture , The University of Western Australia, Nedlands, W.A. 6907 B Animal and Range Science Department, Montana state University, Bozeman, MT 59717 U.S.A ' School of Veterinary Studies, Murdoch University, Murdoch, W.A. 6150 C Tagasaste (Chamaecytisus prolferus) is a hardy leguminous shrub suited to poor sandy soils in southern Australia. Oldham et al. (1994) have shown it to be a suitable feed for cattle production, however recent studies have shown growth to be extremely seasonal (McNeil1 et al. 1996). Steer growth rates of 1.0-1.5 kg/hd.day during the winter-spring period coincide with a low concentration of low molecular weight phenolic compounds in the edible plant material, whereas poor animal performance during the late summerautumn period coincides with a high level of these compounds (N.J. Edwards, unpublished). The objective of this study was to examine the effects of low molecular weight phenolic compounds extracted from tagasaste on rumen activity in sheep. A crude phenolic solution was extracted from tagasaste leaf using a 50/50 mixture of ethanol and water. Phenolic concentration was determined using the Folin-Dennis assay, with tannic acid as the standard. Three levels of extract were infused, with artificial saliva (McDougall 1948) as the vehicle, for 48 hours directly into the rumen of four fistulated merino wethers in a complete Latin Square design. The animals received a diet of lupins and oaten-chaff and their feed intake (1200 g/hd.day) was kept constant throughout the experiment by adding any feed refusals to the rumen through the fistula every 3 hours. Retention time was estimated by adding a bolus of Ytterbium impregnated oaten-chaff to the rumen at the start of each infusion period and faecal samples were subsequently collected as they became available. The in sacco digestibility of lupins and wheaten-straw were determined by suspending nylon bags containing ground samples of each material in the rumen during each infusion for 12 and 36 hours respectively. In sacco digestibility and log transformed retention time data were analysed by the Duncan New Multiple Range test. Table 1. Mean retention time of particulate matter (2 SE), , and in sacco dry matter (DM) disappearance (2 SE) of lupins and wheaten-stra w, in the rumen of sheep infused intra-ruminally with a crude extract from tagasaste This project was partly funded by the Meat Research Corporation. MCDOUGALL, E.I. (1948). Biochem. J. 43: 99-109. McNEILL, D.M., ALLEN, G.M., EDWARDS, N.J. and OLDHAM, C.M. (1996). Proc. Aust. Sot. Anim. Prod. 21: 411. OLDHAM, C.M., ALLEN, G.M. and FORTUNE, J.A. (1994). Proc. Aust. Sot. Anim. Prod. 20: 85-88. 377